title: Potent tetrapeptide enkephalins.
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001681:Biological Assay; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology*; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D007700:Kinetics; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009842:Oligopeptides / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D004723:Endorphins; D004745:Enkephalins; D009842:Oligopeptides