CCK-8 induces fever-like regulated hyperthermia and symptoms of sickness behavior in mice: A biotelemetric study

Abstract In earlier studies it has been found that rats respond to intracerebroventricular (i.c.v.) injection of cholecystokinin-octapeptide (CCK-8) with a febrile response characterized by rises of heat production and core temperature together with tail-skin vasoconstriction mediated by CCK2 receptors. Biotelemetric investigations of the same species have additionally shown that CCK-induced fever is accompanied by decreased locomotor activity. Similar data for mice have not been reported so far. In the present studies C57BL/6 mice were infused i.c.v. for 3 days with CCK-8 to see effects on body core temperature, locomotor activity, food intake and body weight. Biotelemetric monitoring disclosed a rise in daylight core temperature and a fall of night-time locomotor activity both lasting beyond the time of i.c.v. infusions. Food intake was suppressed only during infusion, while a significant decrease of body weight was sustained after the end of CCK-8 infusion. It is concluded that similar to rats mice also respond to i.c.v. infusion of CCK-8 with a fever-like (regulated) hyperthermia and some components of sickness behavior as measured by biotelemetry, and thus a CCK-mediated mechanism may contribute to fever genesis also in mice.