title: beta-Endorphin-induced analgesia is inhibited by synthetic analogs of beta-endorphin.
abstract: Competitive antagonism of human beta-endorphin (beta h-EP)-induced analgesia by synthetic beta h-EP analogs with high in vitro opiate receptor binding to in vivo analgesic potency ratio has been demonstrated. A parallel shift of the dose-response curve for analgesia to the right was observed when either beta h-EP or [ Trp27 ] -beta h-EP was coinjected with various doses of [Gln8, Gly31 ]-beta h-EP-Gly-Gly-NH2, [Arg9,19,24,28,29]-beta h-EP, or [ Cys11 ,26, Phe27 , Gly31 ]-beta h-EP. It was estimated that the most potent antagonist, [Gln8, Gly31 ]-beta h-EP-Gly-NH2, is at least 200 times more potent than naloxone.
mesh_terms: D000698:Analgesia; D000818:Animals; D001681:Biological Assay; D001921:Brain / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004723:Endorphins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D009270:Naloxone / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology; D011957:Receptors, Opioid / Q000378:metabolism; D013329:Structure-Activity Relationship; D001615:beta-Endorphin
chemical_list: D004723:Endorphins; D011957:Receptors, Opioid; D009270:Naloxone; D001615:beta-Endorphin