Growth hormone (GH) is a peptide having 191 amino acids which stimulates the production of numerous different growth factors, e.g. insulin-like growth factor I (IGF-I) and so promotes growth of numerous tissues (skeleton, connective tissue, muscle and viscera) and physiological activities (raising nucleic acid and protein synthesis and lipolysis, but lowering urea secretion). Human growth hormone (HGH) is the most abundant hormone secreted by the anterior pituitary gland and has significant anabolic and anti-catabolic effects on the body. Cells of the immune system, such as macrophages and lymphocytes also produce and secrete growth hormone. Growth hormone stimulates the liver to produce somatomedins which, in turn, promote bone, muscle, cartilage, kidney, liver and skin growth. There're definite side effects from taking hGH if taken in excess or if not carefully monitored. The side effects of recombinant HGH therapy are well documented. Possible side effects associated with HGH injections or synthenic replacement include water etention, the development of antibodies to HGH, insulin resistance and diabetes, hypertension, carpal tunel syndrome, abnormonal bone growth, reduced life span, disturbed insulin metabolism, leukemia, overgrowth of connective tissue, and tumors, etc. The elevation of growth hormone levels in humans, upon administration of GH-releasing compounds can lead to enhanced body weight and to enhanced milk production if sufficiently elevated GH levels occur upon administration. Administration of higher than physiological concentrations of HGH produce serious side effects, including tissue turgor, neuropathy, back pain, increase in liver enzymes aspartate aminotransferase (SGOT) and alanine aminotransferase SPGT, increased sweating, headache, skin and joint problems, hypertension, and edema.
Growth hormone is synthesized and secreted by the somatotrophic and somatomammotrophic cells of the lateral anterior pituitary. The control of GH production and secretion is complex, but is mainly under the influence of growth hormone releasing hormone (GHRH) and somatostatin, which stimulate and inhibit it, respectively. In response to the injection of a synthenic growth hormone the hypothalamus triggers elevated levels of somatostatin, a growth hormone release inhibitor, which then prompts the pituitary gland of the subject individual to curb the release of its naturally produced growth hormone. Of course, it is undesirable to inhibit the natural release of the growth hormone from the pituitary gland in favor of the synthetic hormone. More particularly, the release of natural growth hormone from the pituitary gland is controlled by negative feedback involving growth hormone releasing and release inhibiting factors. If GH levels are low, the pituitary gland is stimulated by releasing factors in the hypothalamus to increase the release of natural growth hormone. If GH levels are high, the pituitary gland is inhibited from releasing natural growth hormone by the release inhibiting factor, somatostatin, from the hypothalamus. Thus any addition of growth hormone to the human system, whether natural or synthetic, will impact this negative feedback loop, thereby disrupting the balance of growth hormone levels achieved by the tandem operation of hypothalamus and pituitary gland. As a result, the pituitary gland may slow down or even cease production and release of the natural growth hormone, and the normal function of the pituitary gland of the subject is disrupted.
Chronic elevation of growth hormone levels in humans usually results in either gigantism or acromegaly, in which excessive levels of GH are present. The development of myopathy in acromegaly patients has led to hypertrophy overshadowed by pathology. The abnormally enlarged facial and extremity bones of this disease can be treated by administering a GH-RH antagonist. Growth hormone, besides affecting skeletal growth, can also influence other organ systems, in particular, the liver and kidney. In the kidney, it has been associated with glomerulosclerosis and nephropathy. The damage to the retina and kidneys respectively in these diseases, believed to be due to growth hormone, results in blindness or reduction in kidney function. This damage can be prevented or slowed by administration of an effective GH-RH antagonist. In the liver, it has been shown to cause an increase in liver size, as a consequence of both hyperplasia and hepatocyte hypertrophy. The hepatocellular lesions associated with high growth hormone levels progress with age. An incrase of blood size can lead to hypertension, which also places stress on the heart due to increased blood viscosity or thickening. It has been reported that patients taking synthetic growth hormone develop antibodies resistant to. These antibodies not onlypose a health threat to the body's own supply of growth hormone, but normal immune function as well. |
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