Regulation of Adipsin and Body Composition in the Monosodium Glutamate (MSG)-Treated Mouse

Changes in food intake, serum adipsin, and obesity were evaluated in the MSG-treated mouse. In Experiment 1, mice treated with MSG had 50% lower serum adipsin and over 2-fold higher percentage of body fat than the lean controls. Both feeding caffeine and restricting intake normalized serum adipsin and caused weight loss, but did not normalize the percentage of body fat. No additional effect was gained by feeding isoproterenol or ephedrine in combination with caffeine. In Experiment 2, we separated the direct effect of caffeine from the associated depression in intake using a paired feeding design, and also determined the effects of selected adrenergic agents and somatotropin (S). Somatotropin increased weight gain and reduced the percentage of body fat in healthy and obese mice, and tended to lower serum adipsin. Caffeine clearly depressed intake, caused weight loss, and increased serum adipsin, but similar results were achieved by restricting intake. None of the adrenergic drugs tested changed serum adipsin. Ephedrine depressed food intake and caused weight loss, but reduced the percentage of body fat only at the highest dietary concentration (2000 mg per kg of diet). Phenylephrine reduced weight gain without a concomitant effect on the percentage of body fat, and isoproterenol did not influence weight gain or body fat.