Growth hormone and aging: Regulation, signal transduction and replacement therapy

It is widely accepted that during the aging process a number of alterations occur at the molecular cellular and tissue levels, ranging from an alteration in receptor signal transduction and gene expression to structural and morphological changes' in various tissues. There is abundant empirical and scientific evidence to support the hypothesis that many of these aging processes are closely related to a decline in hormone concentrations and/or hormone action but the etiology of these deficiencies remains elusive. GH and insulinlike growth factor-I (IGF-I) ave two potent anabolic hormones that decrease with age and appear to contribute to the loss of tissue function that is associated with normal aging. in this review age-related changes in the regulation of these hormones ave detailed as well as relatively new information on mechanisms of tissue resistance to GH. Finally, the potential use of GH as a therapeutic intervention to delay physiological changes associated with age is discussed.