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Psychopharmacology (Berl). 2006 Aug;187(2):181-8. Epub 2006 Jun 1.

Inhibition of both alpha7* and beta2* nicotinic acetylcholine receptors is necessary to prevent development of sensitization to cocaine-elicited increases in extracellular dopamine levels in the ventral striatum.

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1
Department of Biomedical Sciences, Section of Physiology University of Modena and Reggio Emilia, via Campi 287, 41100 Modena, Italy.

Abstract

RATIONALE:

Several studies have suggested that nicotine treatment can modulate the behavioral and neurochemical responses to other psychostimulants, such as cocaine.

OBJECTIVES:

The current study examined the hypothesis that nicotinic acetylcholine receptor (nAChR) blockade influences the ability of cocaine to elicit increases in extracellular dopamine levels.

MATERIALS AND METHODS:

Pharmacological studies using nicotinic antagonists as well as genetic inactivation of beta2* nAChRs were used to determine the effect of nAChR blockade on dopamine levels in ventral striatum elicited by acute or repeated administrations of cocaine in mice.

RESULTS:

Administration of mecamylamine (a general nicotinic antagonist that is not highly selective for individual nAChR subtypes) or co-administration of methyllycaconitine (a more selective antagonist of alpha7* nAChRs) with dihydro-beta-erythroidine (a more selective antagonist of beta2* nAChRs and other heteromeric nAChR subtypes) prevented sensitization of cocaine-elicited increases in extracellular DA levels in the ventral striatum in wild-type mice. In contrast, neither of the more specific antagonists alone was effective in preventing sensitization. Finally, methyllycaconitine administration prevents sensitization in beta2-/- mice but not in beta2+/+ or wild-type mice.

CONCLUSIONS:

These data indicate that inhibition of both alpha7* and beta2* nAChRs is necessary to prevent development of sensitization of cocaine-elicited increases in extracellular dopamine levels in the ventral striatum of mice.

PMID:
16826402
DOI:
10.1007/s00213-006-0419-y
[Indexed for MEDLINE]
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