CORTISOL STIMULATION OF GLYCOGEN SYNTHESIS IN FASTED RATS1

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Abstract
The acute effects of cortisol that result in an increase in liver glycogen deposition were studied in fasted rats, using C14O2 and glucose-6-C14 as labeled substrates. The incorporation of labeled carbon into blood glucose, liver glycogen and liver dicarboxylic acids was determined. The results of these experiments indicate that cortisol increases the incorporation of label from radioactive bicarbonate into liver glycogen without any significant increase in the activity of either blood glucose or liver dicarboxylic acids. Studies with labeled glucose showed increased deposition of glycogen from this substrate. There was little recycling of C14 from glucose via the Cori cycle. Under these conditions cortisol did not appear to increase hepatic glucose production as measured by changes in specific activity of blood glucose. Evidence is presented that in the fasting adrenalectomized animal there is some specific impairment in glycogen formation apart from the ability of the liver to form glucose. It is suggested that the adrenal cortical steroids may act to increase glycogen deposition from blood glucose.