Effects of rimonabant on the reinstatement of nicotine-conditioned place preference by drug priming in rats

Drug addiction is a chronic disorder characterized by a relatively high rate of relapse even after long period of abstinence. In the present study, we used the conditioned place preference (CPP) paradigm to investigate the establishment, extinction, reinstatement and cross-reinstatement of nicotine-induced place conditioning in rats. Nicotine produced a place preference to the initially less-preferred compartment paired with its injections during conditioning (0.5 mg/kg, i.p., three drug sessions). Once established, nicotine CPP was extinguished by repeated testing. Following this extinction phase, the reinstatement of CPP was investigated. Nicotine-experienced rats were challenged with nicotine (0.5 mg/kg, i.p.) or morphine (10 mg/kg, i.p.). These priming injections of both drugs induced a marked preference for the compartment previously paired with nicotine. Furthermore, the objective of the present study was to evaluate the efficacy of CB1 cannabinoid receptor antagonist rimonabant (0.5, 1 and 2 mg/kg, i.p.) in blocking the reinstatement of nicotine-induced CPP provoked by nicotine and morphine. It was shown that rimonabant attenuated the reinstatement of nicotine-conditioned response induced by both drugs. The outcome of our studies may suggest that CB1 receptor antagonists may become a promising target for effective pharmacotherapy of tobacco addiction and polydrug abuse.