title: Use of beta-funaltrexamine to determine mu opioid receptor involvement in the analgesic activity of various opioid ligands.
abstract: Systemic administration of beta-funaltrexamine (beta-FNA) 24 hr before analgesic testing produced approximately a 10-fold parallel shift in the dose-response curves of the prototypic mu agonists morphine, I-methadone, fentanyl and etorphine in the mouse abdominal constriction test. In contrast, prior administration of beta-FNA produced no appreciable shift in the analgesic dose-response curve of the selective kappa agonist, U-50, 488H. These results suggest that beta-FNA is selective for mu over kappa receptors under the conditions used in this study. The dose-response curves for ethylketazocine and proxorphan were affected only to a small extent by beta-FNA pretreatment, suggesting that these compounds have analgesic actions mediated primarily through nonmu, probably kappa receptors. The dose-response curves for cyclazocine, buprenorphine, butorphanol, nalorphine and nalbuphine were shifted markedly to the right and frequently not in a parallel fashion by the prior administration of beta-FNA. These results seem to indicate a major role for the mu receptor in the analgesic actions of these compounds.
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000698:Analgesia; D000818:Animals; D001681:Biological Assay; D002047:Buprenorphine / Q000494:pharmacology; D002077:Butorphanol / Q000494:pharmacology; D003496:Cyclazocine / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D016314:Ethylketocyclazocine; D005048:Etorphine / Q000494:pharmacology; D005283:Fentanyl / Q000494:pharmacology; D008691:Methadone / Q000494:pharmacology; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009266:Nalbuphine / Q000494:pharmacology; D009269:Nalorphine / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D011957:Receptors, Opioid / Q000378:metabolism*; D017450:Receptors, Opioid, mu
chemical_list: D011759:Pyrrolidines; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D002047:Buprenorphine; D005048:Etorphine; D016314:Ethylketocyclazocine; D009271:Naltrexone; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; C024524:beta-funaltrexamine; D009020:Morphine; D003496:Cyclazocine; D009266:Nalbuphine; D002077:Butorphanol; D009269:Nalorphine; D008691:Methadone; D005283:Fentanyl