Cholecystokinin and morphine-induced hypothermia

Abstract

The effects of cholecystokinin-8 sulfate (CCK-8), cholecystokinin-8 unsulfate (CCK-8U), cholecystokinin-4 (CCK-4), caerulein and morphine on mice core body temperature have been studied in the present work. Subcutaneous injection of different doses of caerulein (0.05, 0.1 and 0.5 mg/kg), CCK-8 (0.05, 0.1 and 0.25 mg/kg) and morphine (10, 20 and 30 mg/kg) induced hypothermia. CCK-8U and CCK-4 did not elicit any response. The hypothermic response induced by caerulein, a CCK-related decapeptide but not morphine was decreased by selective CCK A receptor antagonist MK-329. However, the hypothermia induced by morphine but not caerulein was reduced by opioid antagonist naloxone. When morphine plus caerulein was administered a higher hypothermia was induced. Pretreatment of animals with l-365 260, a selective CCK B receptor antagonist did not alter the hypothermia induced by the drugs. The response induced by combination of the both drugs was decreased by MK-329. Administration of CCK antagonists MK-329 and l-365 260 to mice did not exert any effect on temperature. It is concluded that the CCK A receptor mechanism may be involved in the hypothermic effect of CCK agonists or morphine, while opioid receptor mechanism is not involved in CCK receptor agonists' response.