title: [Is there any endogenous morphine antagonist?].
mesh_terms: D000818:Animals; D004361:Drug Tolerance; D004723:Endorphins / Q000037:antagonists & inhibitors*; D051379:Mice; D009020:Morphine / Q000037:antagonists & inhibitors; D051381:Rats
chemical_list: D004723:Endorphins; D009020:Morphine