Cold acclimation increases physiological responsiveness to intraventricular injection of beta-endorphin in pentobarbital anaesthetized rats. II. Metabolic function.
beta-endorphin administered intraventricularly into pentobarbital anaesthetized rats led to a reduction in rectal temperature and a dose dependent biphasic response in metabolic rate with increase at low doses (7-10 nmol/kg) and decrease at high doses (30-300 nmol/kg) in rats acclimated to 22 degrees. These metabolic responses to beta-endorphin were enhanced both in magnitude and in duration in rats acclimated to 5 degrees for 3 weeks, indicating an increased responsiveness to beta-endorphin. Naloxone antagonized the metabolic effects of beta-endorphin in rats acclimated to both 22 degrees and 5 degrees, indicating the metabolic effects of beta-endorphin were via the naloxone sensitive opiate receptors.
D000064:Acclimatization; D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004723:Endorphins / Q000008:administration & dosage / Q000494:pharmacology*; D004734:Energy Metabolism / Q000187:drug effects; D007276:Injections, Intraventricular; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D010424:Pentobarbital / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D001615:beta-Endorphin
D004723:Endorphins; D009270:Naloxone; D001615:beta-Endorphin; D010424:Pentobarbital