Cholecystokinin: possible mediator of fever and hypothermia

Thermoregulatory effects of cholecystokinin (CCK) peptides are reviewed with special emphasis on two types of responses, that is hyperthermia (fever) and hypothermia. Central microinjection of CCK in rats induces a thermogenic response that can be attenuated by CCK-B receptor antagonists, but some authors observed a hypothermia. By contrast to its central fever-inducing effect, in rodents exposed to cold CCK-8 elicits a dose-dependent hypothermia on peripheral injection probably acting on CCK-A receptors. It is suggested that neuronal CCK may have a specific role in the development of hyperthermia, and endogenous CCK-ergic mechanisms could contribute to the mediation of fever. The possible role of CCK-ergic mediation in endotoxin (LPS) fever has revealed that while CCK-B receptors seem to be involved in the development of fever, the role of CCK-A receptors could be more complex. In particular, while rats lacking functional CCK-A receptors show an exaggerated fever response, this phenomenon may be associated with a trait different from the absence of this receptor set. The relationship between the putative CCK-ergic febrile mechanism and the established central PGE mediation needs further study.