The glucose effect and cortisone action upon rat liver and muscle protein metabolism

Abstract

Cortisone administration to fasted rats led, 5 hr later, to a 43% decrease of the incorporation of radioactive leucine into total muscular proteins, with little modification of total liver protein labeling. At the same time period, the accumulation of labeled α-aminoisobutyric acid (AIB) was increased into the liver and slightly decreased into the muscle. When administered prior to the steroid injection, glucose completely inhibited the hormonal effect on muscle protein labeling. It increased the AIB accumulation in muscle and diminished it in the liver, but did not prevent the changes on these parameters brought about by cortisone. The effect of the glucose administration did not appear to be due to an impaired radioactive Cortisol metabolism in the liver or muscle. The data suggest that the cortisone effect on muscular protein labeling may be independent of amino-acid penetration as reflected by AIB distribution. The discrepant effects of the hormone in starved vs glucose loaded rats suggest that part of the cortisol response of the body is modulated by its nutritional state.