APStracts 2:0012R, 1995.

Modulation of feeding by [beta]2-microglobulin, a marker of immune activation. Plata-Salam[acute]an, Carlos R., Gayatri Sonti, and Jeffrey P. Borkoski. School of Life and Health Sciences, University of Delaware, Newark, Delaware 19716, U.S.A.

APStracts 2:0012R, 1995.

Increased levels of [beta]2-microglobulin (part of the class I major histocompatibility complex molecules) in body fluids are associated with activation of the immune system and pathophysiological processes. Various anorexigenic cytokines including interferon-_ and tumor necrosis factor- [alpha] induce the expression of class I molecules. Therefore, it is possible that [beta]2-microglobulin may participate in the feeding suppression induced by cytokines or may have direct effects on feeding. In the present study, the effects of [beta]2-microglobulin on the central regulation of feeding was investigated. Intracerebroventricular (ICV) microinfusion of [beta]2- microglobulin (0.01 to 5.0 [mu]g/rat) suppressed the nighttime food intake dose-dependently. The most effective dose of [beta]2-microglobulin, 5.0 [mu]g/rat, decreased nighttime feeding by 38% and total daily food intake by 28%. Computerized analysis of behavioral patterns demonstrated that [beta]2- microglobulin decreased meal size and meal frequency during the initial 4-h interval, but only meal size during the second 4-h interval following the ICV microinfusion of 5.0 [mu]g [beta]2 -microglobulin/rat; meal duration was not significantly affected in any interval. For the complete nighttime period, only meal size was significantly decreased. Cerebrospinal fluid-brain and rectal temperatures did not change significantly. ICV microinfusion of heat- treated [beta]2-microglobulin or intraperitoneal administration of [beta]2- microglobulin in doses equivalent to those administered centrally had no effect on food intake. The results suggest that [beta]2-microglobulin may act centrally to decrease feeding and this effect may participate in the anorexia frequently accompanying pathological processes.

Received 27 September 1994; accepted in final form 10 January 1995.
APS Manuscript Number R560-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative Comp.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.