Differential effects of nicotinic antagonists perfused into the nucleus accumbens or the ventral tegmental area on cocaine-induced dopamine release in the nucleus accumbens of mice.
BACKGROUND
The mesolimbic dopamine (DA) system is considered a principal site for nicotine-cocaine interactions.


OBJECTIVE
The aim of this paper is to study the effects of local perfusions (through the microdialysis cannula) of nicotinic acetylcholine receptor (nAChR) antagonists in the ventral tegmental area (VTA, where mesolimbic DA cell bodies are located) or nucleus accumbens (nAc, where mesolimbic DA nerve terminals project) on cocaine-elicited increase in DA levels in the nAc of mice using intracerebral microdialysis.


RESULTS
Intra-nAc perfusion of mecamylamine (a nonselective central nicotinic antagonist) or coperfusion of methyllycaconitine (MLA, 10 nM) and dihydro-beta-erythroidine (DHbetaE, 10-100 muM) decreased cocaine-elicited increase in DA perfusate levels. In contrast, intra-nAc perfusion of MLA alone (a relatively selective antagonist of alpha7 subunit-containing nAChRs) increased, while DHbetaE (a relatively selective antagonist of heteromeric nAChR subtypes) did not alter, cocaine-elicited increase in DA perfusate levels. Intra-VTA perfusion of MLA (100 nM) or DHbetaE (100 micro M) significantly increased the cocaine-elicited increase of DA levels in the nAc or VTA, whereas DHbetaE and MLA coperfusion or mecamylamine perfusion had no significant effect.


CONCLUSIONS
These results show that intra-nAc and intra-VTA perfusion of nAChR antagonists differentially affect cocaine-elicited increase in DA levels in a region and subtype-specific manner. This suggests that multiple cholinergic/nicotinic pathways influence the effects of cocaine on mesolimbic DA neurons in complex, and sometimes opposing, patterns.
Zanetti
Lara
L
Department of Biomedical Sciences, Section of Physiology, University of Modena and Reggio Emilia, via Campi 287, 41100, Modena, Italy.
Picciotto
Marina R
MR
Zoli
Michele
M
D000157:Aconitine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001931:Brain Mapping; D003042:Cocaine / Q000494:pharmacology*; D004079:Dihydro-beta-Erythroidine / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D004347:Drug Interactions; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017551:Microdialysis; D018733:Nicotinic Antagonists / Q000494:pharmacology*; D009714:Nucleus Accumbens / Q000187:drug effects*; D011978:Receptors, Nicotinic / Q000187:drug effects*; D017557:Ventral Tegmental Area / Q000187:drug effects*; D064569:alpha7 Nicotinic Acetylcholine Receptor
D000157:Aconitine; D003042:Cocaine; D004079:Dihydro-beta-Erythroidine; D004298:Dopamine; D018733:Nicotinic Antagonists; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; C579166:Chrna7 protein, mouse