Attenuation by pimozide of the suppressant effect of d-amphetamine on operant behaviour.
The interaction between pimozide (a selective D2-dopamine receptor antagonist) and d-amphetamine on the operant performance of rats maintained under variable-interval schedules of positive reinforcement was examined. In Experiment 1, eight rats responded under variable-interval 30-s and variable-interval 300-s. Pimozide (0.0625, 0.125, 0.25, 0.5 mg/kg) suppressed performance maintained under both schedules in a dose-dependent manner, the degrees of suppression being equivalent in the two schedules. In Experiment 2, 12 rats responded under the same schedules. d-Amphetamine (0.1-3.2 mg/kg) suppressed performance under both schedules, the degree of suppression being somewhat greater in the case of variable-interval 30-s. Pre-treatment with pimozide (0.0625, 0.125 mg/kg) significantly attenuated the suppressant effect of d-amphetamine under both schedules. It is suggested that D2-dopamine receptors may be involved in mediating the suppressant effect of d-amphetamine on operant behaviour.
D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D003913:Dextroamphetamine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D010868:Pimozide / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule
D010868:Pimozide; D003913:Dextroamphetamine