Blockade effect of mu and kappa opioid antagonists on the anti-nociception induced by intra-periaqueductal grey injection of oxytocin in rats.
Intra-periaqueductal grey (PAG) injection of 1 nmol of oxytocin induced significant increases in hindpaw withdrawal latency (HWL) to thermal and mechanical stimulation in rats. The anti-nociceptive effect of oxytocin was attenuated significantly by subsequent intra-PAG injection of the mu opioid antagonist beta-funaltrexamine (beta-FNA) and the kappa opioid antagonist nor-binaltorphimine (nor-BNI), but not by the delta antagonist naltrindole. The results demonstrated that mu and kappa opioid receptors, not delta receptors, were involved in the oxytocin-induced anti-nociception in PAG of rats.
Ge
Yuan
Y
Department of Physiology, College of Life Sciences, and Center for Brain and Cognitive Science, Peking University, Beijing 100871, People's Republic of China.
Lundeberg
Thomas
T
Yu
Long-Chuan
LC
D000700:Analgesics / Q000008:administration & dosage*; D000818:Animals; D007276:Injections, Intraventricular; D008297:Male; D009292:Narcotic Antagonists / Q000494:pharmacology; D010121:Oxytocin / Q000008:administration & dosage* / Q000502:physiology; D010147:Pain Measurement / Q000187:drug effects; D010487:Periaqueductal Gray / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017473:Receptors, Opioid, kappa / Q000037:antagonists & inhibitors* / Q000502:physiology; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors* / Q000502:physiology
D000700:Analgesics; D009292:Narcotic Antagonists; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D010121:Oxytocin