CHRONIC EFFECTS OF NICOTINE ON MESOLIMBIC DOPAMINERGIC SYSTEM IN RATS

Rats were pretreated with saline or nicotine (1.5 mg/kg/day) by subcutaneously implanting each animal with an Alzet osmotic minipump which continuously released saline or nicotine (1.5 mg/kg/day) for 14 days. The behavioral and biochemical effects of nicotine on the dopaminergic neuronal system in rat nucleus accumbens were examined. It was found that chronic nicotine treatment increased the affinity of L-[H-3]nicotine binding site in the nucleus accumbens. This treatment also potentiated the ability of (+)-amphetamine, but not high potassium, to stimulate formation and release of [H-3]dopamine in tissue slices from rat nucleus accumbens. Chronic nicotine treatment did not alter the characteristics of [H-3]spiperone binding site, the rate of dopamine turnover and the concentrations of gamma-aminobutyric acid in the nucleus accumbens.