The effects of nitric oxide on the acquisition and expression of nicotine-induced conditioned place preference in mice.

In the present study, the possible role of nitric oxide on the conditioned place preference (CPP) induced by nicotine in mice was investigated. Intraperitoneal (i.p.) injections of nicotine (1 mg/kg) and the nitric oxide (NO) precursor, L-arginine (200 and 500 mg/kg), produced significant place preference. However, injection of mecamylamine (0.05 and 0.1 mg/kg; i.p.) or the NO synthase (NOS) inhibitor, L-Nitro-amino-methyl-ester, L-NAME (5-20 mg/kg; i.p.), had no effect. Ineffective doses of nicotine in combination with ineffective doses of L-arginine produced significant place preference. Administration of L-arginine (50, 100 and 150 mg/kg; i.p.) on the test day reduced the expression of nicotine-induced place preference. Nicotine injection (0.25, 0.5 and 0.75 mg/kg) on the test day reduced the expression of place preference induced by L-arginine, while both mecamylamine (0.05 and 0.1 mg/kg) and L-NAME (5, 10 and 20 mg/kg) inhibited the acquisition of place preference induced by nicotine (1 mg/kg) and L-arginine (200 mg/kg). Moreover, neither of the antagonists reduced the expression of nicotine- or L-arginine-induced place preference. It is suggested that nitric oxide may play an important role in nicotine-induced place preference.