Group Title: Molecular Pain 2006, 2:38
Title: Recent advances in basic neurosciences and brain disease: from synapses to behavior
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Title: Recent advances in basic neurosciences and brain disease: from synapses to behavior
Series Title: Molecular Pain 2006, 2:38
Physical Description: Archival
Creator: Bi GQ
Bolshakov V
Bu G
Cahill CM
Chen ZF
Collingridge GL
Cooper RL
Coorssen JR
El-Husseini A
Galhardo V
Gan WB
Gu J
Inoue K
Isaac J
Iwata K
Jia Z
Kaang BK
Kawamata M
Kida S
Klann E
Kohno T
Li M
MacDonald JF
Nader K
Nguyen PV
Oh U
Ren K
Roder JC
Salter MW
et al.
Publication Date: 39081
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Bibliographic ID: UF00100265
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: Open Access:


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Molecular Pain BioMedCent


Recent advances in basic neuroscience and brain disease:

from synapses to behavior
Guo-Qiang Bi1, Vadim Bolshakov2, Guojun Bu3, Catherine M Cahill4, Zhou-Feng Chen5,
Graham L Collingridge6, Robin L Cooper7, Jens R Coorssen8, Alaa El-Husseini9,
Vasco Galhardo10, Wen-Biao Gan11, Jianguo Gu12, Kazuhide Inoue13, John Isaac14,
Koichi Iwata15, Zhengping Jia16, Bong-Kiun Kaang17, Mikito Kawamata18, Satoshi Kida19,
Eric Klann20, Tatsuro Kohno21, Min Li22, Xiao-Jiang Li23, John F MacDonald16, Karim Nader24,
Peter V Nguyen25, Uhtaek Oh26, Ke Ren27, John C Roder28, Michael W Salter16, Weihong Song9,
Shuzo Sugita16, Shao-Jun Tang29, Yuanxiang Tao30, Yu Tian Wang31, Newton Woo32,
Melanie A Woodin33, Zhen Yan34, Megumu Yoshimura35, Ming Xu36, Zao C Xu37, Xia Zhang38,
Mei Zhen28 and Min Zhuo*16

Address: 'Department of Neurobiology, University of Pittsburgh, Pittsburgh, USA, 2Department of Psychiatry, Harvard University, Boston, USA,
3Department of Pediatrics, and Cell Biology and Physiology, Washington University in St. Louis, St. Louis, USA, 4Department of Pharmacology
and Toxicology, Queen's University, Kingston, Canada, 5Department of Anesthesiology, Washington University in St. Louis, St. Louis, USA,
6Centre for Synaptic Plasticity, University of Bristol, Bristol, UK, 7Department of Biology, University of Kentucky, Lexington, USA, SDepartment of
Physiology and Biophysics, University of Calgary, Calgary, Canada, 9Department of Psychiatry, University of British Columbia, Vancouver,
Canada, 1OInstitute for Molecular and Cell Biology, University of Porto, Porto, Portugal, 11Skirball Institute, New York University School of
Medicine, New York, USA, 12Department of Oral and Maxillofacial Surgery, University of Florida, Gainesville, USA, 13Department of
Pharmaceutical Health Care and Sciences, Kyushu University, Kyushu, Japan, 14NINDS, NIH, Bethesda, USA, 15Department of Physiology, Nihon
University, Tokyo, Japan, 16Department of Physiology, University of Toronto, Toronto, Canada, 17Department of Biological Sciences, Seoul
National University, Seoul, Korea, "Department of Anesthesiology, Sapporo Medical University School of Medicine, Sapporo, Japan,
"Department of Agricultural Chemistry, Tokyo University of Agriculture, Tokyo, Japan, 20Department of Molecular Physiology and Biophysics,
Baylor College of Medicine, Houston, USA, 21Division of Anesthesiology, Niigata University, Niigata, Japan, 2Department of Neuroscience and
High Throughput Biology Center, Johns Hopkins University, Baltimore, USA, 23Department of Human Genetics, Emory University, Atlanta, USA,
24Department of Psychology, McGill University, Montreal, Canada, 25Department of Physiology, University of Alberta, Edmonton, Canada,
26Sensory Research Center, Seoul National University, Seoul, Korea, 27Department of Biomedical Sciences, University of Maryland, Baltimore,
USA, 28Department of Medical Genetics and Microbiology, University of Toronto, Toronto, Canada, '9Department of Neurobiology and Behavior,
University of California, Irvine, USA, 30Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, USA,
31Brain Research Center, University of British Columbia, Vancouver, Canada, 32NICHD, NIH, Bethesda, USA, 3Department of Cell and Systems
Biology, University of Toronto, Toronto, Canada, 34Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo,
USA, 35Department of Basic Medicine, Kyushu University, Kyushu, Japan, 6Department of Anesthesia and Critical Care, University of Chicago,
Chicago, USA, 3Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, USA and 38Department of
Psychiatry, University of Saskatchewan, Saskatoon, Canada
Email: Guo-Qiang Bi; Vadim Bolshakov-; Guojun Bu;
Catherine M Cahill; Zhou-Feng Chen; Graham L Collingridge;
Robin L Cooper; Jens R Coorssen; Alaa El-Husseini;
Vasco Galhardo; Wen-Biao Gan; Jianguo Gu;
Kazuhide Inoue; John Isaac; Koichi Iwata;
Zhengping Jia; Bong-Kiun Kaang; Mikito Kawamata;
Satoshi Kida; Eric Klann; Tatsuro Kohno; Min Li;
Xiao-Jiang Li; John F MacDonald; Karim Nader;
Peter V Nguyen; Uhtaek Oh; Ke Ren;
John C Roder; Michael W Salter; Weihong Song;
Shuzo Sugita; Shao-Jun Tang; Yuanxiang Tao; Yu
Tian Wang ytwang@; Newton Woo; Melanie A Woodin;
Zhen Yan; Megumu Yoshimura; Ming Xu;
Zao C Xu; Xia Zhang; Mei Zhen; Min Zhuo*
* Corresponding author

Published: 30 December 2006 Received: 19 December 2006
Molecular Pain 2006, 2:38 doi:10.1 186/1744-8069-2-38 Accepted: 30 December 2006
This article is available from:
2006 Bi et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Open Access

Understanding basic neuronal mechanisms hold the hope for future treatment of brain disease. The
Ist international conference on synapse, memory, drug addiction and pain was held in beautiful
downtown Toronto, Canada on August 21-23, 2006. Unlike other traditional conferences, this
new meeting focused on three major aims: (I) to promote new and cutting edge research in
neuroscience; (2) to encourage international information exchange and scientific collaborations;
and (3) to provide a platform for active scientists to discuss new findings. Up to 64 investigators
presented their recent discoveries, from basic synaptic mechanisms to genes related to human
brain disease. This meeting was in part sponsored by Molecular Pain, together with University of
Toronto (Faculty of Medicine, Department of Physiology as well as Center for the Study of Pain).
Our goal for this meeting is to promote future active scientific collaborations and improve human
health through fundamental basic neuroscience researches. The second international meeting on
Neurons and Brain Disease will be held in Toronto (August 29-3 1, 2007).

One key factor to promote the progress of science is to
exchange scientific ideas and new discovery through meet-
ings. Scientific meeting provides critical chance for inves-
tigators to communicate new ideas, discuss different/
conflicting results, and set up potential collaborations.
Annual meeting of the American Society for Neuroscience
(SfN) has served the community well in this aspect. How-
ever, with the increased membership and the scale of the
meeting, SfN meetings only take place in a few cities in US
in a rotated manner. Due to tight security control after 9/
11, many foreign investigators failed to obtain visiting
visa to the meeting in a timely fashion. Considering these
factors, a small scale of neuroscience meeting in a more
relaxed city should provide better chance for investigators,
in particular, principal investigators (PIs) to directly com-
municate with each other, face-to-face. The 1st interna-
tional conference on synapse, memory, drug addiction
and pain is designed to meet the need. The major aim of
this meeting is to provide an opportunity for setting up
global scientific exchanges, to provide an active stage for
PIs to report novel or unpublished data, to bring neurosci-
entists working at different level of organism and systems
together, and to promote research findings from junior
and mid-career investigators.

The meeting is organized by Dr. Min Zhuo from the Uni-
versity of Toronto, with the help from Dr. Jianguo Gu
from the University of Florida, and in part sponsored by
Molecular Pain, University of Toronto (Faculty of Medi-
cine, Department of Physiology as well as Center for the
Study of Pain), and Olympus Inc.

There are four major themes for the meeting: synapse,
Synaptic plasticity, memory, pain, and brain disease.
Unlike other meetings, each speaker was given 15 min to
talk, and 5 min for discussion. The time slot allowed for
each speaker was tightly controlled by each chair (with a
timer!), and few speakers went beyond the time permit-

ted. The wine reception over the poster section provided a
wonderful opportunity for further discussions. Taking
advantage of the excellent location of the main campus in
the downtown of Toronto, attendees also enjoyed the nice
summer weather and wonderful food in Toronto. The
Niagara Fall, a famous tour site, is above 90 min drive
from the downtown of Toronto.

Students and post-doc fellows also presented over 50
posters on various topics. Among them, three posters were
selected for best poster presentations and have been
awarded with $250-500.

List of major themes, chairs, speakers and titles
Chair: Min Li (USA)

* Jens R Coorssen (University of Calgary, Calgary, Can-

The role of cholesterol in synaptic release

* Lin Mei (Medical College of Georgia, Augusta, USA)

Neuregulin regulation of neuronal activity

* Alaa El-Husseini (University of British Columbia, Van-
couver, Canada)

Mechanisms that govern protein assembly at nascent neu-
ronal contacts

* Wen-Biao Gan (New York University School of Medi-
cine, New York, USA)

Dendritic Spine Stability and Its Modification by Experi-

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Molecular Pain 2006, 2:38

* Elise F Stanley (Toronto Western Research Institute,
Toronto, Canada)

The presynaptic transmitter release site complex

Chair: Alaa El-Husseini (Canada)

* Mei Zhen (University of Toronto, Toronto, Canada)

SAD kinase regulates neuronal polarity and synapse for-

* Robin L Cooper (University of Kentucky, Lexington,

Effects of the serotonergic system on physiology, develop-
ment, learning and behavior of drosophila melanogaster

* Min Li (Johns Hopkins University, Baltimore, USA)

Chemical regulation of membrane excitability

* Shuzo Sugita (University of Toronto, Toronto, Canada)

Molecular mechanism of GTP-dependent exocytosis

* Lu-Yang Wang (University of Toronto, Toronto, Can-

Convergent pre- and post-synaptic adaptations for high-
fidelity neurotransmission at the developing calyx of Held

* Wei-Yang Lu (University of Toronto, Toronto, Canada)

Physical Interaction between Acetylcholinesterase and

Synaptic plasticity
Chair: Graham L Collingridge (UK) and Yu Tian Wang

* Eric Klann (Baylor College of Medicine, Houston, USA)

Translational Control during Hippocampal Synaptic Plas-
ticity and Memory

* Peter V Nguyen (University of Alberta, Edmonton, Can-

Beta-Adrenergic Receptors Recruit ERK and mTOR to Pro-
mote Translation-Dependent Synaptic Plasticity

* Shao-Jun Tang (University of California, Irvine, USA)

Regulation of Activity-Dependent Protein Synthesis in

* Yu Tian Wang (University of British Columbia, Vancou-
ver, Canada)

Synaptic plasticity in learning and memory

* Graham L Collingridge (University of Bristol, Bristol,

Glutamate receptors and synaptic plasticity in the hippoc-

* Michael W Salter (University of Toronto, Toronto, Can-

Ins and outs of SRC regulation of NMDA receptors and
synaptic plasticity

* John F MacDonald (University of Toronto, Toronto,

Inhibitory Regulation of the Src Hub and LTP in CA1 Hip-
pocampal Neurons

Chair: Michael W Salter (Canada)

* Vadim Bolshakov (Harvard University, Boston, USA)

Spatiotemporal asymmetry of associative synaptic plastic-
ity in fear conditioning pathways

* Guo-Qiang Bi (University of Pittsburgh, Pittsburgh,

Dynamics and plasticity of reverberatory activity in small
neuronal circuits

* Melanie A Woodin (University of Toronto, Toronto,

Bidirectional spike-timing dependent plasticity of inhibi-
tory transmission in the hippocampus

* John Isaac (NIH, Bethesda, USA)

Kainate receptors in novel forms of long-term synaptic

* Newton Woo (NIH, Bethesda, USA)

Regulation of Bi-directional Plasticity by BDNF

* Zhengping Jia (University of Toronto, Toronto, Canada)

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Molecular Pain 2006, 2:38

Molecular regulation of spine properties and synaptic

Chair: Megumu Yoshimura (Japan)

* Kazuhide Inoue (Kyushu University, Kyushu, Japan)

P2X4: mechanisms of over expression in neuropathic pain

* Jianguo Gu (University of Florida, Gainesville, USA)

TRPM8 and cold allodynia

* Uhtaek Oh (Seoul National University, Seoul, Korea)

TRPV1 and its Role for Inflammatory Pain

* Vasco Galhardo (University of Porto, Porto, Portugal)

Impairment in prefrontal-based emotional decision-mak-
ing in rat models of chronic pain

* Ke Ren (University of Maryland, Baltimore, USA)

Neuronal/glial cell interactions in CNS plasticity and per-
sistent pain

Chair: Jianguo Gu (USA)

* Yves De Koninck (Laval University, Quebec City, Can-

Plasticity of chloride homeostasis vs. plasticity of GABA/
glycine; who wins?

* Megumu Yoshimura (Kyushu University, Kyushu,

Synaptic mechanisms of acupuncture in the spinal dorsal
horn revealed by in vivo patch-clamp recordings

* Koichi Iwata (Nihon University, Tokyo, Japan)

Anterior cingulate cortex and pain -its morphological fea-
ture and functional properties

* Min Zhuo (University of Toronto, Toronto, Canada)

Cortical potentiation and its roles in persistent pain and

* Vania A Apkarian (Northwestern University, Chicago,

Chronic pain and emotional learning and memory

Chair: Uhtaek Oh (Korea)

* Zhou-Feng Chen (Washington University in St. Louis,
St. Louis, USA)

Living without serotonin: a genetic approach to study the
roles of the serotonergic system in opioid analgesia and

* Catherine M Cahill (Queen's University, Kingston, Can-

Trafficking of Delta Opioid Receptors in Chronic Pain

* Hiroshi Ueda (Nagasaki University, Nagasaki, Japan)

Molecular mechanisms of neuropathic pain lysophos-
phatidic acid as the initiator

* Yuanxiang Tao (Johns Hopkins University, Baltimore,

Are the PDZ domains at excitatory synapses potential
molecular targets for prevention and treatment of chronic

* Tatsuro Kohno (Niigata University, Niigata, Japan)

Different actions of opioid and cannabinoid receptor ago-
nists in neuropathic pain

* Ze'ev Seltzer (University of Toronto, Toronto, Canada)

Power and limitations of the comparative approach that
uses animal models to identify human chronic pain genes

* Mikito Kawamata (Sapporo Medical University School
of Medicine, Sapporo, Japan)

Genetic variation in response properties of spinal dorsal
horn neurons and rostral ventromedial medulla neurons
in different mouse strains

Brain disease
Chair: Xiao-Ming Xu (USA)

* Guojun Bu (Washington University in St. Louis, St.
Louis, USA)

LDL Receptor Family and Alzheimer's disease

* Satoshi Kida (Tokyo University of Agriculture, Tokyo,

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Molecular Pain 2006, 2:38

Mechanism of interaction between reconsolidation and
extinction of contextual fear memory

* Weihong Song (University of British Columbia, Vancou-
ver, Canada)

Hypoxia facilitates Alzheimer's disease pathogenesis

* Zhen Yan (State University of New York at Buffalo, Buf-
falo, USA)

Interactions between Acetylcholine, Amyloid and Ion
Channels in Alzheimer's Disease

* Jian Feng (State University of New York at Buffalo, Buf-
falo, USA)

Achilles' Heel of Midbrain Dopaminergic Neurons: Vul-
nerabilities and Defense Strategies

* Xiao-liang Li (Emory University, Atlanta, USA)

Synaptic toxicity of Huntington disease protein

Chair: Xiao-Jiang Li (USA)

* Fang Liu (University of Toronto, Toronto, Canada)

Regulation of dopamine reuptake by the direct protein-
protein interaction between the dopamine D2 receptor
and the dopamine transporter

* Danny G Winder (Vanderbilt University School of Med-
icine, Nashville, USA)

Synaptic plasticity in the bed nucleus of the stria termina-
lis: roles in addiction and anxiety

* Ming Xu (University of Chicago, Chicago, USA)

Molecular Mechanisms of neuronal plasticity induced by
drugs of abuse

* Xia Zhang (University of Saskatchewan, Saskatoon, Can-

TAT-3L4F, a novel peptide for the treatment of drug addic-

* Evelyn K Lambe (University of Toronto, Toronto, Can-

Hypocretin and nicotine excite the same thalamocortical
synapses in prefrontal cortex: correlation with improved
attention in rat

* Wan Qi (University of Toronto, Toronto, Canada)

Regulation of NMDA and GABA-A receptors by the tumor
suppressor PTEN

Chair: Karim Nader (Canada)

* Paul W Frankland (University of Toronto, Toronto, Can-

Functional integration of adult-born granule cells into
spatial memory networks in the dentate gyrus

* Mara Dierssen (Centre for Genomic Regulation, Barce-
lona, Spain)

Dendritic pathology and altered structural plasticity in
Down syndrome: In the search of candidate genes

* Sheena A Josselyn (University of Toronto, Toronto, Can-

Neuronal memory competition: The role of CREB

* Bong-Kiun Kaang (Seoul National University, Seoul,

Role of a novel nucleolar protein ApLLP in synaptic plas-
ticity and memory in Aplysia

* Remi Quirion (Douglas Hospital Research Centre and
INMHA, Montreal, Canada)

Novel genes possibly involved in learning and memory

Chair: Bong-Kiun Kaang (Korea)

* John C Roder (University of Toronto, Toronto, Canada)

Forward and reverse genetic screens in the mouse for
mutants impaired in learning and memory

* Karim Nader (McGill University, Montreal, Canada)

Identifying the neural mechanisms by which boundary
conditions inhibit reconsolidation from occurring.

* Yukio Komatsu (Nagoya University, Nagoya, Japan)

Role of BDNF in the production of LTP at visual cortical
inhibitory synapses

* Xiao-Ming Xu (University of Louisville School of Medi-
cine, Louisville, USA)

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Molecular Pain 2006, 2:38

Spinal cord injury repair: combinatorial strategies involv-
ing neuroprotection and axonal regeneration

* Zao C Xu (Indiana University School of Medicine, Indi-
anapolis, USA)

Synaptic plasticity in pathological conditions

* Guo-Qiang Bi (Department of Neurobiology, Univer-
sity of Pittsburgh, Pittsburgh, USA) Dynamics and
plasticity of reverberatory activity in small neuronal cir-

The concept of cell assembly was proposed by Hebb to
provide an elementary structure for thought process and
memory. The Hebbian cell assembly has two essential
properties: 1. neuronal activity can reverberate in specific
sequences within the assembly without sustained external
drive; 2. synaptic modification resulted from the reverber-
atory activity further stabilizes the reverberation. Using
whole-cell patch-clamp recording and simultaneous cal-
cium imaging, we found that brief (e.g. 1-ms) stimulation
of few neurons in a small network of about 100 cultured
hippocampal neurons could trigger reverberatory activity
in the network lasting for seconds. Such reverberatory
activity consists of repeating motifs of specific patterns of
population activation in the network. Paired-pulse stim-
uli with inter-pulse interval of ~200-400 ms are more
effective in activating such oscillatory reverberation. Fur-
thermore, repeated activation of reverberation with
paired-pulse stimuli leads to long-term enhancement of
subsequent activation by single stimuli. In addition, pair-
ing a non-effective input (that does not activate network
reverberation) into one neuron with an effective input
(that activates reverberation) into another can convert the
non-effective pathway into an effective one. Reverberatory
circuits in vitro may serve as a prototype of Hebbian cell
assembly for studies of the dynamics properties and
underlying cellular mechanisms. (Supported by NIMH
and Burroughs Wellcome Fund)

* Vadim Bolshakov (Department of Psychiatry, Harvard
University, Boston, USA) Spatiotemporal asymmetry
of associative synaptic plasticity in fear conditioning

Long-term potentiation (LTP) in afferent inputs to the
amygdala serves an essential function in the acquisition of
fear memory. The factors underlying input specificity of
synaptic modifications implicated in the information
transfer in fear conditioning pathways remain unknown.
We now show that synapses in two auditory inputs con-
verging on the same LA neuron utilize a form of the tem-
porally asymmetric learning rule when the strength of

naive synapses is only modified when a postsynaptic
action potential closely follows the synaptic response. The
stronger inhibitory drive in thalamic pathway, as com-
pared to cortical input, hampers the induction of LTP at
thalamo-amygdala synapses contributing to the spatial
specificity of LTP in convergent inputs. These results indi-
cate that spike timing-dependent synaptic plasticity in the
LA is both temporarily and spatially asymmetric, which
may contribute to the conditioned stimulus discrimina-
tion during fear behavior.

* Guojun Bu (Department of Pediatrics, and Cell Biol-
ogy and Physiology, Washington University in St.
Louis, St. Louis, USA) LDL Receptor Family and
Alzheimer's Disease

Amyloid-B peptide (Ap) production and accumulation in
the brain is a central event in the pathogenesis of Alzhe-
imer's disease (AD). Recent studies have shown that apol-
ipoprotein E (apoE) receptors, members of the low-
density lipoprotein receptor (LDLR) family, modulate AP
production as well as AP cellular uptake. AP is derived
from proteolytic processing of amyloid precursor protein
(APP), which interacts with several members of the LDLR
family. Studies from our laboratory have focused on three
members of the LDLR family, the LDLR-related protein
(LRP), LRP1B, and the LDLR. Our in vitro cellular studies
have shown that while LRP's rapid endocytosis facilitates
APP endocytic trafficking and processing to AP, LRP1B's
slow endocytosis inhibits these processes. In addition to
modulating APP endocytic trafficking, LRP's rapid endo-
cytosis also facilitates AP cellular uptake by binding to AP
either directly or via LRP ligands such as apoE. Our in vivo
studies using transgenic approach have shown that over-
expression of LRP in CNS neurons increases cell-associ-
ated AI and this increase correlates with an enhanced
memory deficits in mice. We are currently investigating
the cellular mechanisms by which LRP facilitates
intraneuronal AP accumulation, a pathological event that
directly contributes to the early cognitive deficits seen in
AD. Our preliminary results indicate that apoE plays an
important role in intraneuronal AB accumulation, likely
by shuttling AP into neurons via LRP-mediated pathways.
We hypothesize that depending on the AP species (AP 40
vs. AB 42), its aggregation states monomerss vs. oligom-
ers), and the presence of apoE isoforms (apoE3 vs.
apoE4), at least a portion of AP that is internalized via an
LRP-dependent pathway accumulates inside neurons.
Molecular and cellular models underlying the mecha-
nisms of LRP's involvements in AD will be presented and

* Catherine M Cahill (Department of Pharmacology
and Toxicology, Queen's University, Kingston, Canada)
- Trafficking of Delta Opioid Receptors in Chronic Pain

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Molecular Pain 2006, 2:38

Neuropathic (NP) pain is defined as pain caused by a
peripheral and/or central nervous system lesion with sen-
sory symptoms and signs and is estimated to affect more
than 1.5% of Americans. Despite its prevalence and
adverse impact on functionality and quality of life, it
remains a significant challenge for physicians as it is typi-
cally refractory to traditional analgesics. However research
increasingly suggests a therapeutic role of6OR agonists in
treating chronic pain. Our research aims to understand
the changes in 6OR expression and function using both in
vivo and in vitro techniques in an animal model of NP
pain. NP, but not sham-operated, rats developed cold-
and thermal-hyperalgesia as well as tactile allodynia.
Intrathecal administration of a selective 6OR agonist sig-
nificantly alleviated these nociceptive behaviours and
these effects were attenuated by a selective 6OR antago-
nist. Real-time RT-PCR and western blotting experiments
revealed no change in overall expression of 6OR in the
dorsal spinal cord however preliminary studies suggest
that induction of NP pain may induce changes in subcel-
lular localization of 6ORs leading to enhanced analgesia.

* Zhou-Feng Chen (Department of Anesthesiology,
Washington University in St. Louis, St. Louis, USA) -
Living without serotonin: a genetic approach to study
the roles of the serotonergic system in opioid analgesia
and tolerance

Narcotics have long been used as an effective treatment for
pain. The roles of the serotonergic (5-HT) system in opi-
oid analgesia and tolerance, however, have been contro-
versial. We have recently shown that the transcription
factor Lm x lb is essential for the development of 5-HT
neurons. In the absence of Lm x lb, all 5-HT neurons
failed to develop in the raphe system. Because Lm x lb-
null mice die around birth, we have designed to strategy
to delete Lm x lb in 5-HT neurons only. Lm x lb condi-
tional knockout (CKO) mice lack all 5-HT neurons in the
raphe system. Surprisingly, Lm x lb CKO mice survive to
the adulthood without motor deficiency. To assess the
roles of the 5-HT system in opioid analgesia, we have
examined the tail-flick responses of Lm x lb CKO mice
injected with mu-, kappa- and delta-opioid receptor ago-
nists. In addition, we also examined the site of action of
opioid receptor agonists by systemic, intrathecal and
intracerebroventricular injections. These pharmacological
studies revealed that the 5-HT system contributes differen-
tially to opioid analgesia. Moreover, an examination of
morphine analgesic tolerance in Lm x lb CKO mice indi-
cated that morphine tolerance is independent of the 5-HT
system. These results should have important implications
in our understanding of mechanisms of action for the 5-
HT system in opioid analgesia and tolerance.

* Graham L Collingridge (Centre for Synaptic Plasticity,
University of Bristol, Bristol, UK) Kainate receptors:
Functions and the discovery of novel antagonists.

Less is known about the role of kainate receptors com-
pared with the other classes of ionotropic glutamate
receptors in the CNS. However, recent studies, mainly
employing the Lilly antagonist, LY3 82884, have identified
several functions: For example, at mossy fibre synapses in
the hippocampus these receptors function as facilitatory
autoreceptors and are involved the induction of LTP. Kai-
nate receptors also contribute to synaptic transmission at
this synapse. Elsewhere kainate receptors can function as
inhibitory autoreceptors and can regulate GABA transmis-

Whilst LY382884 is a very useful antagonist it has a rela-
tively narrow selectivity for GluR5-containing kainate
receptors versus AMPA receptors. David Jane and his col-
leagues in Bristol have therefore developed a series of
highly potent and specific GluR5 antagonists, the most
potent of which is ACET. This compound should be
extremely useful in investigating the role of kainate recep-
tors in physiological and pathological functions in the
CNS, for example, in neurodegeneration and neuropathic

* Robin L Cooper (Department of Biology, University
of Kentucky, Lexington, USA) Effects of the serotoner-
gic system on physiology, development, learning and
behavior of drosophila melanogaster

The serotonergic system in nervous tissue is known to play
a vital role in development and behavior in simple to
complex animal models. Using a simple model organism,
Drosophila, the importance of serotonin (5-HT) circuitry
in development and acute actions can be addressed. Also
there are only four 5-HT receptors in the Drosophila
genome, of which 5-HT2dro is known to be essential in
the embryonic stages of development. Previously we have
shown a physiological sensitivity of exogenous applica-
tion of 5-HT on a sensory-CNS-motor circuit in semi-
intact preparations of 3rd instar larvae. Now, using phar-
macological manipulations and available receptor
mutants for 5-HT2dro, we are studying the role of 5-HT in
development, behavior and physiology of 3rd instar lar-
vae. Para-chlorophenylalanine (p-CPA), is a blocker of 5-
HT biosynthesis pathway and 3,4-Methylenedioxymeth-
amphetamine (MDMA, Ecstasy), is a common drug of
abuse in humans, which is known to compel mammalian
serotonergic neurons to release 5-HT. When fed these
compounds from 1st to 3rd instar a slowing of the growth
occurred in a dose dependent manner. The rate of body
wall and mouth hook movements were reduced in p-CPA
and MDMA fed larvae. HPLC results showed lower

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Molecular Pain 2006, 2:38

amounts of 5-HT in larval brains for p-CPA but not
MDMA fed larvae. An increase in sensitivity of sensory-
CNS-motor circuit to 5-HT in drug fed larvae appears to be
due an up regulation of 5-HT receptors. The antisense line
for 5-HT2dro receptor also produces a delay in larval
development. Preliminary data shows an impaired associ-
ative gustatory and olfactory learning behaviors in 3rd
instar larvae with lower 5-HT or reduced expression of the
5-HT2dro receptor.

* Jens R Coorssen (Department of Physiology and Bio-
physics, University of Calgary, Calgary, Canada) -The
role of cholesterol in synaptic release

Fast, Ca2+ -triggered membrane merger defines regulated
exocytosis. In native secretary vesicles, cholesterol
(CHOL) functions in the fundamental fusion mechanism,
and CHOL/sphingomyelin enriched microdomains
define the efficiency (Ca2+ sensitivity and kinetics) of
fusion. The role of CHOL in the fusion mechanism is
mimicked by structurally dissimilar lipidic membrane
components having spontaneous negative curvature (/
NC/) = CHOL, and correlates quantitatively with the/NC/
each contributes to the membrane (e.g. a-tocopherol and
dioleoylphosphatidylethanolamine). Unable to substi-
tute for CHOL in rafts, these lipids do not rescue fusion
efficiency. Lipids of spontaneous/NC/< CHOL (e.g. diole-
oylphosphatidic acid), do not support fusion. We have
also identified com-parable molecular dependencies and
relationships at the synapse, suggesting a conserved role
for CHOL and the/NC/contributed. This quantitative rela-
tionship between/NC/and fusion appears most consistent
with the stalk-pore model, demonstrating that/NC/itself
is an essential component of the fundamental native
fusion mechanism. The data also suggest that different
fusion sites, vesicles, or secretary cells can use other lipidic
components, in addition to sterols, to provide optimal
local/NC/and even to modulate the fusion process.

* Alaa El-Husseini (Department of Psychiatry, Univer-
sity of British Columbia, Vancouver, Canada) Elabo-
ration of dendritic filopoidia is not a rate-limiting step
for production of stable axonal-dendritic contacts.

Dendritic filopodia are thought to play an active role in
synaptogenesis and serve as precursors to spine synapses.
However, this hypothesis is largely based on a temporal
correlation between the onset of filopodia elaboration
and synaptogenesis. We have previously demonstrated
that the palmitoylated protein motifs of GAP-43 and para-
lemmin are sufficient to increase the number of filopodia
and dendritic branches in neurons. Here we examined
whether filopodia induced by these motifs, as well as
those induced by cdc42 lead to the formation of stable
synaptic contacts and the development of dendritic

spines. Our analysis shows that expression of these filopo-
dia inducing motifs (FIMs) or the constitutively active
form of cdc-42 enhances filopodia motility, but reduces
the probability of forming a stable axon-dendrite contact.
Conversely, expression of neuroligin-1 a synapse inducing
cell adhesion molecule, resulted in a decrease in filopodia
motility, an increase in the number of stable axonal con-
tacts, and the recruitment of synaptophysin positive trans-
port packets. Postsynaptic scaffolding proteins such as
Shank-1 that induce the maturation of spine synapses
reduced filopodia number, but increased the rate at which
filopodia transformed into spines. By following individ-
ual dendrites over a 2-day period we determined that rel-
atively few sites with filopodia are replaced by spine
synapses (~3%). These results suggest that high levels of
filopodia elaboration and motility may not necessarily be
a rate-limiting step for synapse formation, and that factors
that control filopodia-process dynamics may participate
in synapse formation by rapid stabilization of the initial
contact between dendritic filopodia and axons.

* Vasco Galhardo (Institute for Molecular and Cell Biol-
ogy, University of Porto, Porto, Portugal) Impairment
in prefrontal-based emotional decision-making in rat
models of chronic pain

Chronic pain is known to cause several cognitive deficits
in human subjects. Among these deficits is the incapabil-
ity of performing correctly in decision-making tasks that
have a risk component, such as rewards of variable value.
This cognitive impairment is known to occur after amy-
gdalar or orbitofrontal lesions, where individuals are inca-
pable of long-term planning and take high-risk decisions
even if they lead to overall losses. It was recently shown
that chronic pain patients also present this pattern of
impaired decision-making (Apkarian et al, Pain, 108:129,
2004). However, no studies in chronic pain animal mod-
els have addressed poor performance in frontal-based cog-
nitive tasks. For this reason we developed a novel
behavioral task based on repetitive reward-based simple
decisions, and studied its performance by both control,
frontal-lesioned, and chronic pain animals (n = 6 per
group). The task consisted on consecutive trials in which
a rat entered an operant chamber and had to choose
between two levers to recover a food reward. After each
trial, the animal was removed to a contiguous chamber
where he waited for a sound signal to begin a new trial.
During the 15 days of the training phase both levers gave
equal pseudo-random rewards: one food pellet in 8 of 10
presses, and no reward in the other two low risk. In the
trial probe one of the levers was modified to give 3 food
pellets, but only in 3 of 10 visits high risk. The pattern
of 120 consecutive choices was used to calculate the lever-
choice index (low risk minus high risk, divided by
number of completed trials). In the first 60 trials all the

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Molecular Pain 2006, 2:38

animals (controls, lesioned and monoarthritic) reverently
choose the large reward lever, but control animals
reversed the pattern of choice in the second half of the ses-
sion. When analyzing the last 30 entries, controls had a
choice index of +0.42 0.17, while monoarthritic rats had
-0.48 0.14, neuropathic rat had -0.53 + 0.21 and frontal-
lesioned animals -0.58 + 0.31. We have shown for the first
time that chronic pain induces complex changes in the
cognitive neural processes that handle immediate deci-
sion-making in the rat (Support: FCT-POCI/55811/

* Wen-Biao Gan (Skirball Institute, New York Univer-
sity School of Medicine, New York, USA) Dendritic
Spine Stability And Its Modification By Experience

The nervous system requires not only synaptic plasticity
for learning but also stability for long-term information
storage. To study the degree of synaptic structural plastic-
ity in intact animals, we developed a transcranial two-
photon imaging technique to follow individual postsyn-
aptic dendritic spines over time in transgenic mice over-
expressing Yellow Fluorescent Protein. Using this tech-
nique, we found that in young adolescent mice (1-month-
old), 13-20% of spines were eliminated and 5-8% were
formed over 2 weeks in visual, barrel, motor and frontal
cortices, indicating a cortical-wide loss of spines during
this developmental period. In adult mice (4-6 months
old), 3-5% of spines were eliminated and formed over 2-
4 weeks in various cortical regions. When imaged over 19
months, only 26% of adult spines were eliminated and
19% were formed in barrel cortex. Thus, after a concurrent
reduction in the number of spines in the diverse regions
of young adolescent cortex, spines become remarkably
stable and a majority of them can last throughout life.

To determine how spine dynamics are modified by expe-
rience, we examine the effect of long-term sensory depri-
vation via whisker trimming on dendritic spines in the
barrel cortex. During young adolescence when a substan-
tial net loss of spines occurs, we found that whisker trim-
ming preferentially reduces the rate of on-going spine
elimination than spine formation. This effect of depriva-
tion diminishes as animals mature but still persists in
adulthood. In addition, restoring sensory experience fol-
lowing adolescent deprivation accelerates spine elimina-
tion but has no significant effect on spine formation. The
rate of spine elimination also decreases after chronic
blockade of NMDA receptors with the antagonist MK801
and accelerates after drug withdrawal. These studies
underscore the important role of sensory experience in
spine elimination over the majority of an animal's life
span, particularly during adolescence.

* Jianguo Gu (Department of Oral and Maxillofacial
Surgery, University of Florida, Gainesville, USA) -
TRPM8 and cold allodynia

Peripheral nerve injury often results in neuropathic pain
manifested with both mechanical and thermal allodynia.
Thermal allodynia of neuropathic pain conditions
includes cold- and heat allodynia. While TRPV1 is found
to be involved in heat allodynia, molecular mechanisms
of cold allodynia remain unclear. Recently, transient
receptor potential channel M8 (TRPM8 receptor) is found
to be a cold- and menthol-sensing receptors expressed on
a subpopulation of primary afferent fibers. Here we report
the upregulation ofTRPM8 expression on nociceptive-like
afferent neurons following chronic constrictive nerve
injury (CCI) rats that manifested with cold allodynia. We
found not only the number ofTRPM8-expressing neurons
was increased, but also the responsiveness to cold and
menthol became enhanced in these afferent neurons fol-
lowing CCI. These results suggest TRPM8 upregulation is
associated with cold allodynia and may be an underlying
mechanism of cold allodynia

* Kazuhide Inoue (Department of Pharmaceutical
Health Care and Sciences, Kyushu University, Kyushu,
Japan) P2X4: mechanisms of over expression in neu-
ropathic pain state

There is abundant evidence that extracellular ATP and
other nucleotides have an important role in pain signaling
at both the periphery and in the CNS. Recent findings sug-
gest that endogenous ATP and its receptor system might
be involved in neuropathic pain. Neuropathic pain is
often a consequence of nerve injury through surgery, bone
compression, diabetes or infection. This type of pain can
be so severe that even light touching can be intensely
painful; unfortunately, this state is generally resistant to
currently available treatments. We recently reported that
the expression of P2X4 receptors in the spinal cord is
enhanced in spinal microglia after peripheral nerve injury,
and blocking pharmacologically and suppressing molecu-
larly P2X4 receptors produce a reduction of the neuro-
pathic pain behaviour (Nature 424,778-783, 2003), and
that brain-derived neurotrophic factor (BDNF) released
from microglia by the stimulation of P2X4 causes the
depolarizing shift in reversal potential of anion in LI neu-
rons of rats with nerve injury (Nature, 438, 1017-1021,
2005), resulting in causing neuropathic pain. Under-
standing the key roles of these ATP receptors may lead to
new strategies for controlling the pain.

* John Isaac (NINDS, NIH, Bethesda, USA) Rapid,
Activity-Dependent Plasticity in Timing Precision in
Neonatal Barrel Cortex

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Molecular Pain 2006, 2:38

During development neuronal networks acquire the abil-
ity to precisely time events. This is a critical developmental
step since precise timing is required for information
processing and plasticity in the adult brain. Despite this it
is not known what process drives this maturation in tim-
ing. I will present recent work from my laboratory show-
ing that long-term potentiation (LTP) induced at
thalamocortical synapses in neonatal layer IVbarrel cortex
produces a rapid and dramatic improvement in input and
output timing precision. LTP reduces the latency and var-
iability of synaptically-evoked action potentials and
reduces co-incidence detection for synaptic input. In con-
trast, LTP has only a small and variable effect on synaptic
efficacy. This improvement in timing occurs during devel-
opment, suggesting this process occurs in vivo in the
developing barrel cortex. Thus, rather than increasing syn-
aptic efficacy, the primary role of this form of neonatal
LTP is to enable neurons to precisely time events.

* Koichi Iwata (Department of Physiology, Nihon Uni-
versity, Tokyo, Japan) Anterior cingulate cortex and
pain -its morphological feature and functional proper-

It is well known that the anterior cingulate cortex (ACC)
has a variety of functions related to pain including pain
perception. Many ACC neurons respond to noxious and
non-noxious stimulation of the body. Most of these neu-
rons have a large receptive field and increase their firing
frequency as stimulus intensity increases. ACC nocicep-
tive neurons have very specific morphological features,
such as a small soma and a large number of spines on the
dendritic trees, and axon collaterals spreading over a wide
area of the ACC. In a retrograde trans-synaptic tracing
study, we found that ACC neurons receive predominantly
A-delta afferents inputs. We also analyzed the responses of
ACC nociceptive neurons in awake behaving monkeys. A
small number of ACC neurons modulated their activity
during noxious heating of the facial skin. The neuronal
activity was significantly higher when monkeys escaped
from a noxious heat stimulus than when the monkeys
detected a small change in temperature (T2) above a larger
initial shift (T1). No relationship between firing fre-
quency and detection latency of the T2 stimulation was
observed. These findings suggest that ACC nociceptive
neurons are involved in attention to pain and escape from
pain, but not in the sensory-discriminative aspect of pain.

* Zhengping Jia (Department of Physiology, University
of Toronto, Toronto, Canada) Molecular regulation of
spine properties and synaptic plasticity

The dendritic spine is the major postsynaptic site of exci-
tatory synapse and its changes are linked to synaptic plas-
ticity, memory formation and various forms of mental

and neurological disorders. However, the molecular
mechanisms that govern spine development and regula-
tion are poorly defined. We take genetic approaches in
mice to identify and characterize the molecular signaling
processes involved in the regulation of spine formation,
spine morphology, and spine and synaptic plasticity. Spe-
cifically, we are interested in the signal transduction path-
ways stimulated by the Rho family small GTPases, key
mediators of actin dynamics in response to various exter-
nal stimuli. Our objective is to define the in vivo function
and synaptic regulation of Rho signaling in the context of
spine properties, hippocampal long-term potentiation
and fear memory formation. The specific roles and the
underlying mechanisms of various components required
for normal Rho signaling will be discussed.

* Bong-Kiun Kaang (Department of Biological Sciences,
Seoul National University, Seoul, Korea) Role of a
novel nucleolar protein ApLLP in synaptic plasticity
and memory in Aplysia

In Aplysia long-term synaptic plasticity is induced by sero-
tonin (5-HT) or neural activity, and requires gene expres-
sion. Here, we demonstrate that ApLLP, a novel nucleolus
protein is critically involved in both long-term facilitation
(LTF) and behavioral sensitization. Membrane depolari-
zation induced ApLLP expression, which activated ApC/
EBP expression through a direct binding to CRE. LTF was
produced by a single pulse of 5-HT 30 min after the mem-
brane depolarization. This LTF was blocked when either
ApLLP or ApC/EBP were blocked by specific antibodies. In
contrast, ApLLP overexpression induced LTF in response
to a single 5-HT treatment. Simultaneously, a siphon nox-
ious stimulus (SNS) to intact Aplysia induced ApLLP and
ApC/EBP expression, and single tail shock 30 min after
SNS transformed short-term sensitization to long-term
sensitization of siphon withdrawal reflex. These results
suggest that ApLLP is an activity-dependent transcrip-
tional activator that switches short-term facilitation to
long-term facilitation

* Mikito Kawamata (Department of Anesthesiology,
Sapporo Medical University School of Medicine, Sap-
poro, Japan) Genetic variation in response properties
of spinal dorsal horn neurons and rostral ventromedial
medulla neurons in different mouse strains

Although various methods of analgesia are currently used
for persistent pain such as inflammatory pain and neuro-
pathic pain, optimal pain therapy has still not been estab-
lished. This may be at least in part related to variability of
perceived pain among patients. Recent behavioral studies
have shown that nociception in the mouse is heritable,
which may reflect variable sensitivity to tissue injury-
induced pain in humans (Mogil et al., 1996). Noxious

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information is transmitted through fine myelinated A6
and unmyelinated C afferents from the periphery to the
superficial dorsal horn (SDH), especially to the substantial
gelatinosa (SG, lamina II of Rexed) (Light and Perl, 1979).
This sensory information is modified and integrated in
the SG and consequently regulates the outputs of projec-
tion neurons located in lamina I and laminae V-VI (Cer-
vero and Iggo, 1980; Eckert et al., 2003). In addition, the
descending inhibitory influences from supraspinal struc-
tures, including the rostral ventromedial medulla (RVM),
on SDH neurons are known to be modified under certain
pathological conditions (Basbaum, 1973; Dubuisson and
Wall, 1980; Laird and Cervero, 1990; Sandkuhler et al.,
1995; Wall et al., 1999).

Thus, nociceptive network circuits in the central nervous
system, including the SDH and RVM, may play an impor-
tant role in different pain sensitivity in individuals. Our
hypothesis is that SDH neurons and RVM neurons in dif-
ferent mouse strains may show different response proper-
ties following tissue injury and different sensitivity to
analgesics depending on different genetic background. In
order to prove this hypothesis, in vivo extracellular record-
ings and in vivo whole-cell patch-clamp recordings were
made from SDH neurons located in deep laminae (lami-
nae V-VI) and from superficial SDH neurons located in
lamina II, respectively, in different strains of mice (A/J,
C57BL/6J, and CBA/J strains) before and after tissue injury
induced by surgical incision and formalin injection
according to previously described methods (Furue et al.,
1999; Kawamata et al, 2005). In a separate study, single
neuronal activity was isolated from different types of RVM
neurons such as ON cells, OFF cells and NEURTRAL cells,
and response properties of these neurons were deter-
mined before and after intraventricular injection of
DAMGO or surgical injury.

The results have shown that different mouse strains have
different sensitivities to postoperative pain and formalin-
induced pain, reflecting different characteristics of SDH
neurons in the strains following surgical incision and
application of formalin. Responses of RVM neurons were
also different in different mouse strains following surgical
injury and that different mouse strains have different sen-
sitivities to morphine application. The results suggest that
pain intensity and pain mechanisms depend at least in
part on genetic background of the individual. Further-
more, mechanisms of pain seen in a clinical setting may
thus differ in individuals depending on the response
properties of SDH neurons and RVM neurons.

* Satoshi Kida (Department of Agricultural Chemistry,
Tokyo University of Agriculture, Tokyo, Japan) Mech-
anism of interaction between reconsolidation and
extinction of contextual fear memory

Retrieval of conditioned fear memory initiates two poten-
tially dissociable but opposite processes; reconsolidation
and extinction. Reconsolidation acts to stabilize, whereas
extinction tends to weaken the expression of the original
fear memory. To understand the mechanisms for the reg-
ulation of memory stability after the retrieval, we have
investigated the relationship between reconsolidation
and extinction using contextual fear conditioning, associ-
ative learning between context (conditioned stimulus;
CS) and fear (unconditioned stimulus; US). We first
examined effects of duration of re-exposure to CS on
memory reconsolidation and extinction. Protein synthesis
inhibition following short re-exposure (3 min) to CS dis-
rupted the contextual fear memory, indicating short re-
exposure induces memory reconsolidation. In contrast,
protein synthesis inhibition following long-re-exposure
(30 min) blocked memory extinction. Importantly, in
extinction phases, contextual fear memory was intact even
though protein synthesis was inhibited. Therefore, these
observations suggested the interaction between memory
reconsolidation and extinction phases. Indeed, memory
extinction seems to be associated with regulation of fear
memory stability after retrieval.

To further understand how extinction phase interacts with
reconsolidation phase, we assume that molecules func-
tioning on one phase should also function on another
phase if interaction between reconsolidation and extinc-
tion phases is observed at the molecular level. Therefore,
we compared molecular signatures of these processes
using pharmacology and mouse genetics. Pharmacologi-
cal experiments using antagonists for cannabinoid recep-
tor 1 (CB1) and L-type voltage-gated calcium channels
(LVGCCs), that play essential roles in memory extinction,
indicated that both CB1 and LVGCCs are required for
memory extinction but not consolidation and reconsoli-
dation. More importantly, double injection of anisomy-
cin and antagonists for either CB 1 or LVGCCs prevents the
disruption of the original memory by protein synthesis.
These results suggest that CB1 and LVGCCs are required
for not only memory extinction but also the destabiliza-
tion of reactivated memory. We are now trying similar
experiments using conditional CREB mutant mice.

In addition, to compare the brain regions associated with
reconsolidation and extinction, we analyzed brain regions
showing increase in CREB activity in reconsolidation and
extinction phases by immunocytochemistry. We observed
increase in phosphorylated CREB at serine 133 in amy-
gdala and hippocampus following short re-exposure to CS
inducing memory reconsolidation and in amygdala and
prefrontal cortex following long re-exposure to CS induc-
ing memory extinction. These observations suggest that
acquisition of memory extinction prevent the activation

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Molecular Pain 2006, 2:38

of hippocampus, resulting in preservation of contextual
fear memory.

Taken together, these our findings indicate the interaction
between memory extinction and regulation of memory
stability at the molecular, anatomical and behavioral
level. Further understanding the mechanisms of this inter-
action might make more clearly understand the signifi-
cance of memory reconsolidation.

* Eric Klann (Department of Molecular Physiology and
Biophysics, Baylor College of Medicine, Houston, USA)
- Translational Control During Hippocampal Synaptic
Plasticity and Memory

Altered gene expression is a hallmark of long-lasting syn-
aptic plasticity and long-term memory. Regulation of
local protein translation permits synapses to control syn-
aptic efficacy independently ofmRNA synthesis in the cell
body. Recent studies, including several from this labora-
tory, have identified biochemical signaling cascades that
couple neurotransmitter and neurotrophin receptors to
the translation regulatory machinery in translation-
dependent forms of synaptic plasticity and memory. In
this presentation, these translation regulatory mecha-
nisms and the signaling pathways that govern the expres-
sion of various forms of translation-dependent synaptic
plasticity and memory will be discussed. In addition, syn-
aptic plasticity and memory deficits in genetically engi-
neered mice that lack specific translation factors and
translation regulatory proteins will be discussed. These
studies have revealed interesting links among the bio-
chemical activities of translation factors, synaptic plastic-
ity, and memory that are likely to be important for other
forms of plasticity and behavior, such as those that under-
lie pain and drug addiction.

* Tatsuro Kohno (Division of Anesthesiology, Niigata
University, Niigata, Japan) Different actions of opioid
and cannabinoid receptor agonists in neuropathic pain

Peripheral nerve injury causes neuropathic pain, which is
characterized by hyperalgesia and allodynia to mechani-
cal and thermal stimuli. Neuropathic pain has tradition-
ally been considered opioid-resistant to intrathecal
opioids; however, the efficacy of opioid in treating neuro-
pathic pain is controversial. In contrast, increasing evi-
dence indicates that cannabinoids are effective in
alleviating neuropathic pain. We evaluated the effect of
opioids and cannabinoids in two independent partial
peripheral nerve injury models, the spared nerve injury
(SNI) and the spinal nerve ligation (SNL) models. In both
the SNI and SNL rat peripheral neuropathic pain models
the presynaptic inhibitory effect of the g opioid receptor
(MOR) agonist (DAMGO) on primary afferent-evoked

excitatory postsynaptic currents (EPSCs) and miniature
EPSCs in superficial dorsal horn neurons is substantially
reduced, but only in those spinal cord segments inner-
vated by injured primary afferents. The two nerve injury
models also reduce the postsynaptic potassium channel
opening action of DAMGO on lamina II spinal cord neu-
rons, but again only in segments receiving injured afferent
input. The inhibitory action of DAMGO on ERK (extracel-
lular signal-regulated kinase) activation in dorsal horn
neurons is also reduced in affected segments following
nerve injury. MOR expression decreases substantially in
injured dorsal root ganglion neurons (DRG), while intact
neighboring DRGs are unaffected. In contrast to MOR
agonist, the selective CB1 receptor agonist (ACEA) still
suppressed C-fiber-induced ERK activation in dorsal horn
neurons in injured spinal cord segments from SNL rats.
These studies suggest that opioids may reduce sensitivity
in those patients whose pain is generated mainly from
injured nociceptor discharge. However, opioid may still
be able to suppress neuropathic pain via acting on intact
primary afferents or via supraspinal mechanisms. Because
the efficacy of cannabinoid in suppressing C-fiber-
induced ERK expression fully remains in the injured spi-
nal segments after nerve ligation, our results support an
undiminished potency of cannabinoid in attenuating
neuropathic pain. Our data also suggest that there might
be different regulatory mechanisms of opioids and can-
nabinoids for neuropathic pain.

* Min Li (Department of Neuroscience and High
Throughput Biology Center, Johns Hopkins University,
Baltimore, USA) Chemical regulation of membrane

Biological phenomena ranging from neuronal action
potential, to rhythmic cardiac contraction, to sensory
transduction, to hormone secretion are ultimately con-
trolled by one class of proteins: the ion channels. Changes
of ion channel activities by genetic mutations or by drugs
are causes for human diseases and basis for therapeutics.
Potassium channels are critical to a variety of biological
processes and represent a very large class of ion channel
proteins permeable to potassium ions. Of the more than
400 ion channel genes in the human genome, at least 167
are annotated potassium channels.

The regulation and biogenesis of potassium channels are
important processes essential to the understanding of
their physiological roles. Recent evidence indicates that
cardiotoxicity of many human drugs for other intended
targets is caused by inhibition of a subset of potassium
channels through different mechanisms. These drugs are
both chemically stable and economically available. There-
fore, they represent useful chemical probes to investigate
potassium channel regulation both at the molecular level

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Molecular Pain 2006, 2:38

and at the cell biological level. Using a combination of
high throughput chemical biology approaches and
detailed biochemical and electrophysiological analyses,
we have screened and identified a number of regulatory
compounds with unique mechanisms of action in regulat-
ing potassium channels.

* Xiao-Jiang Li (Department of Human Genetics, Emory
University, Atlanta, USA) Synaptic toxicity of Hunt-
ington disease protein

Huntington's disease (HD) is characterized by the selec-
tive loss of striatal projection neurons. In early stages of
HD, neurodegeneration preferentially occurs in the lateral
globus pallidus (LGP) and substantial nigra (SN), two
regions where the axons of striatal neurons terminate. The
unique neuronal structure, which is characterized by
numerous neuronal processes that interact with each
other at their terminals, may confer the preferential vul-
nerability to expanded polyQ proteins. In HD mice that
precisely and genetically mimic the expression of full-
length mutant huntingtin (htt) in HD patients, we found
that degraded N-terminal fragments of htt preferentially
forms aggregates in striatal neurons that are most affected
in HD. More importantly, neuropil aggregates form pref-
erentially in the processes of striatal neurons. In HD trans-
genic mice that express N-terminal mutant htt, the
progressive formation of these neuropil aggregates corre-
lates with disease progression. We also observed degener-
ated axons in which htt aggregates were associated with
dark, swollen organelles that resemble degenerated mito-
chondria. These findings suggest that the early neuropa-
thology of HD originates from axonal dysfunction and
degeneration associated with htt neuropil aggregates.

* John F MacDonald (Department of Physiology, Uni-
versity of Toronto, Toronto, Canada) Inhibitory Reg-
ulation of the Src Hub and LTP in CA1 Hippocampal

The induction of long-term potentiation (LTP) at CA1
synapses of the hippocampus requires an influx of Ca2+
via N-methyl-d-aspartate receptors (NMDARs). High fre-
quency stimulation depolarizes CA1 neurons, relieving
the voltage-dependent block of NMDARs by Mg2+, per-
mitting the entry of Ca2+ that is critical for this induction.
Thus, NMDARs serve as co-incident detectors of the LTP-
inducing afferent input to CA1 neurons. Enhanced activa-
tion of the non-receptor tyrosine kinase Src is also
required for this co-incidence function; and, Src is the
convergent target of a variety of G-protein coupled recep-
tors (GPCRs) of the Ga q family (e.g. LPA, muscarinic,
mGluR5 and PACAP receptors). These GPCRs stimulate a
Src-dependent upregulation of NMDARs via a sequential
activation of PKC and the non-receptor tyrosine kinase,

Pyk2 which is also required for induction of LTP. Src
therefore acts as a hub for the regulation of the induction
of LTP at CA1 synapses.

Signaling pathways which inhibit Src, and thereby inhibit
the induction of LTP, have not been extensively studied.
We have previously shown that platelet-derived growth
factor receptors (PDGFRB) inhibit NMDARs in CA1 neu-
rons by a PKA-dependent but Src-permissive mechanism.
For example, in inside-out patches from cultured hippoc-
ampal neurons PKA fails to inhibit NMDAR channel activ-
ity unless it is first enhanced with a Src-activator peptide.
Furthermore, we show that in hippocampal slices
PDGFBB (receptor ligand) inhibits the induction of LTP.
The initial step in this pathway requires tyrosine phospho-
rylation of tyrosine 1021 of the PDGFR which forms a
SH2 docking site for PLCy. PLCy interacts with another
non-receptor kinase, Abelson kinase (Abl) which among
other activities regulates PDGFR activity via a biochemical
feedback. In recordings from single isolated CA1 pyrami-
dal neurons we show that intracellular applications of Abl
kinase strongly inhibit currents evoked by applications of
NMDA. This inhibition is reversibly blocked by extracellu-
lar applications the PDGFR antagonist gleevec demon-
strating the dependency of this response on PDGFR
activity. How PDGFR, PLCy and Abl kinase activity trans-
lates into inhibition of NMDARs is not fully understood
and is currently under investigation.

* Karim Nader (Department of Psychology, McGill Uni-
versity, Montreal, Canada) Identifying the neural
mechanisms by which boundary conditions inhibit
reconsolidation from occurring.

Although memory reconsolidation has been demon-
strated in various learning tasks and animal models sug-
gesting it is a fundamental process, reports of boundary
conditions imply that reconsolidation is not ubiquitous.
These boundary conditions, however, remain poorly
defined at the behavioral, systems and molecular levels.
Attempting to ameliorate this situation, we characterized
reconsolidation of strong memories across all three levels
of analysis. At the behavioral level we demonstrated that
this boundary condition is transient, as infusions of ani-
somycin into lateral and basal amygdala in rats did not
impair reconsolidation of overtrained auditory fear mem-
ories after 2 or 7 days, but did so after 30 or 60 days after
training. At the systems level we showed that the hippoc-
ampus imposes the boundary condition on the amygdala,
as the overtrained memory underwent reconsolidation 2
days after training in animals with pretraining dorsal hip-
pocampus lesions. At the molecular level we demon-
strated that the degree of expression of NR2B-containing
NMDA receptors in the amygdala modulates reconsolida-
tion of overtrained fear memories, as these receptors,

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Molecular Pain 2006, 2:38

which we previously have identified as being essential for
the transformation of a consolidated memory back to a
labile state, were down-regulated 2, but not 60 days after
overtraining; furthermore, animals with pre-training hip-
pocampus lesions, that did not exhibit the overtraining
boundary conditions two days after training, had normal
level of expression of NR2B subunits at that time-point.
These findings make three conceptual advances in our
understanding of reconsolidation: first, boundary condi-
tions can be transient, second, boundary conditions can
be imposed by other brain systems, and third, a mecha-
nism mediating the manifestation of boundary condi-
tions is down-regulation of the receptors that are critical
for inducing reconsolidation.

* Peter V Nguyen (Department of Physiology, Univer-
sity of Alberta, Edmonton, Canada) Beta-Adrenergic
Receptors Recruit ERK and mTOR to Promote Transla-
tion-Dependent Synaptic Plasticity

A key question in neuroscience research is: How does acti-
vation of neuromodulatory receptors initiate protein syn-
thesis during long-term synaptic plasticity? Activation of
beta-adrenergic receptors can enhance long-term memory
and modulate long-term synaptic plasticity in the mam-
malian hippocampus. Protein synthesis is required for the
persistence of long-term potentiation (LTP) and for the
consolidation of long-term memory. However, the intrac-
ellular signaling cascades that couple beta-adrenergic
receptors to translation initiation and subsequent protein
synthesis are unidentified. We used electrophysiological
recordings in area CA1 of mouse hippocampal slices to
investigate the recruitment of signaling cascades necessary
for beta-adrenergic LTP. We found that maintenance of
this LTP requires the extracellular signal-regulated kinase
(ERK) and mammalian target ofrapamycin (mTOR) path-
ways, but not cAMP-dependent protein kinase (PKA).
Consistent with these findings, treatment of hippocampal
slices with isoproterenol, a beta-adrenergic agonist,
increases phosphorylation of eukaryotic initiation factor
4E (eIF4E), the eIF4E kinase Mnkl, and the translation
repressor, 4E-BP2. These translational regulators can be
phosphorylated in an ERK- and mTOR-dependent man-
ner. Moreover, activation of beta-adrenergic receptors
eliminates deficits in late-LTP seen in transgenic mice that
express reduced hippocampal PKA activity. Our results
identify specific intracellular signaling pathways that link
beta-adrenergic receptor activation at the membrane to
translation initiation within the cytosol. More impor-
tantly, our data reveal a molecular mechanism for neuro-
modulatory control of protein synthesis during LTP, a
process that is required for the formation of long-lasting
memories. [Funded by Alberta Heritage Fdn. for Med. Res.
and CIHR, NIH, NIMH, and the Fragile X Research Fdn].

* Uhtaek Oh (Sensory Research Center, Seoul National
University, Seoul, Korea) TRPV1 and its Role for
Inflammatory Pain

Capsaicin (CAP) is a pungent ingredient in hot peppers.
CAP has a unique action on the pain sensory system. CAP
causes a pain when applied to the skin. The hyperalgesic
action of CAP is mediated by the excitation of sensory
neurons. CAP is known to activate ion channels that allow
cation influxes, thus, depolarizing sensory neurons. CAP-
activated ion channel along with its channel property was
identified. The channel is a ligand-gated channel and per-
meable to various cations. The gene encoding for the CAP
sensitive current was cloned and dubbed as VR1 (vanil-
loid receptor 1). Primary structure of VR1 shows that VR1
belongs to transient receptor potential (TRP) channel
family, having 6 transmembrane domains with two long
cytosolic amino acid sequences in each N- or C- terminus.
According to the recently classified nomenclature, VR1 is
now classified as TRPV1. Mice deficient of TRPV1 lacks
thermal pain induced by inflammation. Thus, TRPV1 is
most likely involved in the mediation of inflammatory
pain. In the present symposium, I would like to introduce
our research on TRV1, most notably, presenting evidence
for the involvement ofTRPV1 in mediating inflammatory
pain signaling pathways.

The presence of TRPV1 receptor and its apparent role in
pain suggests endogenous activator. Thus, endogenous
activators of TRPV1 were searched. In our previous report,
the hyperalgesic neural response such as c-fos expression
in the dorsal horn of the spinal cord induced by inflam-
mation is blocked by capsazepine, a CAP receptor blocker,
suggesting that an endogenous capsaicin-like substance is
produced and causes hyperalgesia by opening capsaicin-
activated channels. Because ligands bind from the intrac-
ellular side of the channel, the endogenous ligands would
likely be produced in the cell. We initially tested many
intracellular messengers on the CAP channel to determine
whether they activate the channel. We found that prod-
ucts of lipoxygenases (LO) are capable of activating the
channel. Interestingly, products of LOs are implicated in
mediating inflammatory nociception because various LO
products are produced during inflammation and cause
hyperalgesia when injected intradermally. In addition,
products of LOs often function as intracellular messengers
in neurons. Among their actions, products of LOs act
directly on K+ channels in Aplysia sensory neurons
(Piomellile et al., 1987) and mammalian cardiac muscle

In the present seminar, we present evidence that products
of LOs directly activate the CAP receptor in isolated mem-
brane patches of sensory neurons. When applied to the
bath of inside-out patches, 12-hydroperoxytetraenoic acid

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Molecular Pain 2006, 2:38

(12-HPETE) activates single-channel currents that were
sensitive to capsazepine in isolated membrane patches.
The IV curve of single-channel currents activated by 12-
HPETE is outwardly-rectifying and identical to that
obtained by CAP. The amplitude of single-channel cur-
rents activated by both 12-HPETE and CAP are not differ-
ent. Theses results indicate that the channel currents
activated by 12-HPETE are identical to those activated by
CAP. The channels activated by 12-HPETE are permeable
to various cations. LO products also activate TRPV1, the
cloned CAP receptor, expressed HEK293 cells. Products of
LOs other than 12-HPETE also activated the CAP chan-
nels. Among them, 12- and 15-HPETE, 5- and 15-(S)-
hydroxyeicosatetraenoic acids, and leukotriene B4 possess
the highest potency. Dose-response relationships reveal
that the potencies of 12-HPETE, 15-HPETE, leukotrien B4,
and 5-HETE are 8.0, 8.7, 9.2, and 11.7 gM, respectively,
showing much lower potency than CAP. Anandamide, the
endogenous ligand for cannabinoid receptors also acti-
vates the channel with half-maximal dose of 11.7 gM.
Because prostaglandins (PGs) are known to be related to
pain, various PGs are applied to the CAP receptors. PGs,
however, fail to activate the channel. Other saturated or
unsaturated fatty acids are also tested for its activation of
CAP channels. They all fail to activate the channels.

Results of our study indicate that CAP and various eicosa-
noids act on the capsaicin receptor, suggesting a structural
similarity between CAP and eicosanoids. Thus, structures
of eicosanoids and CAP in the energy-minimized state are
superimposed to compare three-dimensional structures.
Three-dimensional structures of 12-(S)-HPETE, 15-(S)-
HPETE, 5-(S)-HETE, and LTB4 are compared with that of
CAP. Interestingly, CAP in the energy-minimized state fits
well to the S-shaped 12-HPETE. In particular, the phenolic
hydroxide and amide moieties in CAP overlap precisely
with the carboxylic acid and hydroperoxide moieties in
12-HPETE, respectively. The two key regions in CAP or 12-
(S)-HPETE are known to have dipolar property that allows
hydrogen bond interactions with the CAP receptor. In
addition, the aliphatic chain region of the 12-(S)-HPETE
fits well with the alkyl chain of CAP. In contrast, 15-
HPETE, 5-HETE and LTB4, shared less structural similarity
with CAP.

Because products of LO activate the channel, it seems
obvious to ask what stimulates the LO/TRPV1 pathway in
order to cause pain. Although bradykinin (BK) is a power-
ful pain causing inflammatory mediator, but its activation
mechanism of sensory neurons is not known. Because BK
releases arachidonic acid, a key substrate for LO in sensory
neurons, we hypothesized that BK activates TRPV1 via the
PLA2/LO pathway. In order to prove the hypothesis, we
performed electrophysiological experiments, Ca2+-imag-
ing, and chemical analysis of LO products. As a result, we

observed that BK-evoked whole-cell currents recorded
from sensory neurons were significantly reduced by cap-
sazepine (CZP), a capsaicin receptor antagonist. In the
skin nerve preparation, CZP and quinacrine, a PLA2
inhibitor, and NDGA, a LO inhibitor reduced BK-induced
excitation of sensory nerves. In addition, quinacrine,
NDGA and CZP blocked BK-induced Ca2+-influx. To
examine if sensory neurons can, in fact, release the lipid
products of LO by BK, we used HPLC-coupled with radio-
isotope to detect the lipid products. As results, we con-
firmed that 12-HETE, an immediate downstream
metabolite of 12-HPETE was indeed released from sen-
sory neurons after the BK application.

In addition, we also present unequivocal evidence that
histamine, another inflammatory mediator, also uses the
PLA2/LO/TRPV1 pathway for excitation of sensory neu-
rons. Application of histamine caused influx of Ca2+,
which was blocked by co-application of capsazepine or
Ca2+-free condition. The Ca2+-influx induced by hista-
mine was blocked by application of capsazepine. Like-
wise, the Ca2+-influx induced by histamine was also
blocked by treatment of NDGA or quinacrine. Thus, these
results now suggest that histamine activates TRPV1 by
stimulation of PLA2 and LO. Because histamine is a major
pruritogenic (itch causing) substance, identification of the
histamine signaling pathway is much helpful to develop-
ing anti-pruritogenic substance to cure itch sensation in
atopic dermatitis patients.

This study demonstrates that bradykinin and histamine
excite sensory nerve endings by activating TRPV1 via pro-
duction of 12-LO metabolites of arachidonic acid by acti-
vated PLA2. This finding identifies a mechanism that
might be targeted in the development of new therapeutic
strategies for the treatment of inflammatory pain or itch.

* Ke Ren (Department of Biomedical Sciences, Univer-
sity of Maryland, Baltimore, USA) Neuronal/glial cell
interactions in CNS plasticity and persistent pain

Nerve signals arising from sites of tissue injury lead to
long-term changes in the central nervous system (CNS)
referred to as central sensitization. Ample evidence indi-
cates that central sensitization underlies mechanisms of
persistent pain after injury. The emerging literature
strongly implicates a role of neuronal/glial cell interaction
in central sensitization and hyperalgesia. Through still
unknown mechanisms, glia can be activated after injury
and release chemical mediators such as inflammatory
cytokines that modulate neuronal activity and synaptic
strength. Such glia-cytokine-neuron interactions may be
critical in the chronic pain process. We tested this hypo-
thesis in a rat model of synaptic plasticity and persistent
pain. Tissue injury was produced by injecting complete

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Molecular Pain 2006, 2:38

Freund's adjuvant (CFA), an inflammatory agent, into the
masseter muscle of the Sprague-Dawley rat. We first exam-
ined whether masseter inflammation induced glial activa-
tion in the spinal trigeminal complex (STC), the initial
relay site for trigeminal nociceptive information. The
results showed that masseter inflammation induced a
selective and time-dependent increase in glial fibrillary
acidic proteins (GFAP) levels, an indication of astroglial
activation, in the STC. We next examined whether activa-
tion of glia by masseter inflammation is accompanied by
an increase in inflammatory cytokine levels. Using West-
em blot and immunohistochemistry, an increase in IL-
Ibeta in the STC was observed after masseter inflamma-
tion. The increase in IL-lbeta was seen as early as 30 min
after inflammation and lasted for about a week. Interest-
ingly, the CFA-induced IL-lbeta selectively colocalizes
with GFAP, but not with NeuN, a neuronal marker, and
CD 1 b, a marker of activated microglia. These results sug-
gest that activated astrocytes are the source of IL-lbeta
release in the STC after masseter inflammation. To dem-
onstrate the association of inflammation-induced
cytokine release with glial activation, we tested the effect
of propentofylline, a non-selective modulator of glia, on
changes in GFAP and IL-lbeta levels after masseter
inflammation. Western blots showed that the propen-
tofylline treatment blocked the increase in GFAP and IL-
ibeta after masseter CFA. We further showed that the
increase in GFAP after masseter inflammation was
blocked by local anesthesia of the injured site, suggesting
its dependence on neuronal input. Interestingly, in a med-
ullary slice preparation, substance P, a transmitter
released from primary afferent terminals in the STC,
induced an increase in GFAP and IL-lbeta. These results
are consistent with a role of neuronal signaling in trigger-
ing CNS glial activation. Finally, we tested the hypotheses
that trigeminal glial activation and inflammatory cytokine
release affect or facilitate neuronal plasticity through
interactions with neuronal glutamate receptors. We
administered IL- receptor antagonist (ra) intrathecally via
osmotic pumps at the level of the obex. The results
showed that IL-lra significantly attenuated behavioral
hyperalgesia and blocked an increase in NMDA receptor
phosphorylation after masseter inflammation. Our find-
ings support a model of reciprocal neuron-glia interac-
tions in the development of CNS plasticity and persistent
pain. The model emphasizes activation of glia by injury-
generated neuron input, concomitant cytokine release,
and post-translational regulation of NMDA receptor sen-
sitivity through IL-1receptor signaling. The outcome of
these studies will help to identify novel targets and agents
for clinical management of persistent pain. (Supported by
NIH grants DE11964, DE15374, DA10275)

* John C Roder (Department of Medical Genetics and
Microbiology, University of Toronto, Toronto, Canada)

- Forward and reverse genetic screens in the mouse for
mutants impaired in learning and memory

Learning and memory in the mouse is a quantitative trait
and genes account for 71% of the variance between
strains. Our goal here is to identify new genes that contrib-
ute to learning and memory. We will employ a forward
genetic screen using a chemical mutagen (ENU). A total of
2500 ENU mice were pre-screened for normal develop-
ment. Of these, 10 showed deficits in context-dependent
fear conditioning (< 2 sd from the mean), but normal cue-
dependent freezing. A smaller screen was done on 100
mice. 2 showed deficits in performance on the hidden
platform but normal performance on the visible platform
(control). All these presumed mutants showed low herit-
ability and penetrance and could not be mapped to chro-
mosomal positions. At this point we revised our screen.

A number of strains (n = 10) were compared in the water
maze and the one showing optimal performance (129
S61SVE-v Tac) was chosen for ENU mutagenesis. In addi-
tion, we changed the screen to a much more difficult task
and one that relied on a different sensory modality
(sound) in trace conditioning.

Upon screening 450 mice in trace only, one was obtained
that showed no freezing. This mutant showed robust
inheritance and penetrance and we are in the process of
fine mapping, positional cloning and sequencing of the
antifreeze locus. Verification of candidate genes will be
carried out by BAC rescue of the mutant phenotype with
the wildtype gene. Alternatively, the creation of the same
mutant phenotype in wildtype mice by mutating the wild-
type locus in ES cells.

We will carry out extensive neurobehavioural assays to
determine if the learning and memory deficits are
restricted to the hippocampus or are found in other brain
regions as well (i.e. pre-frontal cortex, cerebellum, nucleus
accumbens, brain stem, amygdala, striatum). Learning
and memory mutants will be tested for their ability to
form cognitive spatial maps in the hippocampus in vivo.
Neuroanatomical studies will assess if development per-
turbation underlie these deficits. Gene expression and
proteomic studies will identify where the gene is
expressed and the biochemical pathway underlying its
action. Modifier screens will be carried out to elucidate
exciting new genetic pathways. The mutant genes we iden-
tify will be models for human genetic diseases that involve
impairments in learning and memory. In these cases, the
mutant mice will provide test beds for pre-clinical tests of
cognitive enhancers in patients. In addition, they will sug-
gest new targets for drug development.

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Molecular Pain 2006, 2:38

* Michael W Salter (Department of Physiology, Univer-
sity of Toronto, Toronto, Canada) Ins and outs of SRC
regulation of NMDA receptors and synaptic plasticity

Regulation of postsynaptic glutamate receptors is one of
the principal mechanisms for producing alterations of
synaptic efficacy in the CNS. A growing body of evidence
indicates that at glutamatergic synapses NMDA receptors
are upregulated by Src family tyrosine kinases which are
opposed by the action of tyrosine phosphatases, one of
which has been identified as STEP. Src itself is expressed
nearly ubiquitously in higher organisms with the highest
levels of expression found in the CNS. Src represents a
point through which multiple signaling cascades from, for
example G-protein-coupled receptors, Eph receptors and
integrins, converge to upregulate NMDA receptor activity.
The upregulation of NMDARs by activation of Src partici-
pates in the induction of long-term potentiation of synap-
tic transmission in the hippocampus and in the spinal
cord dorsal horn. We have determined that Src is
anchored within the NMDA receptor complex by the pro-
tein ND2. Recently, we have found that interfering with
the ND2-Src interaction in vivo prevents behavioral pain
hypersensitivity. Thus, multiple mechanisms control Src
in the NMDA receptor complex and disrupting Src-medi-
ated enhancement of NMDA receptor function affects
pathological plasticity in the CNS.

* Weihong Song (Department of Psychiatry, University
of British Columbia, Vancouver, Canada) Hypoxia
facilitates Alzheimer's disease pathogenesis

The molecular mechanism underlying the pathogenesis of
majority of sporadic Alzheimer's disease (AD) cases is
unknown. A history of stroke was found to be associated
with development of some AD cases, especially in the
presence of vascular risk factors. A reduced cerebral per-
fusion is a common vascular component among AD risk
factors. Hypoxia is a direct consequence of hypoper-
fusion. We identified a functional hypoxia responsive ele-
ment (HRE) in BACE1 promoter. Hypoxia increased APP
CTFB production by increasing BACE1 gene transcription
and expression in vitro and in vivo. This paper showed that
hypoxia facilitated AD pathogenesis. Under hypoxic con-
dition APP23 mice, Swedish mutant APP transgenic mice,
developed more neuritic plaques than normoxic mice. We
found that hypoxia deteriorated the memory impairment
in APP23 mice. Our results demonstrate that hypoxia
facilitates AD pathogenesis and interventions that
improve cerebral perfusion might benefit AD patients.

* Shuzo Sugita (Department of Physiology, University
of Toronto, Toronto, Canada) Molecular mechanism
of GTP-dependent exocytosis

Many secretary cells utilize a GTP-dependent pathway to
trigger exocytotic secretion. However, little is currently
known about the mechanism by which this may occur. In
the present study we attempted to identify the key signal-
ing pathway that mediates GTP-dependent exocytosis.
Incubation of permeabilized PC12 cells with soluble RalA
GTPase strongly inhibited GTP-dependent exocytosis. A
Ral-binding fragment from Sec5, a component of the exo-
cyst complex, showed a similar inhibition. Point muta-
tions in both RalA (RalAE38R) and the Sec5 (Sec5T11A)
fragment which abolish the RalA-Sec5 interaction also
abolished the inhibition of GTP-dependent exocytosis. In
contrast the RalA and the Sec5 fragment showed no inhi-
bition of Ca2+-dependent exocytosis, but cleavage of a
SNARE (soluble-N-ethylmaleimide-sensitive factor
attachment protein receptor) protein by Botulinum neu-
rotoxin blocked both GTP- and Ca2+-dependent exocyto-
sis. In stable RalA and RalB double knockdown cells, GTP-
dependent exocytosis was severely reduced and was
restored upon reintroducing expression of RalA or RalB by
transfection. However, Ca2+-dependent exocytosis
remained unchanged in the double-knockdown cells. Our
results indicate that GTP- and Ca2+-dependent exocytosis
use different sensors and effectors for triggering exocytosis
while their final fusion steps are both SNARE-dependent.
They also suggest that endogenous RalA and RalB func-
tion specifically as GTP sensors for the GTP-dependent

* Shao-Jun Tang (Department of Neurobiology and
Behavior, University of California, Irvine, USA) Regu-
lation of Activity-Dependent Protein Synthesis in Den-

Protein synthesis in dendrites is essential for long-lasting
synaptic plasticity, but little is known about how synaptic
activity is coupled to mRNA translation. Using hippocam-
pal neuron cultures and slices, we have investigated the
role of glutamate receptors and mTOR signaling in con-
trol of dendritic protein synthesis. We find: 1) Specific
antagonists of NMDA, AMPA and metabotropic gluta-
mate receptors abolish glutamate-induced dendritic pro-
tein synthesis, whereas agonists of NMDA and
metabotropic but not AMPA glutamate receptors activate
protein synthesis in dendrites; 2) Inhibition of mTOR sig-
naling, as well as its upstream activators, PI3K and AKT,
block NMDA receptor-dependent dendritic protein syn-
thesis. Conversely, activation of mTOR signaling induces
dendritic protein synthesis; and 3) Dendritic protein syn-
thesis activated by tetanus-mediated LTP induction in hip-
pocampal slices requires NMDA receptors and mTOR
signaling. These results suggest critical role of the NMDA
receptor-mTOR signaling pathway in regulating protein
synthesis in dendrites of hippocampal neurons.

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Molecular Pain 2006, 2:38

* Yuanxiang Tao (Department of Anesthesiology and
Critical Care Medicine, Johns Hopkins University, Bal-
timore, USA) Are the PDZ domains at excitatory syn-
apses potential molecular targets for prevention and
treatment of chronic pain?

The PDZ (Postsynaptic density 95, Discs large, and
Zonula occludens-1) domains are ubiquitous protein
interaction modules often found among multi-protein
signaling complexes at excitatory synapses. In the mam-
malian central nervous system, C-terminal motifs of N-
methyl-d-aspartate (NMDA) receptor subunits NR2A and
NR2B bind to the first and second PDZ domains of post-
synaptic density (PSD)-95, PSD-93, and synaptic-associ-
ated protein (SAP)102, whereas C-terminal motifs of a-
amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid
(AMPA) receptor subunit GluR2 interacts with the PDZ
domain of protein interacting with C-kinase 1 (PICK1)
and glutamate receptor interacting protein (GRIP). These
PDZ-containing proteins not only are involved in synaptic
trafficking of NMDA receptors and AMPA receptors but
also couple the receptors to intracellular proteins and sig-
naling enzymes, such as neuronal nitric oxide synthase
(nNOS) and protein kinase C (PKC). Recent preclinical
research shows that PSD-93, PSD-95, and PICK1 are
highly expressed in the dorsal horn of the spinal cord.
Immunocytochemical studies demonstrate that their
immunoreactivities occur at a higher density in the super-
ficial laminae and at a lower density in other laminae of
the spinal dorsal horn. Spinal PSD-93 or PSD-95 deletion
prevents NMDA receptor-dependent chronic pain from
spinal nerve injury or injection of complete Freund's adju-
vant (CFA) without affecting nociceptive responsiveness
to acute pain. In addition, the disruption of the PDZ
domain-mediated protein interaction between GluR2 and
PICK1 in the spinal cord of rats or the knockout of PICK1
in mice has recently been shown to produce antinocicep-
tive effects in AMPA receptor-dependent chronic pain
caused by peripheral nerve injury and CFA, with preserva-
tion of acute pain transmission. Further studies have dem-
onstrated that PSD-93 or PSD-95 deletion may alter the
synaptic NMDA receptor expression and function in spi-
nal cord neurons, which, in turn, may result in impaired
NMDA receptor-dependent chronic pain. However, the
underlying mechanism by which PICK1 lead to antinoci-
ception in chronic pain states is unclear. Our preliminary
work indicates that CFA-induced chronic pain might
increase time-dependent PKC phosphorylation of GluR2
Ser880, disrupt interaction of GluR2 with GRIP (but not
with PICK1), and lead to PKC-dependent internalization
of GluR2 (but not of GluR1) in the spinal cord neurons.
GluR2 internalization might facilitate Ca2+ permeability
and increase AMPAR function and neuronal activity,
which may contribute to spinal central sensitization asso-
ciated with chronic pain states. PICK1 deletion might

reduce PKC phosphorylation of GluR2 Ser880 by block-
ing the recruitment of PKC to synaptic GluR2 and
decrease PKC-dependent internalization of GluR2 in spi-
nal cord neurons, which, in turn, might result in blunted
AMPA receptor-dependent central sensitization in chronic
pain. Therefore, it is very likely that PDZ domains at exci-
tatory synapses may be new molecular targets for preven-
tion and treatment of chronic pain.

* Yu Tian Wang (Brain Research Center, University of
British Columbia, Vancouver, Canada) Synaptic plas-
ticity in learning and memory

Synaptic plasticity (i.e. a dynamic change in the strength
of synaptic transmission between neurons), such as long-
term potentiation (LTP) and depression (LTD) observed
at the glutamatergic synapses of the CA1 region of the hip-
pocampus, has long been proposed as a primary cellular
mechanism for learning and memory. However, evidence
for a definitive role of either LTP or LTD in learning and
memory remains missing due to the lack of a specific
inhibitor for LTP or LTD. Evidence accumulated in recent
years strongly suggests that AMPA subtype glutamate
receptors (AMPARs) are continuously cycling between the
plasma membrane and intracellular compartments via
vesicle-mediated plasma membrane insertion and endo-
cytosis, and that facilitated AMPAR insertion and endocy-
tosis at postsynaptic membranes contributes to the
expression of LTP and LTD, respectively. Using a combi-
nation of recombinant receptor expression systems and
hippocampal brain slice preparations, we were able to
demonstrate that facilitated endocytosis of postsynaptic
AMPARs during LTD is AMPAR GluR2 subunit-specific.
These studies have lead us to develop a GluR2-derived
interference peptide that, when delivered into neurons in
the brain, can specifically block the expression of LTD
without affecting normal basal synaptic transmission in
many regions of the brain. Using the membrane-per-
meant form of the GluR2 peptide as a specific inhibitor of
LTD, we were able to probe the role of LTD in freely mov-
ing rats with unprecedented specificity, and thereby pro-
vide evidence for the involvement of LTD in a number of
learning and memory-related behaviours. Our work not
only provides the first evidence for a definitive role of LTD
in learning and memory, but also demonstrates the utility
of peptides that disrupt AMPAR trafficking, the final step
in the expression of synaptic plasticity, as tools to examine
the critical role of LTD and/or LTP in specific aspects of
learning and memory in conscious animals.

* Newton Woo (NICHD, NIH, Bethesda, USA) Regu-
lation of Bi-directional Plasticity by BDNF

Initially characterized for its role in neuronal survival and
differentiation, Brain Derived Neurotrophic Factor

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Molecular Pain 2006, 2:38

(BDNF) has emerged as a key regulator of synaptic plastic-
ity, which is a persistent change in synaptic strength
thought to underlie many cognitive functions. A salient
characteristic of this ubiquitously expressed neurotrophin
is that expression of BDNF is activity dependent, which
has profound implications in development and neuronal
plasticity. BDNF is synthesized as a precursor (proBDNF)
that can undergo proteolytic cleavage to yield mature
BDNF (mBDNF). Initially, the biological actions elicited
by neurotrophins, including BDNF, were thought to only
arise from the processed mature form. However, recent
groundbreaking studies have demonstrated distinct bio-
logical roles for several proneurotrophins and their
mature form via distinct receptor/signaling cascades. This
highlights the importance of the conversion of pro- to
mature protein as a key regulatory step in neurotrophin
actions. However, whether this proteolytic cleavage plays
a role in synaptic plasticity has not been previously
addressed. Here, I present evidence that such a conversion
process from pro- to mature BDNF is important for one
long-lasting form of synaptic plasticity, namely late-phase
LTP (L-LTP). Application of strong theta-burst stimulation
(TBS) induces L-LTP that is protein synthesis dependent.
In BDNF +/- mice, L-LTP is significantly impaired after
TBS simulation. However, L-LTP can be rescued in BDNF
+/- mice when hippocampal slices were preincubated with
mBDNF but not proBDNF. Subsequent experiments iden-
tified the tPA/plasminogen system plays a critical role for
both BDNF processing and L-LTP expression in the mouse
hippocampus. To investigate the location of this conver-
sion process, we performed several additional experi-
ments using cleavage specific antibodies. It was
discovered that in cultured hippocampal neurons, low fre-
quency stimulation triggered proBDNF secretion, whereas
high frequency stimulation induced the expression of
mBDNF. Strikingly, tPA secretion only occurred after high
frequency stimulation. Moreover surface staining of
mBDNF was greatly enhanced upon depolarization. These
results suggest that neuronal activity regulates the ratio of
extracellular pro- to mature BDNF via tPA secretion.
Finally, I present data that proBDNF facilitates hippocam-
pal long-term depression (LTD). This facilitation of
NMDAR LTD is dependent on the p75 neurotrophin
receptor (p75NTR). Mice that lack p75TR exhibit a selective
impairment in the NMDA-dependent form of long-term
depression (LTD), but display normal expression of other
hippocampal forms of synaptic plasticity. This selective
deficit may be the result of a significant reduction in
NR2B, a NMDA receptor subunit uniquely involved in
LTD. Activation of p75TRby proBDNF enhanced hippoc-
ampal LTD. Our results challenge the classic view that the
processed neurotrophins is the only functional form of
neurotrophins to elicit biological actions and that an
unexpected function of p75>TR is to regulate the expres-
sion of hippocampal synaptic depression. Taken together,

these results suggest a universal "Yin-Yang" model where
pro- and mature- BDNF play diametrically opposite roles
in synaptic plasticity.

* Melanie A Woodin (Department of Cell and Systems
Biology, University of Toronto, Toronto, Canada) -
Bidirectional spike-timing dependent plasticity of
inhibitory transmission in the hippocampus

The mammalian hippocampus, owing to its crucial role in
memory, has been the primary focus of research into syn-
aptic plasticity. Most studies have examined plasticity at
excitatory (glutamatergic) synapses, despite the fact that
neuronal output is not determined by the level of excita-
tory transmission alone, but by the levels of coincident
excitatory and inhibitory transmission. In this study, we
examined spike-timing dependent plasticity of GABAA
receptor mediated inhibitory transmission in area CA1 of
hippocampal slices from mature rats (6-8 weeks).
Because the amplitude and reversal potential of GABAR
currents are largely determined by intracellular chloride
concentration, we first determined the GABAR reversal
potential under conditions of intact intracellular chloride
using the permeating agent gramicidin. Surprisingly, we
found that GABAR reversal potential was ~12 mV hyper-
polarized compared to the reversal potential in a previous
study of STDP of GABAR mediated transmission in P12-
19 slices, as well as to our own recordings from P12-19
slices. We then performed a series of whole-cell recordings
to determine the intacellular chloride concentration nec-
essary to reproduce the GABAAR reversal potential meas-
ured with gramicidin. This allowed us to employ long-
term, stable whole-cell recording to investigate whether a
spike-timing protocol could induce changes in GABAAR
reversal potential. Surprisingly, pairing of presynaptic
stimulation with postsynaptic spiking led to bidirectional
changes in the reversal potential, with the direction of
change being dependent on the interval between pre- and
post stimulation. When the postsynaptic neuron was
made to fire bursts of action potentials 5 ms after presyn-
aptic stimulation (correlated), at 5 Hz for 90 seconds, a
depolarization of the reversal potential was seen. How-
ever, when the interval was lengthened to 100 ms (uncor-
related), a hyperpolarization of the reversal was seen. Due
to the interplay between excitatory and inhibitory trans-
mission, we suggest that this form of GABAergic plasticity
may contribute to the enhancement of excitatory trans-
mission under certain conditions.

* Zhen Yan (Department of Physiology and Biophysics,
State University of New York at Buffalo, Buffalo, USA)
- Interactions between Acetylcholine, Amyloid and Ion
Channels in Alzheimer's Disease

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Molecular Pain 2006, 2:38

It has been well recognized that one prominent feature of
Alzheimer's disease (AD) is the accumulation of b-amy-
loid (Ab), a major component of senile plaques. Another
fundamental feature of AD is the severe degeneration of
basal forebrain (BF) cholinergic neurons and deficient
cholinergic functions in prefrontal cortex (PFC), a brain
region implicated in high-level cognitive processes. We
have found that cholinergic inputs from BF, by activating
M1 muscarinic receptors in PFC pyramidal neurons, regu-
late the GABAA receptor channel, a key player in working
memory, through a PKC/Src-dependent mechanism. The
M1 regulation of GABA transmission in PFC is impaired
in the APP transgenic model of AD, due to the Ab interfer-
ence with M1 activation of PKC. On the other hand, gluta-
mate inputs from PFC, by activating Group III
metabotropic glutamate receptors (mGluRIII) in BF neu-
rons, suppresses NMDAR currents through an actin-
dependent mechanism. Ab selectively disrupts mGluRIII
regulation of NMDAR channels in BF cholinergic neu-
rons, which may due to their sensitivity to Ab-induced
cytoskeleton disintegration. Thus, our results have pro-
vided a potential mechanism for the synaptic failure of
PFC pyramidal neurons and the selective degeneration of
BF cholinergic neurons at the early stage of AD.

* Megumu Yoshimura (Department of Basic Medicine,
Kyushu University, Kyushu, Japan) Synaptic mecha-
nisms of acupuncture in the spinal dorsal horn revealed
by in vivo patch-clamp recordings

According to Chinese literatures, more than 300 acu-
points have been described. Stimulation of each point
elicits certain analgesia in the corresponding area. Physio-
logical examinations have been made to unveil the mech-
anisms of the analgesic action of acupuncture, however,
clear results have not been provided, because of difficulty
in how to approach the changes of nociceptive transmis-
sion in CNS. One of promising approaches will be an in
vivo patch-clamp recording from spinal dorsal horn neu-
rons to see what is happening during acupuncture. Thus,
we applied the in vivo patch-clamp recordings from sub-
stantia gelatinosa neurons that receive noxious inputs and
observed a change in excitatory and inhibitory synaptic
currents occurring spontaneously or evoked by stimulation
of the skin in the receptive field. To enhance the nocicep-
tive inputs from periphery, we used CFA induced inflam-
matory rats injected right hind paw. In this chronic pain
model, spontaneous EPSCs with higher magnitude were
observed in the majority of SG neurons. Application of
acupuncture to the contralateral ST36 near the knee joint
did not affect the spontaneous EPSCs. However, large
amplitude of spontaneous IPSCs were elicited with the
frequency of 2 to 10 Hz. Next, we tested the cell firing in
the SG by stimulation of the skin with toothed forceps
during the acupuncture. The skin-evoked spike firing was

effectively inhibited reversibly by the acupuncture. In our
previous slice experiments, noradrenaline and serotonin
increased spontaneous IPSCs with large ampitude. Other
possible candidates responsible for the depression of
nociceptive inputs to the SG, such as dopamine, enkepha-
lin, other opioids, substance P, CGRP did not increase the
frequency and amplitude of spontaneous IPSCs.

* Ming Xu (Department of Anesthesia and Critical Care,
University of Chicago, Chicago, USA) Molecular
Mechanisms of neuronal plasticity induced by drugs of

Drug addiction is a brain disease that is characterized by
the compulsive seeking and taking of a drug despite
known adverse consequences. Drug addiction is also
long-lasting with a high propensity to relapse. The brain
dopaminergic system is a key neural substrate for mediat-
ing the actions of abused drugs. The development of drug
addiction is thought to involve coordinated temporal and
spatial actions of specific dopamine receptors, signaling
molecules, and target molecules that change synaptic
reorganizations in the brain. To dissect mechanisms
underlying drug-induced neuroadaptations, we have
made and analyzed D 1 receptor mutant mice. We found
that the D1 receptor mediates the locomotor-stimulating
and rewarding effects of cocaine. The D1 receptor also
mediates cocaine-induced changes in neuronal dendritic
remodeling, ERK and CREB signaling, chromatin remod-
eling, and gene expression including c-fos and AP- 1-regu-
lated target genes. These results suggest that the D1
receptor is a major cell surface mediator for drug-induced
behaviors and neuroadaptations, and that c-fos-regulated
gene expression may contribute to the persistent nature of
drug-induced behaviors. To investigate intracellular
mechanisms of cocaine-induced persistent changes
within D1 receptor-expressing neurons, we made D1
receptor neuron-specific c-fos mutant mice. We found that
c-Fos contributes to the development and extinction of
cocaine-induced conditioned place preference and behav-
ioral sensitization, changes in dendritic reorganization,
and regulation of immediate early genes and the expres-
sion of two classes of target genes that are involved in neu-
rotransmission and neuronal connections. Noticeably,
mutations of the D 1 receptor gene and c-fos share several
common consequences after repeated cocaine injections.
Together, these findings suggest that the dopamine D1
receptor and c-Fos are a key receptor signaling system that
contributes to persistent neuroadaptations to cocaine.

* Zao C Xu (Department of Anatomy and Cell Biology,
Indiana University School of Medicine, Indianapolis,
USA) Synaptic plasticity in pathological conditions

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Molecular Pain 2006, 2:38

Synaptic plasticity occurs during development and partic-
ipates in physiological functions in adulthood during
learning and memory. It has also been shown in patho-
logical conditions such as epilepsy. To investigate the syn-
aptic plasticity in neurodegenerative disorders and the
underlying mechanisms, synaptic transmission and mor-
phological changes were studied in neurotransplantations
after excitotoxic lesion and in neurons after transient cer-
ebral ischemia.

For transplantation studies, striatal primordium were col-
lected from 16 d embryos and implanted into the striatum
of adult Sprague-Dawley rats two days after kainic acid
lesion. Intracellular recording in vivo and anterograde
tracing experiments were performed 2-6 months after the
transplantation. For ischemia studies, transient global
ischemia was induced in adult Wistar rats. Electrophysio-
logical recording and morphometry analysis ofintracellu-
larly stained neurons were performed at different intervals
after ischemia.

Spontaneous synaptic activities were greatly reduced in
striatal grafts. Cortical or thalamic stimuli elicited mono-
synaptic excitatory postsynaptic potentials (EPSPs) from
neurons in the graft. A late postsynaptic potential (L-PSP)
was evoked from many graft neurons (17/27) in addition
to the initial EPSPs. Bursting action potentials were gener-
ated from the L-PSPs. Light and electron microscopic stud-
ies showed that the number of cortical and thalamic
afferent fibers significantly reduced in the grafts. Some of
these fibers formed dense clusters of terminals making
multiple synapses on individual spines and dendrites. L-
PSPs also could be evoked from neurons in the striatum
and hippocampus following cerebral ischemia. Further-
more, the initial EPSPs were potentiated in ischemia-vul-
nerable neurons (spiny neurons in the striatum and
CAlneurons in the hippocampus) but depressed or
unchanged in ischemia-resistant neurons (large aspiny
neurons in the striatum and CA3 neurons in the hippoc-
ampus) after ischemia. Quantitative analysis of 3-D
reconstructed CA1 pyramidal neurons indicated that the
total dendritic length in apical dendrites was significantly
increased at 24 h after ischemia but remained about the
same in basal dendrites. Such increase was due to the den-
dritic sprouting rather than dendritic extension, which
occurred mainly in the middle segment of the apical den-

These results demonstrate that the synaptic plasticity
changes also occur in acute neurodegenerative disorders.
The plasticity changes in striatal grafts might be the com-
pensatory responses, whereas those in ischemic neurons
might be associated with the selective neuronal damage
after ischemic insults.

* Xia Zhang (Department of Psychiatry, University of
Saskatchewan, Saskatoon, Canada) Cannabinoid
addiction and cannabinoid medicine

A. Suppression of cannabinoid rewarding effects and can-
nabinoid withdrawal syndrome respectively by the inter-
fering peptide Tat-3L4F and lithium

Cannabinoids or marijuana is the most commonly used
illicit drug in developed countries. The lifetime prevalence
of marijuana dependence is the highest of all illicit drugs
in the USA, but there is no effective medication available
for treating marijuana addiction. Our recent two studies
show potential strategies for treating marijuana addiction
in humans. In the first study we found a physical interac-
tion of the enzyme PTEN with a region in the third intra-
cellular loop (3L4F) of 5-HT2C receptor (5-HT2cR) in cell
cultures. PTEN limits agonist-induced phosphorylation of
5-HT2cR through its protein phosphatase activity. We
then found the probable existence of PTEN:5-HT2cR com-
plexes in putative dopaminergic neurons in the rat ventral
tegmental area (VTA), a brain region in which virtually all
abused drugs exert rewarding effects by activating its
dopamine neurons. We next synthesized the interfering
peptide Tat-3L4F, which is able to disrupt PTEN coupling
with 5-HT2cR. Tat-3L4F or the 5-HT2cR agonist
Ro600175 suppressed the increased firing rate of VTA
dopaminergic neurons induced by delta9-tetrahydrocan-
nabinol (THC), the psychoactive ingredient of marijuana.
Using behavioral tests, we observed that Tat-3L4F or
Ro600175 blocks conditioned place preference of THC,
and that Ro600175, but not Tat-3L4F, produces anxio-
genic effects, penile erection, hypophagia and motor func-
tional suppression. These results suggest a potential
strategy for treating cannabinoid addiction with the Tat-
3L4F peptide. In the second study we demonstrate that
lithium treatment prevented the cannabinoid withdrawal
syndrome (CWS) in rats, which was accompanied by
expression of the cellular activation marker Fos in oxy-
tocin-immunoreactive neurons and a significant increase
in oxytocin mRNA expression in the hypothalamic par-
aventricular and supraoptic nuclei. Lithium also signifi-
cantly increased blood oxytocin levels. We suggest that the
effects of lithium against the CWS are mediated by oxytoc-
inergic neuronal activation and subsequent release and
action of oxytocin within the CNS. This hypothesis is sup-
ported by further findings that the effects of lithium
against the CWS were antagonized by an oxytocin antago-
nist and mimicked by oxytocin. These results led us to
conduct a small-scale, pilot clinical study showing posi-
tive therapeutic effects of lithium against the CWS in
patients with pure cannabinoid addiction.

B. Promotion of hippocampal neurogenesis and suppres-
sion of anxiety and depression by cannabinoids. The adult

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Molecular Pain 2006, 2:38

hippocampus contains neural stem/progenitor cells (NS/
PCs) capable of generating new neurons, i.e., neurogene-
sis. Most drugs of abuse examined to date decrease adult
hippocampal neurogenesis, but the effects of cannabi-
noids remain unknown. We show that both embryonic
and adult rat hippocampal NS/PCs are immunoreactive
for CB1 cannabinoid receptors. We then found that both
the synthetic cannabinoid HU210 and an endogenous
cannabinoid promote proliferation, but not differentia-
tion, of cultured embryonic hippocampal NS/PCs likely
via a sequential activation of CB1 receptors, Gi/o proteins,
and ERK signaling. Chronic, but not acute, HU210 treat-
ment promoted adult hippocampal neurogenesis and
exerted anxiolytic- and antidepressant-like effects. X-irra-
diation of the hippocampus blocked both the neurogenic
and behavioral effects of chronic HU210 treatment, sug-
gesting that chronic HU210 treatment produces anxio-
lytic- and antidepressant-like effects likely via promotion
of hippocampal neurogenesis.

* Mei Zhen (Department of Medical Genetics and
Microbiology, University of Toronto, Toronto, Canada)
- SAD kinase regulates neuronal polarity and synapse

Using C. elegans GABAergic neurons as a model system,
we identified a Ser/Thr kinase SAD-1 as a key player in
establishing axon/dendrite polarity and synaptic struc-
tures. In C. elegans the loss of the SAD-1 function leads to
the accumulation of synaptic vesicles at dendritic regions
of neurites, furthermore synaptic vesicles are loosely clus-
tered at chemical synapses. Using genetic and biochemical
approaches, we determined two separate genetic path-
ways through which SAD-1 kinase functions: During early
differentiation of neurons, SAD-1 physically interacts
with a scaffolding protein Neurabin to restrict the axonal
fate of the developing neurites. After the establishment of
axon and dendrites, SAD-1, restricted at presynaptic
region by several presynaptic channels, negatively con-
trols the incorporation of active zone proteins at chemical
synapses. We are further delineating the activator and
downstream effectors of the SAD kinase.

* Min Zhuo (Department of Physiology, University of
Toronto, Toronto, Canada) Cortical potentiation and
its roles in persistent pain and fear

Neuronal synapses in the central nervous systems are plas-
tic, and can undergo long-term changes throughout life.
Studies of molecular and cellular mechanisms of such
changes not only provide important insight into how we
learn and store new knowledge in our brains, but also
reveal the mechanisms of pathological changes occurring
following a noxious stimulus such as pain and fear. Using
integrative approaches including genetic, pharmacologi-

cal, electrophysiological and behavioral studies, we
explore the synaptic mechanisms for LTP and LTD in the
cingulate and prefrontal cortex of adult mice. We found
that activation of postsynaptic NMDA receptor is required
for the induction of synaptic LTP. The expression of cingu-
late LTP is likely mediated by postsynaptic AMPA recep-
tors, while presynaptic form of paired-pulse facilitation
remained unchanged during synaptic potentiation. Acti-
vation of calcium-calmodulin stimulated adenylyl cyclase
AC1 is required for the induction of LTP. Similar to the
hippocampus, NMDA NR2A subtype receptor is required
for the induction of LTP. NMDA NR2B receptors, how-
ever, also contribute to synaptic potentiation. Genetic
reduction of NR2B expression or pharmacological inhibi-
tion of NR2B receptor by selective antagonists reduced
behavioral contexual fear memory. The possible contribu-
tion of the ACC to the formation of fear memory is its role
in pain perception. Supporting this hypothesis, inhibition
of NMDA NR2NB receptors in the ACC inhibited behav-
ioral sensitization to non-noxious stimuli. Our results
provide strong evidence that synaptic potentiation within
the cingulate/prefrontal cortex play important roles phys-
iological and pathological responses to noxious sensory
stimuli and injury, including emotional fear and persist-
ent pain.

Competing interests
The authors) declare that they have no competing inter-

Authors' contributions
Each author provided abstract for the 1st International
Conference on Synapse, Memory, Drug Addiction and
Pain, as indicated in the manuscript. MZ collected and
organized abstracts for publishing. All authors read and
approved the final manuscript.

MZ is supported by grants from NINDS NS42722, the Canadian Institutes
of Health Research, the EJLB-CIHR Michael Smith Chair in Neurosciences
and Mental Health, and the Canada Research Chair.

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