The acquisition of responding with conditioned reinforcement: effects of cocaine, (+)-amphetamine and pipradrol.

1 A procedure for examining the acquisition of a lever-pressing operant with conditioned reinforcement was used to compare the effects of three psychomotor stimulants. 2 Hungry rats were trained to associated and auditory tone (i.e., conditioned reinforcer) with food. Preference for the tone was then measured after treatment with pipradol (5, 10, 15 mg/kg), cocaine (1, 5, 10 mg/kg) or (+)-amphetamine (0.5, 1.5, 5.0 mg/kg). 3 In agreement with previous data, 10 mg/kg of pipradrol enhanced the effect of conditioned reinforcement whereas animals treated with any of the doses of (+)-amphetamine showed no effect. 4 Rats treated with cocaine (1 or 5 mg/kg) showed an effect of conditioned reinforcement but the effect was not significantly greater than in controls. 5 The present data suggest important differences in enhancement of responding for conditioned reinforcement by various drugs in the psychomotor stimulant class. These differences in turn may be related to the pharmacological actions of these compounds on release of catecholamines from different storage pools.