Somatopause

Gender markedly influences GH secretion in young adults. Premenopausal women exhibit a two-fold less rapid decline than men in daily GH production with increasing age. Young women also manifest less vulnerability to the suppressive effects of increased total body fat and reduced physical fitness on GH secretion [19].An important ongoing clinical issue relates to the uncertain role of sex-hormone deficiency in the aging-related impoverishment of GH and IGF-I production in both women and men [20]. Preliminary data from clinical studies raise the possibility that combined GH and androgen repletion in older men can have an additive effect on increasing muscle mass [19].

Levels of the nutritional signaling peptide leptin, mostly produced in white adipose tissue, conveys signals to the hypothalamus about fat stores and, in response, hypothalamic efferents regulate food intake and energy expenditure. Leptin inhibits the hypothalamic release of the orexigenic (appetite-inducing) peptide neuropeptide Y (NPY) and activates the sympathetic nervous system. The latter stimulates lipolysis in adipose tissue via the beta-3 adrenergic receptor, cAMP accumulation, and increased activity of mitochondrial uncoupling protein (UCP)-3, thus generating heat (which is dissipated) rather than ATP (which is stored). Leptin- receptor signaling may be attenuated in aging [21].

The aging process causes certain areas of the face to undergo fat atrophy while others experience a persistence or hypertrophy of fat. Fat atrophy occurs in the periorbital, forehead, buccal, temporal, and perioral areas. Fat hypertrophy, however, is seen submentally, in the jowl, lateral nasolabial fold, lateral labiomental crease, and lateral malar areas. The suborbital area may display atrophic changes with concavities and evidence of the underlying orbital rim or hypertrophy with infraorbital fat accumulation and festooning [22].