Role of inhibitory mechanisms in physiological regulation of lipogenesis

¹ Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts

The significance of inhibitory mechanisms in the regulation of hepatic lipogenesis was investigated by utilizing the "cold-fasted" state to evaluate their quantitative importance. Lipogenic inhibitory mechanisms, located primarily in the microsomes, appear in the liver of the rat during 24-hr fast at 0–2 C. Because the fatty acid synthesizing enzymes are found to be present at not markedly reduced levels and since the reduction in levels of coenzymes and stimulators of lipogenesis, such as lipogenin, can account for only part of the depression in lipogenesis, it is evident that inhibitory mechanisms play a major role in restricting hepatic lipogenesis in that condition. The general role of inhibitory mechanisms in the homeostatic regulation of lipogenesis is discussed.