Opioid antagonists and butorphanol dependence.
Butorphanol has been known to act on mu-, delta-, and kappa-opioid receptors, mu- and possibly delta-receptors are thought to mediate morphine dependence. Relative to morphine, butorphanol has a higher affinity for mu- and delta-receptors. In the present study, beta-funaltrexamine (beta-FNA) and naltrindole (NTI) (nonequilibrium mu- and delta-antagonist, respectively) were used to precipitate withdrawal in butorphanol-dependent rats. It was found that beta-FNA (12, 24, 48, and 100 nM) did not elicit significant withdrawal behaviors, while NTI caused teeth-chattering (100 nM), wet shakes (100 nM), forepaw tremors (24 nM), yawning (48 and 100 nM), ejaculation (24 nM), and urination (100 nM). The present results indicate that delta-opioid receptors may be involved in mediating butorphanol dependence, while the involvement of mu-opioid receptors needs to be further investigated.
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Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson 39216.
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D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002077:Butorphanol / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D009019:Morphinans / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology*; D009293:Opioid-Related Disorders / Q000523:psychology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017465:Receptors, Opioid, delta / Q000187:drug effects; D017450:Receptors, Opioid, mu / Q000187:drug effects; D013375:Substance Withdrawal Syndrome / Q000523:psychology
D007211:Indoles; D009019:Morphinans; D009292:Narcotic Antagonists; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D009271:Naltrexone; C024524:beta-funaltrexamine; C055382:naltrindole; D002077:Butorphanol