Alteration of Growth Hormone Secretion in Aging: Peripheral Effects
In humans and animals, the aging process is associated with major endocrine changes. The view that these changes are responsible for the aging of an organism is undoubtedly oversimplistic (1). However, strong evidence indicates that they participate in the progressive loss of important physiologic functions, such as reproduction, immune function, maintenance of somatic anabolism, thyroid function, and so forth (2). In this process, synthesis and secretion of pituitary hormones are differently affected (3), being either increased (prolactin) or decreased (gonadotropins and growth hormone). Among endocrine alterations that develop early in aging, the blunting of basal and stimulated growth hormone (GH) secretion has been extensively documented in human and animal models (4–9). Numerous experimental observations of the aging somatotropic axis by our laboratory and others support the view that these alterations originate at the level of GH regulatory factors. Some important mechanisms that lead to this impairment are reviewed in the first part of this chapter.
KeywordsPolypeptide Arginine Half Life Estradiol Prolactin
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