title: Effect of des-Tyr1-gamma-endorphin and des-enkephalin-gamma-endorphin on active and passive avoidance behavior of rats; a dose-response relationship study.
abstract: The potency of two beta-endorphin fragments, des-Tyr1-gamma-endorphin (DT gamma E, beta E-(2-17) and des-enkephalin-gamma-endorphin (DE gamma E-(6-17) was compared on extinction of pole-jumping avoidance behavior and on retention of a one-trial step-through passive avoidance procedure. Both peptides facilitated the extinction of pole-jumping avoidance behavior and attenuated passive avoidance behavior. The gamma-type endorphin exhibited an inverted U-shaped dose-response curve on passive avoidance behavior but not on extinction of pole-jumping avoidance behavior. DE gamma E appeared to be approximately three times more potent than DT gamma E on extinction of pole-jumping avoidance behavior but one hundred times more potent on passive avoidance behavior. It is suggested that DE gamma E rather than DT gamma E represents the endogenous neuroleptic-like neuropeptide derived from beta-endorphin.
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004723:Endorphins / Q000494:pharmacology*; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D001615:beta-Endorphin
chemical_list: D004723:Endorphins; D010446:Peptide Fragments; D001615:beta-Endorphin; C018903:gamma-endorphin, des-Tyr(1)-; C033558:des-enkephalin-gamma-endorphin