PT  - JOURNAL ARTICLE
AU  - Zimmerman, D M
AU  - Leander, J D
AU  - Reel, J K
AU  - Hynes, M D
TI  - Use of beta-funaltrexamine to determine mu opioid receptor involvement in the analgesic activity of various opioid ligands.
DP  - 1987 May 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 374--378
VI  - 241
IP  - 2
4099  - http://jpet.aspetjournals.org/content/241/2/374.short
4100  - http://jpet.aspetjournals.org/content/241/2/374.full
SO  - J Pharmacol Exp Ther1987 May 01; 241
AB  - 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.