Abstract: Thirty-four female albino rats of Holtzman strain were observed in this experiment as models of rotational behavior with unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal system in the brain. Three behavioral observations were conducted in a special and automatic rotometer. Only the data collected on those animals that had more than 85% dopamine depletion at the lesion side and had shown dominantly ipsilateral circling behavior (toward the lesion side) were analyzed and discussed. The 34 female rats all qualified. The effects of cocaine on rotational behavior in rats as observed in this experiment are as follows:It is obvious that cocaine produced a stereotyped and rotational behavior; the action was rapid. Different doses of cocaine produced different effects on rotational behavior in rats.A single exposure to cocaine significantly produced a long-lasting (at least one week) facilitation of rotational behavior in rats. It suggests that it is not necessary to repeatedly administer psychomotor stimulant drugs to produce long-lasting changes in brain and behavior.

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