title: Cross tolerance between morphine and beta-endorphin in vivo.
mesh_terms: D000700:Analgesics; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D004723:Endorphins / Q000494:pharmacology*; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D011930:Reaction Time / Q000187:drug effects
chemical_list: D000700:Analgesics; D004723:Endorphins; D010455:Peptides; D009020:Morphine