VIVO Pathophysiology Show
Growth hormone is a protein hormone of about 190 amino acids that is synthesized and secreted by cells called somatotrophs in the anterior pituitary. It is a major participant in control of several complex physiologic processes, including growth and metabolism. Growth hormone is also of considerable interest as a drug used in both humans and animals. Physiologic Effects of Growth HormoneA critical concept in understanding growth hormone activity is that it has two distinct types of effects:
Keeping this distinction in mind, we can discuss two major roles of growth hormone and its minion IGF-I in physiology. Effects on Growth Growth is a very complex process, and requires the coordinated action of several hormones. The major role of growth hormone in stimulating body growth is to stimulate the liver and other tissues to secrete IGF-I. IGF-I stimulates proliferation of chondrocytes (cartilage cells), resulting in bone growth. Growth hormone does seem to have a direct effect on bone growth in stimulating differentiation of chondrocytes. IGF-I also appears to be the key player in muscle growth. It stimulates both the differentiation and proliferation of myoblasts. It also stimulates amino acid uptake and protein synthesis in muscle and other tissues. Metabolic Effects Growth hormone has important effects on protein, lipid and carbohydrate metabolism. In some cases, a direct effect of growth hormone has been clearly demonstrated, in others, IGF-I is thought to be the critical mediator, and some cases it appears that both direct and indirect effects are at play.
Control of Growth Hormone SecretionProduction of growth hormone is modulated by many factors, including stress, exercise, nutrition, sleep and growth hormone itself. However, its primary controllers are two hypothalamic hormones and one hormone from the stomach:
Growth hormone secretion is also part of a negative feedback loop involving IGF-I. High blood levels of IGF-I lead to decreased secretion of growth hormone not only by directly suppressing the somatotroph, but by stimulating release of somatostatin from the hypothalamus. Growth hormone also feeds back to inhibit GHRH secretion and probably has a direct (autocrine) inhibitory effect on secretion from the somatotroph. Integration of all the factors that affect growth hormone synthesis and secretion lead to a pulsatile pattern of release. Basal concentrations of growth hormone in blood are very low. In children and young adults, the most intense period of growth hormone release is shortly after the onset of deep sleep. Disease StatesStates of both growth hormone deficiency and excess provide very visible testaments to the role of this hormone in normal physiology. Such disorders can reflect lesions in either the hypothalamus, the pituitary or in target cells. A deficiency state can result not only from a deficiency in production of the hormone, but in the target cell's response to the hormone. Clinically, deficiency in growth hormone or defects in its binding to receptor are seen as growth retardation or dwarfism. The manifestation of growth hormone deficiency depends upon the age of onset of the disorder and can result from either heritable or acquired disease. The effect of excessive secretion of growth hormone is also very dependent on the age of onset and is seen as two distinctive disorders:
Pharmaceutical and Biotechnological Uses of Growth HormoneIn years past, growth hormone purified from human cadaver pituitaries was used to treat children with severe growth retardation. More recently, the virtually unlimited supply of growth hormone produced using recombinant DNA technology has lead to several other applications to human and animal populations. Human growth hormone is commonly used to treat children of pathologically short stature. There is concern that this practice will be extended to treatment of essentially normal children - so called "enhancement therapy" or growth hormone on demand. Similarly, growth hormone has been used by some to enhance atheletic performance. Although growth hormone therapy is generally safe, it is not as safe as no therapy and does entail unpredictable health risks. Parents that request growth hormone therapy for children of essentially-normal stature are clearly misguided. The role of growth hormone in normal aging remains poorly understood, but some of the cosmetic symptoms of aging appear to be amenable to growth hormone therapy. This is an active area of research, and additional information and recommendations about risks and benefits will undoubtedly surface in the near future. Growth hormone is currently approved and marketed for enhancing milk production in dairy cattle. There is no doubt that administration of bovine somatotropin to lactating cows results in increased milk yield, and, depending on the way the cows are managed, can be an economically-viable therapy. However, this treatment engenders abundant controversy, even among dairy farmers. One thing that appears clear is that drinking milk from cattle treated with bovine growth hormone does not pose a risk to human health. Another application of growth hormone in animal agriculture is treatment of growing pigs with porcine growth hormone. Such treatment has been demonstrated to significantly stimulate muscle growth and reduce deposition of fat. Advanced and Supplemental Topics
Updated 2021. Send comments to A Bosnian translation of this page by Amina Dugalic is available at Bosnian Translation A French translation of this page by Jean-Etienne Bergemer is available at French Translation An Italian translation of this page by Ahsan Soomro is available at Italian Translation A Slovenian translation of this page by Andrijana Savicević is available at Slovenian Translation A Ukrainian translation of this page by Olena Chervona is available at Ukrainian Translation Which hormone regulates the metabolism of carbohydrates fats and proteins in the body?Insulin is the key hormone of carbohydrate metabolism, it also influences the metabolism of fat and proteins. It lowers blood glucose by increasing glucose transport in muscle and adipose tissue and stimulates the synthesis of glycogen, fat, and protein.
Which hormone regulates the metabolism of carbohydrates fats and proteins in the body and also has an anti inflammatory action?Cortisol is known as a stress hormone involved in the response to physical and/or emotional stress. Cortisol also participates in various homeostatic maintenance actions: blood pressure; immune system; metabolism of protein, carbohydrate, and adipose; and anti-inflammatory action.
What is the hormone that regulates metabolism?Thyroid hormone (TH) regulates metabolic processes essential for normal growth and development as well as regulating metabolism in the adult (28, 40, 189). It is well established that thyroid hormone status correlates with body weight and energy expenditure (80, 127, 143).
What hormone regulates protein metabolism and growth?Insulin, GH and IGF-I play a dominant role in the day-to-day regulation of protein metabolism. In humans insulin appears to act primarily to inhibit proteolysis while GH stimulates protein synthesis.
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