CHRONIC NICOTINE TREATMENT POTENTIATES BEHAVIORAL-RESPONSES TO DOPAMINERGIC DRUGS IN RATS

In the present study, the behavioral effects of apomorphine, methamphe tamine, and haloperidol were examined in nicotine-treated rats. All an imals were SC administered nicotine at a dose of 0.5 mg/kg or saline o nce daily for 14 days. Hyperlocomotion induced by apomorphine (0.2 mg/ kg, IP) and methamphetamine (1.0 mg/kg, IP) was greater in nicotine-tr eated rats than in control rats. Stereotyped behaviors induced by apom orphine (1.0 mg/kg, IP) and methamphetamine (5.0 mg/kg, IP) were also potentiated in nicotine-treated rats. However, the incidence of catale psy induced by haloperidol (0.25-1.5 mg/kg, IP) was slightly lower in nicotine-treated rats. These results suggest that chronic nicotine tre atment may increase the susceptibility of the dopaminergic system to d opaminergic drugs.