title: Time-dependent disruptive effects of periaqueductal gray stimulation on development of morphine tolerance.
mesh_terms: D000698:Analgesia; D000818:Animals; D002535:Cerebral Aqueduct / Q000502:physiology*; D004056:Differential Threshold; D004361:Drug Tolerance; D004558:Electric Stimulation; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D010146:Pain / Q000209:etiology; D051381:Rats; D013997:Time Factors
chemical_list: D009020:Morphine