Influence of peptides on reduced response of rats to electric footshock after acute administration of morphine.
Acute treatment of rats with morphine (10 mg/kg) resulted in a marked reduction of motor response to inescapable electric footshock (EFS). Nalorphine (2mg/kg) antagonized this action of morphine. Pretreatment with synthetic ACTH 1-24 (10 IU) 60 min prior to testing also inhibited this morphine-induced reduction, whereas other ACTH-like peptides, lacking corticotrophic activity, were ineffective. ACTH 1-24 had no effect on the response of adrenalectomized rats to EFS after morphine. In intact rats dexamethasone pretreatment 4 hr prior to testing also antagonized the action of morphine on EFS. Taken together these findings suggest that ACTH 1-24 interferes with the antinociceptive action of morphine and that the integrity of the adrenal is essential for demonstration of this antagonism.
D000311:Adrenal Glands / Q000502:physiology; D000315:Adrenalectomy; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003366:Cosyntropin / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004597:Electroshock; D005260:Female; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology; D009020:Morphine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D009269:Nalorphine / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D010455:Peptides; D003366:Cosyntropin; D009020:Morphine; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D009074:Melanocyte-Stimulating Hormones; D009269:Nalorphine