Regional variation in the effects of nicotine on catecholamine overflow in rat brain.

The effects of acute, repeated intermittent and continuous administration of nicotine on the overflow of noradrenaline in the ventral hippocampus and dopamine in the nucleus accumbens and striatum have been studied. Daily injections of nicotine (0.4 mg/kg(-1) for 5 days) enhanced noradrenaline and dopamine overflow in the ventral hippocampus and nucleus 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 < 0.01) by the constant infusion of nicotine at a dose of 1 mg kg(-1) per day; 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 both stimulation and desensitisation by nicotine than the catecholamine projections to the ventral hippocampus and nucleus accumbens.