Hormonal regulation of protein degradation in skeletal and cardiac muscle

A number of hormones produce either anabolic or catabolic effects on protein degradation in muscle. These effects can account for the changes in muscle proteolysis associated with a variety of physiological and pathological states. Thus the balance of hormones within the organism seems to play an important role in the overall regulation of this process. In the fed state, insulin may be the single most important factor maintaining low rates of proteolysis, whereas the catabolic effects of the glucocorticoid hormones in fasting seem to predominate. The proportions of these hormones may be important not only during starvation, but also in trauma and in diseases associated with their altered production and secretion (e.g., diabetes, Cushing's syndrome). Hyperthyroidism too causes catabolic effects on muscle proteolysis.