title: Conditioned suppression by a stimulus associated with nalorphine in morphine-dependent monkeys.
abstract: Three rhesus monkeys, physically dependent on morphine, were trained to press a lever for food on a fixed ratio of 10 responses. A tone, initially a neutral stimulus, was aperiodically presented every third or fourth session, 5 min before and after the intravenous injection of nalorphine, a morphine antagonist which produces an immediate withdrawal syndrome in morphine-dependent monkeys. After several sessions, conditioned suppression of food-lever response rate was observed. Conditioned bradycardia, emesis, and excessive salivation also occurred. In 40 to 45 sessions the conditioned suppression of food-lever response rate and the conditioned autonomic changes were extinguished by presenting pairings of a tone and saline injection. The monkeys were then reconditioned by presenting the tone aperiodically, every third or fourth session, 5 min before and after the intravenous injection of nalorphine. Results were similar to the initial conditioning sessions. Two rhesus monkeys not dependent on morphine were stabilized on a food schedule similar to that used for the first three monkeys. These monkeys showed no change in food-lever response rate during or after nalorphine injections.
mesh_terms: D000818:Animals; D001919:Bradycardia / Q000139:chemically induced; D003216:Conditioning, Operant; D005108:Extinction, Psychological / Q000187:drug effects; D005260:Female; D005502:Food; D000882:Haplorhini; D006801:Humans; D008297:Male; D009021:Morphine Dependence; D009269:Nalorphine / Q000494:pharmacology*; D011930:Reaction Time; D012472:Salivation; D013016:Sound; D013375:Substance Withdrawal Syndrome; D014839:Vomiting / Q000139:chemically induced
chemical_list: D009269:Nalorphine