Cholecystokinin and morphine-induced hypothermia

The effects of cholecystokinin-8 sulfate (CCK-8), cholecystokinin-8 unsulfa te (CCK-8U), cholecystokinin-4 (CCK-4), caerulein and morphine on mice core body temperature have been studied in the present work. Subcutaneous injec tion 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 hypothermi a. CCK-8U and CCK-4 did not elicit any response. The hypothermic response i nduced by caerulein, a CCK-related decapeptide but not morphine was decreas ed by selective CCK, receptor antagonist MK-329. However, the hypothermia i nduced by morphine but not caerulein was reduced by opioid antagonist nalox one. When morphine plus caerulein was administered a higher hypothermia was induced. Pretreatment of animals with L-365 260, a selective CCK, receptor antagonist did not alter the hypothermia induced by the drugs. The respons e induced by combination of the both drugs was decreased by MK-329. Adminis tration of CCK antagonists MK-329 and L-365 260 to mice did not exert any e ffect on temperature. It is concluded that the CCK, receptor mechanism may be involved in the hypothermic effect of CCK agonists or morphine, while op ioid receptor mechanism is not involved in CCK receptor agonists' response. (C) 1999 Elsevier Science B.V. All rights reserved.