The α4β2 nicotinic acetylcholine-receptor partial agonist varenicline inhibits both nicotine self-administration following repeated dosing and reinstatement of nicotine seeking in rats

The alpha 4 beta 2 nicotinic acetylcholine receptor partial agonist varenicline has greater efficacy than other pharmacotherapeutic aids for smoking cessation. This presents an opportunity to evaluate the predictive validity of rat models of nicotine taking and relapse. The aim of this study was to evaluate the ability of varenicline to attenuate nicotine self-administration and relapse, as modelled by the reinstatement model of nicotine relapse in rats. Rats were trained to respond for intravenous nicotine under a fixed ratio schedule of reinforcement. The effects of varenicline (0.3-3.0 mg/kg s.c.) on both nicotine and food self-administration and reinstatement of nicotine seeking were evaluated. Varenicline dose-dependently reduced nicotine self-administration and attenuated both nicotine prime and combined nicotine prime plus nicotine-paired cue-induced reinstatement. Varenicline had no effect on cue-induced reinstatement in the absence of a nicotine prime nor did it induce reinstatement when given alone. The effects of varenicline on nicotine-induced reinstatement of drug-seeking are consistent with the demonstrated clinical efficacy of varenicline for smoking cessation.