title: Role of peripheral and central opioid activity in analgesia induced by restraint stress.
abstract: Rats subjected to prolonged restraint showed an increase in tail flick latency which outlasted the period of restraint by 15 min. This restraint could be blocked but not reversed by 1 mg/kg of naltrexone hydrochloride given subcutaneously. Naltrexone methobromide, administered subcutaneously in doses of 10 or 25 mg/kg, did not block the analgesia indicating that peripheral opioid receptors were probably not involved. Naltrexone hydrochloride was shown to have no effect on brain tryptophan uptake in restrained rats, a neurochemical event which had previously been shown to be critical to restraint-induced analgesia.
mesh_terms: D000698:Analgesia; D000818:Animals; D001933:Brain Stem / Q000378:metabolism; D004723:Endorphins / Q000502:physiology*; D008297:Male; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds; D051381:Rats; D011957:Receptors, Opioid / Q000502:physiology; D012149:Restraint, Physical; D013312:Stress, Physiological / Q000209:etiology / Q000503:physiopathology*; D014364:Tryptophan / Q000378:metabolism
chemical_list: D004723:Endorphins; D000644:Quaternary Ammonium Compounds; D011957:Receptors, Opioid; C032257:methylnaltrexone; D009271:Naltrexone; D014364:Tryptophan