Glycogenolytic effect of cortisol previous to its interaction with the cell nucleus in mouse liver

Activities of hepatic glycogen synthase a and glycogen phosphorylase a have been studied in mouse liver at different times after an acute intraperitoneal administration of hydrocortisone. It has been observed an increase of glycogen synthase a activity and a decrease of glycogen phosphorylase a between 2 and 3.5 hours after cortisol injection. An early effect, previous to the synthase activation has been discovered. Cortisol caused an increase of glycogen phosphorylase a activity in mice 45 min after injection. This early effect of cortisol is independent of protein synthesis and it does not imply an increase in cAMP levels.