[Tolerance and reverse tolerance of nicotine on spontaneous motor activity]

Repeated administration of nicotine induces tolerance and/or reverse tolerance of spontaneous motor activity in rodents. These effects of nicotine on the spontaneous motor activity have been shown to be influenced by drug factors (e.g., doses, elapsed time after injection, period of treatment), circadian rhythm, age, sex, strain and species of animals. Although nicotinic acetylcholine receptors in the brain participate in the effects of nicotine, the development of tolerance and reverse tolerance is not sufficiently explained by changes in the receptor sites. Recently, neurochemical and behavioral studies have shown the possibility that reverse tolerance of nicotine on the spontaneous motor activity is probably concerned with the dopaminergic system through nicotinic acetylcholine receptors in the striatum or mesolimbic dopaminergic system of the rat brain. The present knowledge about the tolerance and reverse tolerance of nicotine on spontaneous motor activity is discussed in this review.