title: Body temperature effects of opioids administered into the periaqueductal grey area of rat brain.
abstract: The ability of opioids to influence rectal temperature after injection into the periaqueductal grey region (PAG) of rat brain was investigated. Both morphine and beta-endorphin caused a dose-dependent increase in rectal temperature of up to 2 degrees C. By using selective ligands of the subclasses of opiate receptor such as [D-Ala2,D-Leu5]enkephalin for delta-receptors and ethylketocyclazocine, dynorphin(1-17) and dynorphin(1-8) for kappa-receptors, it was possible to show that neither the delta- nor the kappa-opiate receptor was involved in the hyperthermic response. However, [D-Ala2,MePhe4,Gly-ol5]enkephalin (DAGO), a mu-receptor ligand, did produce a dose-dependent hyperthermia. The ability of naltrexone, an opiate receptor antagonist, to reverse the hyperthermia induced by beta-endorphin and DAGO suggests that the opioid-stimulated increase in body temperature via the PAG is mediated through the mu-opiate receptor. Since the application of opioids to the PAG produces a hyperthermic response, it is possible that this brain site may have a role in the peptidergic control of body temperature.
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects*; D004723:Endorphins / Q000494:pharmacology*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009271:Naltrexone / Q000494:pharmacology; D010487:Periaqueductal Gray / Q000187:drug effects*; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects; D013997:Time Factors
chemical_list: D004723:Endorphins; D011957:Receptors, Opioid; D009271:Naltrexone; D009020:Morphine