Preferential Stimulation of Locomotor Activity by Ventral Tegmental Microinjections of (—)‐Nicotine

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Abstract
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 μg/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 μg/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.