Changes in sensitivity to operant effects of dopaminergic and cholinergic agents following morphine withdrawal in rats.
Rats trained to bar-press on either a FI 15 sec or FR 30 schedule for water reinforcement were administered various doses of appomorphine, haloperidol, pilocarpine and scopolamine both before and 1--4 months after a 3-day period of continuous morphine administration. All drugs monotonically depressed response rates on both schedules with increasing dose. Chronic morphrine administration produced a persistent increase in sensitivity to apomorphine and pilocarpine and a persistent decrease in sensitivity to haloperidol and scopolamine. The results suggest that both dopaminergic and cholinergic supersensitivity are likely to be involved in protracted abstinence phenomena.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects*; D004298:Dopamine / Q000502:physiology*; D005260:Female; D006220:Haloperidol / Q000494:pharmacology; D006801:Humans; D009020:Morphine / Q000494:pharmacology*; D010862:Pilocarpine / Q000494:pharmacology*; D051381:Rats; D012055:Reinforcement Schedule; D012601:Scopolamine / Q000494:pharmacology*; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*; D013997:Time Factors
D010862:Pilocarpine; D009020:Morphine; D012601:Scopolamine; D006220:Haloperidol; D001058:Apomorphine; D004298:Dopamine