EFFECT OF CHRONIC NICOTINE TREATMENT AND WITHDRAWAL ON RAT STRIATAL D1 AND D2 DOPAMINE-RECEPTORS

The effects on rat striatal dopamine receptors after chronic nicotine administration (3 and 12mg kg-1 day-1), and after withdrawal from chronic nicotine (12 mg kg-1 day-1), were studied. After 21 days of continuous minipump infusion, the control (saline) and nicotine-treated rats were killed. The nicotine-withdrawal rats were killed on day 28, 7 days after pump removal: Radioligand studies were performed to determine D1 ([H-3]SCH23390) and D2 ([H-3]spiperone) striatal dopamine receptor affinity (K(d)) and maximum binding (B(max)). Dopamine inhibition of antagonist binding at 3 concentrations and the effect of 0.3 mM GTP on binding affinity were examined. No statistically significant differences between control and nicotine treatment or withdrawal groups were noted in either D1 or D2 receptor K(d) or B(max). Although nicotine has been shown to affect nigrostriatal dopamine release, chronic treatment does not appear to alter overall striatal dopaminergic receptor binding parameters.