[Abstract Title]. - Society for Neuroscience

of Menk levels in the globus pallidus due to the feedback importance of the D-2 receptordominated
Menk pathway in the extrapyramidal system. Male Sprague-Dawley rats received
multiple administrations of (+/-) nicotine totaling 4.0 mg/kg/day (0.8 mg/kg, i.p.: 5 X 2h
intervals) in the presence or absence of selective DA receptor antagonists (D-1, SCH23390; D-2,
eticlopride) or a non-selective nicotinic receptor antagonist (mecamylamine; 3.0 mg/kg, s.c.) and
were sacrificed 18 h after treatment. The nicotine injections significantly reduced pallidal Menk
levels, an effect that was blocked by pretreatment with either the D-2 or nicotinic, but not the D-
1, receptor antagonists. For comparison, in these same experiments the Menk levels in other
regions were also determined. Nicotine treatment significantly lowered Menk in the nucleus
accumbens shell and the substantia nigra, but not in the nucleus accumbens core or the ventral
tegmental area. The Menk responses in the accumbens shell and the nigral brain regions were
blocked by both D-1 and D-2 as well as the nicotinic receptor antagonists. These findings
suggest that Menk systems associated with extrapyramidal and limbic brain regions are
influenced by nicotinic activation through both D-1 and D-2 receptors. This suggests the
existence of a functional interaction between nicotinic, dopaminergic and enkephalinergic
systems in these brain regions and that opioid systems may contribute to some of the effects of
tobacco use.
Disclosures: M.E. Alburges , None; P.S. Frankel, None; A.J. Hoonakker, None; G.R.
Hanson, None.
Poster
258. Molecular and Neurochemical Basis of Nicotine Addiction
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 258.8/AA11
Topic: C.16.k. Nicotine
Support: NIH Grant U01 MH69062
Propondis Foundation Fellowship to Styliani Vlachou
Title: Both GABAB receptor activation and blockade exacerbated anhedonic aspects of nicotine
withdrawal in rats
Authors: *S. VLACHOU 1 , N. PATERSON 1 , S. GUERY 2 , W. FROESTL 2 , K. KAUPMANN 2 ,
A. MARKOU 1 ;
1 Psychiatry, UCSD, Sch. of Med., La Jolla, CA; 2 Neurosci. Research, Novartis Inst. for
BioMedical Research, Novartis Pharma AG, Basel, Switzerland