title: Oral self-administration of morphine in rats.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001522:Behavior, Animal; D003216:Conditioning, Operant; D008297:Male; D009020:Morphine / Q000008:administration & dosage*; D051381:Rats; D012646:Self Administration
chemical_list: D009020:Morphine