Amphetamine sensitization of stress-induced turning in animals given unilateral dopamine transplants in infancy

Infant rats given bilateral dopamine-depleting brain lesions and unilateral transplants of embryonic nigral tissue develop turning in response to both amphetamine and stress. However, stress-induced turning did not develop unless animals were previously exposed to amphetamine, and was greatest in animals exposed early to the drug. These findings suggest that amphetamine alters certain properties of the transplanted cells so as to enhance their functional capacity.