PREFERENTIAL STIMULATION OF LOCOMOTOR-ACTIVITY BY VENTRAL TEGMENTAL MICROINJECTIONS OF (-)-NICOTINE

In the present study the effect of acutely administered (-)-nicotine on locomotor activity was measured after direct bilateral microinjections into the nucleus accumbens (Acb) or into the ventral tegmental area (VTA) of rats. Intrategmental (-)-nicotine (either 0.02 or 2-mu-g/side) increased locomotor activity, the effect being greatest after the lower dose. The stimulation began almost immediately and was shortlasting with peak activity occurring at 30 min. after injection. Intra-accumbal (-)-nicotine (either 0.02, 2 or 20-mu-g/side) caused only a marginal short enhancement of activity which was not dose-dependent. The time course of enhanced activity was similar to that observed after intrategmental injection. Our results indicate that the nicotine-induced hyperlocomotion may arise primarily from activation of VTA nicotinic cholinoceptors (nAchRs), whereas activation of the accumbal nAchRs is less significant in regard to this effect.