Effects of naloxone, diprenorphine, buprenorphine and etorphine on unpunished and punished food-reinforced responding in the squirrel monkey.
The effects of naloxone and three oripavine derivatives, diprenorphine, an antagonist, buprenorphine, a mixed agonist-antagonist, and etorphine, an agonist, were examined on food-reinforced responding in squirrel monkeys. Behavior was maintained under a multiple-component 1-min variable-interval schedule in which 12-min periods of unpunished responding alternated with 4-min periods in which each response produced a brief electric shock to the tail. Daily sessions were 1 hr. Responding in the two components was not differentially affected by any of the drugs. Naloxone decreased responding in both components only slightly at high doses (ED50 greater than 10 mg/kg). In contrast, the three oripavines produced prominent dose-related decreases in responding with the following order of potency for the nonpunishment component: etorphine (ED50 = 0.0005 mg/kg) greater than buprenorphine (ED50 = 0.02 mg/kg) greater than diprenorphine (ED50 = 0.11 mg/kg). Etorphine had a short duration of action (approximately 1 hr) whereas the actions of diprenorphine (1.0 mg/kg) and buprenorphine (0.1 mg/kg) persisted for 24 to 48 hr. Concurrent administration of naloxone (0.1 and 1.0 mg/kg) antagonized the response rate-decreasing effects of etorphine and buprenorphine in a dose-dependent manner (i.e., dose-response curves were shifted to the right) but failed to block the effects of diprenorphine. Although all three oripavines produced comparable decreases in food-reinforced responding, there are qualitative as well as quantitative differences between the drugs. Diprenorphine appears to act through a different mechanism from that of buprenorphine and etorphine.
D000818:Animals; D002047:Buprenorphine / Q000494:pharmacology*; D004174:Diprenorphine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005048:Etorphine / Q000494:pharmacology*; D005260:Female; D008297:Male; D009019:Morphinans / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D011678:Punishment; D012054:Reinforcement, Psychology; D012453:Saimiri
D009019:Morphinans; D004174:Diprenorphine; D009270:Naloxone; D002047:Buprenorphine; D005048:Etorphine