Increases in dopamine utilization in certain limbic dopamine terminal populations after a short period of intermittent exposure of male rats to cigarette smoke

Summary

By means of a Walton smoke machine male rats were exposed to cigarette smoke from 1 to 4 cigarettes. Dopamine (DA) levels and utilization in the telencephalon were measured by quantitative histofluorimetry in discrete DA nerve terminal systems of the neostriatum, nucleus accumbens and tuberculum olfactorium. Exposure to unfdtered but not to filtered (Cambridge glass fibre filter) cigarette smoke resulted in a dose-dependent increase in DA utilization in the diffuse types of DA nerve terminal systems in the anterior nucleus accumbens and the lateral posterior tuberculum olfactorium. After exposure to the smoke from 4 cigarettes also an increase in DA utilization was observed in the dotted type (also cholecystokinin [CCK] positive) of DA nerve terminals of the nucleus accumbens (posterior part). The DA utilization in various parts of the neostriatum and in the dotted type of DA nerve terminals in the medial posterior tuberculum olfactorium were unaffected by acute intermittent exposure to cigarette smoke. The DA levels in the various DA nerve terminal systems in neostriatum, nucleus accumbens and tuberculum olfactorium were unaffected with the exception of the dotted and CCK positive type of DA nerve terminals of the nucleus accumbens, where a small reduction of the DA stores was shown following acute intermittent exposure to smoke from 4 cigarettes. The effects induced by exposure to the cigarette smoke in the limbic DA terminals were counteracted by mecamylamine pretreatment. It is suggested that the nicotine component of the cigarette smoke via activation of nicotinic cholinergic receptors can enhance DA release in discrete DA nerve terminal systems of the nucleus accumbens and tuberculum olfactorium. These actions may at least in part mediate the euphoria induced by inhalation of cigarette smoke.