The Role of Growth Hormone in the Regulation of Protein Metabolism with Particular Reference to Conditions of Fasting

Abstract

Growth hormone (GH) has potent protein anabolic actions, as evidenced by a significant decrease in lean body mass and muscle mass in chronic GH deficiency, and vice versa in patients with acromegaly. Depending on the prevailing physiological conditions and on which tissues and which proteins are under examination, the mechanisms involved include both stimulation of protein synthesis and restriction of protein breakdown. Apart from the possible direct effects of GH on protein dynamics, a number of additional anabolic agents, such as insulin, insulin-like growth factor-I and free fatty acids (FFA), are activated. Some of the most recent studies in the field have demonstrated a decisive role of stimulation of lipolysis and high circulating levels of FFA in orchestrating the maintenance of the protein pool of the body.