title: Differences in the effects of mu- and delta-opioid receptor antagonists upon plasma corticosterone levels in stressed mice.
abstract: The effects of intraperitoneal injections of two opioid antagonists on plasma corticosterone levels in stressed mice was investigated. The effects of the mu-opioid receptor antagonist naloxone was dependent on the dose used. Low doses (0.5 and 1 mg/kg) potentiated the elevation of plasma corticosterone observed in saline treated or ether stressed mice, whereas a higher dose (10 mg/kg) produced the opposite effect. The delta-opioid receptor antagonist ICI 154,129 had no significant effect on corticosterone levels. The findings suggest that mu- rather than delta-opioid receptors are important in modifying corticosterone responses to stress and raise the question as to specificity of naloxone at doses above 1 mg/kg.
mesh_terms: D000818:Animals; D003345:Corticosterone / Q000097:blood*; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D004986:Ether / Q000494:pharmacology; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000187:drug effects*; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D013312:Stress, Physiological / Q000097:blood*
chemical_list: D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D004986:Ether; D009270:Naloxone; D004743:Enkephalin, Leucine; C036405:ICI 154129; D003345:Corticosterone