Glucocorticoid control of the liver glycogen synthetase-activating system.

The activity of the enzyme system which converts hepatic glycogen synthetase to the active form disappears from the livers of fasted, adrenalectomized rats. The level of active synthetase in such preparations is nil. After the administration of glucocorticoid there is a return of activating enzyme activity and gradual increases in the level of active glycogen synthetase, the rate of glycogen synthesis, and the glycogen content of the liver. We propose that the changes in activating enzyme activity are the proximate cause of the changes in the level of active synthetase and the consequent alterations in hepatic glycogen content in response to the glucocorticoid state of the animal.