Alterations in the substance P-induced anti-nociception in the central nervous system of rats after morphine tolerance.
The present study investigated the alteration in intracerebroventricular administration of substance P-induced anti-nociception after morphine tolerance in rats. The nociceptive response latencies to noxious thermal and mechanical stimulation increased significantly after intracerebroventricular administration of SP in normal rats. The SP-induced anti-nociception decreased significantly in morphine-tolerant rats than that in opioid naive rats. The results demonstrated that SP induced significant anti-nociceptive effects in the brain in normal rats, and the SP-induced anti-nociception was attenuated significantly in morphine-tolerant rats than that in opioid naive rats, indicating an alteration in SP-induced anti-nociception in the brain after chronic morphine treatments.
Dong
Xiao-Guo
XG
Laboratory of Neurobiology, College of Life Sciences, Peking University, Beijing 100871, PR China.
Yu
Long-Chuan
LC
D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000502:physiology*; D004347:Drug Interactions; D004361:Drug Tolerance / Q000502:physiology; D008297:Male; D009020:Morphine / Q000008:administration & dosage*; D017288:Pain Threshold / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013373:Substance P / Q000008:administration & dosage*
D013373:Substance P; D009020:Morphine