Effect of chlorpromazine on mouse ambulatory activity sensitization caused by (+)-amphetamine

Abstract

Abstract The development of sensitization to the ambulation-increasing effect of (+)-amphetamine (2·5 mg kg−1) was found to be dose-dependently inhibited when 1 or 2 mg kg−1 chlorpromazine was administered concomitantly, and the sensitization to (+)-amphetamine was almost completely suppressed when co-administered with 4 mg kg−1 chlorpromazine. Following a challenge dose of 2·5 mg kg−1 (+)-amphetamine, mice pretreated with (+)-amphetamine alone or with (+)-amphetamine plus 1 or 2 mg kg−1 chlorpromazine showed similar marked enhancement of the sensitization. However, mice that had been given (+)-amphetamine plus 4 mg kg−1 chlorpromazine displayed only slight enhancement of the effect compared with the activity level in saline-pretreated mice.