REGIONAL VARIATION IN THE EFFECTS OF NICOTINE ON CATECHOLAMINE OVERFLOW IN RAT-BRAIN

The effects of acute, repeated intermittent and continuous administrat ion of nicotine on the overflow of noradrenaline in the ventral hippoc ampus and dopamine in the nucleus accumbens and striatum have been stu died. Daily injections of nicotine (0.4 mg/kg(-1) for 5 days) enhanced noradrenaline and dopamine overflow in the ventral hippocampus and nu cleus accumbens respectively (P < 0.01 and P < 0.05) but not dopamine in the striatum in response to a nicotine challenge. The responses in the ventral hippocampus and nucleus accumbens were attenuated (P < 0.0 1) by the constant infusion of nicotine at a dose of 1 mg kg(-1) per d ay; the dopamine response in the striatum required a higher dose (4 mg kg(-1) per day) before desensitisation was observed. The data suggest that the dopamine projections to the striatum are less sensitive to b oth stimulation and desensitisation by nicotine than the catecholamine projections to the ventral hippocampus and nucleus accumbens. (C) 199 7 Elsevier Science B.V.