title: Enkephalin-like character and analgesia.
abstract: The opioid activities of enkephalin analogues bearing D- or L-aminopentane-sulfonic/phosphonic acid at position 5 were studied in vitro, in electrically stimulated longitudinal muscle strip of guinea-pig ileum and mouse vas deferens preparations and in vivo in the rat tail-flick test. Using their in vitro effects Met-enkephalin-like, beta-endorphin-like, (nor)morphine-like and derivatives of intermediate character could be differentiated. Correlating the in vitro activities with the analgesic activity in vivo it is concluded that the enkephalin-like character in a pentapetide may hinder the expression of analgesic activity, when the compounds are given into the cerebroventricular system.
mesh_terms: D000700:Analgesics; D000818:Animals; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000008:administration & dosage / Q000494:pharmacology*; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D051381:Rats; D011930:Reaction Time / Q000187:drug effects; D013329:Structure-Activity Relationship
chemical_list: D000700:Analgesics; D004723:Endorphins; D004745:Enkephalins