Interferons and central regulation of feeding.

Interferons (IFNs) are immunomodulators with neuromodulatory activities. To study the effects of IFNs on the central regulation of feeding, rats were subjected to various applications. The results show the following. 1) Intracerebroventricular microinfusion of rat IFN (15-225 IU/rat) decreased short-term (2-h) food intake in rats. Computerized analysis of behavioral patterns demonstrated a reduction of meal size and meal duration, whereas meal frequency slightly increased. Nighttime and total daily food intakes were not significantly affected. 2) Short-term food intake suppression by intracerebroventricular rat IFN was accompanied by a small increase in cerebrospinal fluid and rectal temperatures. 3) Intracerebroventricular microinfusion of heat-treated rat IFN or of recombinant human interferon-alpha (rhIFN-alpha) did not affect food intake. Only one dose of rhIFN-gamma (400 ng/rat) decreased 2-h food intake. These results are consistent with the species specificity to the effects of IFNs. 4) Peripheral administration of rat IFN in doses equivalent to those administered centrally had no effect on food intake. The results suggest that IFN acts directly in the central nervous system to decrease short-term feeding.