This study was aimed at evaluating the possible effects of nitrergic drugs (L-arginine and NG-nitro-L-arginine methyl ester (L-NAME)) on nicotine reward and dopamine-related behaviors (locomotion, sniffing, rearing, and compartment entering) in rats. The purpose was to determine whether modulation of these behaviors is involved in the possible effect of nitrergic drugs on nicotine-induced place conditioning in rats. Conditioning scores and dopamine-related behaviors were counted in all animals. Results showed that nicotine (1.5 mg/kg, intraperitoneally (i.p.)), but not L-arginine or L-NAME, induced conditioned place preference (CPP); however, nicotine reduced the locomotion and rearing and L-arginine reduced locomotion and sniffing, but L-NAME did not change these behaviors. L-arginine decreased the expression of nicotine-induced CPP and locomotion, rearing and sniffing. Although pretreatment with L-arginine abolished acquisition of nicotine place conditioning, it did not affect dopamine-related behaviors on the testing day. Additionally, although pre-exposure of rats to various doses of L-NAME did not attenuate expression of CPP, it inhibited acquisition of CPP produced by nicotine injection and significantly reduced some of dopamine-related behaviors both in acquisition and expression of nicotine-induced CPP. In conclusion, interaction of nitric oxide and nicotine in the CPP paradigm may be, at least in part, dependent on alteration of dopamine-related behaviors by nitric oxide.
Key words: Nicotine, nitric oxide, place conditioning, dopamine-related behaviors.
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