Modulation of feeding by beta 2-microglobulin, a marker of immune activation.
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-gamma 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 were investigated. Intracerebroventricular (ICV) microinfusion of beta 2-microglobulin (0.01-5.0 micrograms/rat) suppressed the nighttime food intake dose dependently. The most effective dose of beta 2-microglobulin, 5.0 micrograms/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 decreased only meal size during the second 4-h interval after the ICV microinfusion of 5.0 micrograms 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.
Plata-Salamán
C R
CR
School of Life and Health Sciences, University of Delaware, Newark 19716, USA.
Sonti
G
G
Borkoski
J P
JP
D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects; D001921:Brain; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D004327:Drinking Behavior / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects*; D007263:Infusions, Parenteral; D007274:Injections, Intraperitoneal; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012007:Rectum; D012016:Reference Values; D013997:Time Factors; D001613:beta 2-Microglobulin / Q000008:administration & dosage / Q000494:pharmacology*
D001613:beta 2-Microglobulin