ABSTRACT
Growth hormone (GH) is a 191 amino acid, singlechain peptide synthesized in the somatotropic cells of the anterior pituitary gland and is often referred to as the ‘master anabolic hormone.’ Its biologic activity is mediated through signal transduction of a ubiquitous GH-specific transmembrane receptor. Additional effects are mediated through insulin-like growth factor 1 (IGF-1; known as the ‘second message’ of GH) that is synthesized largely in the liver and most other tissues. During the human aging process, daily secretion and integrated plasma concentrations of GH decrease as do IGF-1 levels.
