title: Morphine-induced and stimulation-produced analgesias at coincident periaqueductal central gray loci: evaluation of analgesic congruence, tolerance, and cross-tolerance.
mesh_terms: D000698:Analgesia; D000818:Animals; D002535:Cerebral Aqueduct / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D004580:Electronarcosis; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D011930:Reaction Time
chemical_list: D009020:Morphine