Marina Picciotto

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STUDIES ON THE MOLECULAR BASIS OF NICOTINE
ADDICTION
Marina Picciotto Depts. of Psychiatry,
Neurobiology Pharmacology Yale University
School of Medicine
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The Waletzky Family
Jacob Waletzky
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My Mentors
P Greengard
J-P Changeux
R Scheller
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NIDA
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Current lab members Yuki Asaka Amine
Bahi Christian Brabant Emily Einstein Nadia
Gavrilova Christopher Heath
Past lab members Nii Addy Bob Beech Darlene
Brunzell Barbara Caldarone Ali Harrist Jessica
Hawes Sarah King Roopa Narasimhaiah Reba
Rabenstein Oli Somenzi Tanya Stevens Rebecca
Steiner Nataly Uboha Vanna Zachariou
Yonwoo Jung Helen Kamens Jérémie Lavaur Diane
Lendroth Yann Mineur
Collaborators
Steve Buka J-P Changeux Clement Lena Al
Collins Sharon Grady Michael Marks
Ron Duman Sam Newton Reiko
Fitzsimonds Tony George Stephanie
OMalley Julie Staley Michele Zoli
Funding
NIDA NIMH
TTURC NARSAD
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Smoking is still the leading cause of death in
the developed world
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The majority of smokers start as adolescents
Maternal and adolescent smoking have long-lasting
effects on behavior (Jacobsen). Nicotine can
accelarate maturation of GABA neurons (Berg) and
potentiate synaptic plasticity during critical
periods of development (Metherate, King).
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Structure of nicotinic ACh receptors
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Nicotinic subunit in situ - VTA
Zoli, unpublished
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Nicotine regulation of the DA system
ACh
- nicotine
- dopamine
DA
GLU
- a7 subunit containing nAChR
- b2 subunit containing nAChR
DA
DA
DA
DA
GABA
Nucleus accumbens
Ventral tegmental area
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WT
KO
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Nicotine does not stimulate dopamine release in
b2-/- mice...
Nicotine 10 mM
Picciotto et al, Nature, 1998
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and is not reinforcing
3000
wt-sac
2500
wt-nic
ko-sac
2000
ko-nic
mean beam breaks/hr
1500
1000
500
0
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2PM
4
6
8
10
12
2AM
4
6
8
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Time of day
Picciotto et al, Nature, 1998
King et al, Neuropharm. 2004
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WT
KO
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Constitutive b2 subunit knockout results in
hypersensitive passive avoidance learning
.
Time to enter dark (sec)
Picciotto et al, Nature, 1995
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• Questions to be answered
• Where in the brain is this happening?
• When during development are nAChRs necessary for
  this effect?
• What are the effects of nicotine on this behavior?

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Inducible region specific expression
Temporal-control of gene expression
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Region-specific gene expression
?2 /-
?2 -/-
b2 tr(CT)
b2 tr(VN)
b2 tr(VTA)
b2 tr(FB) (CamKII-tTA)
King et al, J. Neurosci., 2003
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wildtype
transgenic
b2 knockout
Nicotine binding
cortex
Rubidium efflux
in situ hybridization
thalamus
King et al, J. Neurosci., 2003
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Corticothalamic expression of b2 nAChRs rescues
adult passive avoidance
King et al, J. Neurosci., 2003
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Temporally-controlled gene expression
King et al, J. Neurosci., 2003
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Passive avoidance behavior depends on presence of
b2 nAChRs during development
King et al, J. Neurosci., 2003
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The b2 nAChR transgene is expressed in
corticothalamic efferents after P7
Sarah King
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Synaptic maturation in cortex and thalamus occurs
in the second postnatal week (rodent) or 3rd
trimester (human). Chronic nicotine treatment
during this critical period -Enhances NMDA
receptor-mediated transmission in neocortex of
rats (Aramakis and Metherate 1998). -Increases
NR2A mRNA in auditory cortex layer 6 and
decreases NR2B in medial geniculate (auditory
thalamus) (Hsieh et al. 2002).
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Dams 200 ug/ml nicotine in drinking water -
Offspring weaned on water (3 - 4 weeks),
tested as adults (3 - 5 months).
Nicotine during development results in
hypersensitive passive avoidance in adulthood
King et al, submitted, 2008
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Nicotine affects PA learning when administered
only posnatally
320
train

280
test

240
200
160
120
80
40
0
Sac-Sac
Sac-Nic
Nic-Sac
Nic-Nic
birth
weaning
conception
Day -19.5
Day 0
Day 21
nicotine
Saccharin
King et al, submitted, 2008
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Developmental nicotine exposure in humans is
linked to

• ADHD
• Conduct disorder
• Altered auditory processing
• Lower IQ
• Increased likelihood of smoking
• (Ernst et al., 2001 Wakschlag et al., 2002)

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Developmental smoke exposure increases white
matter maturation in internal capsule
Jacobsen et al, J Neurosci, 2007
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What we think is happening
X
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Summary

• Both perinatal nicotine exposure and b2 nACHR
  KO result in hypersensitive passive avoidance in
  adulthood
• Expression in corticothalamic efferents rescues
  this defect in KO mice
• nAChR signaling may be critical for maturation
  of corticothalamic glutamate synapses