Effects of drugs on schedule-controlled behavior in rats during chronic haloperidol administration.
Dose-response curves for haloperidol, phencyclidine, morphine, meperidine and cimetidine were determined in rats trained under a multiple fixed-ratio 30, fixed-interval 5-min schedule of reinforcement. Haloperidol, morphine, meperidine and cimetidine decreased both fixed-ratio and fixed-interval rates of responding. Phencyclidine had a biphasic effect on overall response rates in both components: response rates increased and then decreased as the dose was increased. After these dose-response curve determinations, chronic daily treatment with haloperidol (0.3 mg/kg i.p.), after the behavioral session, was initiated. After 6 weeks of chronic treatment with haloperidol, the dose-response curves were redetermined for all the drugs, while haloperidol continued to be administered after the session. During chronic haloperidol administration, the dose-effect curves for haloperidol, morphine, meperidine and cimetidine were not modified consistently; however, chronic haloperidol treatment enhanced the effects of phencyclidine as shown by a shift of the dose-response curves to the left during both fixed-ratio and fixed-interval components. Four weeks after chronic haloperidol had been discontinued, low doses of haloperidol produced smaller rate-decreasing effects than they had previously.
D000818:Animals; D002927:Cimetidine / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006220:Haloperidol / Q000494:pharmacology*; D008297:Male; D008614:Meperidine / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology; D010622:Phencyclidine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule; D013997:Time Factors
D009020:Morphine; D002927:Cimetidine; D008614:Meperidine; D010622:Phencyclidine; D006220:Haloperidol