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Psychopharmacology (Berl). 2007 Nov;194(4):463-73. Epub 2007 Jul 8.

Reinforcement enhancing effect of nicotine and its attenuation by nicotinic antagonists in rats.

Author information

1
Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15260, USA. xiuliu@pitt.edu

Abstract

RATIONALE:

Recent studies have demonstrated that nicotine can enhance operant responding for other nonpharmacological reinforcing stimuli. However, the nature of the reinforcement-enhancing effect of nicotine remains largely unknown.

OBJECTIVE:

The present study determined the dose dependency of the ability of nicotine to increase lever-pressing responses maintained by a compound visual stimulus (VS) in rats and examined its sensitivity to pharmacological antagonism of nicotinic acetylcholine receptors (nAChRs).

MATERIALS AND METHODS:

Male Sprague-Dawley rats were trained in daily 1-h sessions to lever press for delivery of a VS (1 s lever light on and 60 s house light off) on a fixed ratio 5 schedule. During these sessions, eight scheduled response-independent intravenous infusions of nicotine (total amount: 0, 0.06, 0.12, 0.24, 0.48 mg kg(-1) h(-1)) were delivered. In pharmacological tests, a nonselective nAChR antagonist mecamylamine, alpha4beta2-selective antagonist dihydro-beta-erythroidine (DHbetaE), and alpha7-selective antagonist methyllycaconitine (MLA) were administered in different groups of rats 30 min before the session.

RESULTS:

The VS maintained a moderate level of lever-pressing responses and nicotine dose-dependently increased responses for the VS presentations. Preteatment of mecamylamine and DHbetaE but not MLA significantly attenuated the nicotine-enhanced responding. However, mecamylamine had no effect on responding for the VS in rats that received scheduled saline infusions.

CONCLUSIONS:

These results demonstrate dose dependency of the reinforcement-enhancing effect of nicotine and suggest that activation of the alpha4beta2- but not alpha7-containing nAChRs may mediate this effect.

PMID:
17616849
PMCID:
PMC2826146
DOI:
10.1007/s00213-007-0863-3
[Indexed for MEDLINE]
Free PMC Article
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