Growth hormones

November 12, 2012

Growth hormones

Growth hormone is produced in the anterior pituitary gland; it is a protein hormone consisting of around 190 amino acids. Growth hormones contribute to several physiological processes including growth and metabolism. The effects of growth hormone may be direct or indirect.

  • Direct effects – occur as a result of the growth hormone binding its receptor on target cells.

  • Indirect effects are the result of a hormonal response to growth hormone.

Growth hormone is responsible for stimulating body growth by stimulating the liver and other tissues to secrete IGF-I, it also contributes to bone growth as a result of the proliferation of chondrocytes.

Growth hormone also appears to be the main contributor to muscle growth, stimulating amino acid uptake and protein synthesis n both muscle and other tissues.

In some cases it has been clearly shown that growth hormone has a direct effect on metabolism, in others that the mediator IGF-I is present and in yet others that both direct and indirect effects are involved.

  • Protein metabolism – generally protein anabolism is stimulated by growth hormone. Effects noted included increased amino acid uptake and protein synthesis and decreased oxidation of protein.

  • Fat metabolism -growth hormone stimulates the breakdown of triglycerides.

  • Carbohydrate metabolism – growth hormone helps to keep blood glucose levels within the normal range.

Growth hormone secretion is generally controlled by several hormones although it may also be affected by exercise, sleep, nutrition and even stress.

Growth hormone disorders

  • Growth hormone deficiency – will manifest with growth retardation or dwarfism and may be the result of a genetic disorder or an acquired disease.

  • Excessive growth hormone secretion, a very rare disorder, may result in giantism should it occur in young children or teenagers. If there is excessive secretion of the growth hormones in adults it may result benign pituitary tumors giving rise to acromegaly – the clinical signs for this disorder include overgrowth of the extremities as well as cardiac disease and abnormalities of the jaw.

Wider practical uses of growth hormones

Recent advances in technology mean that there is now an almost unlimited supply of growth hormone which is produced using recombinant DNA this has led to a number of applications for both humans and animals and is subject to ongoing research.

  • Children who are pathologically short in stature are generally treated with human growth hormone.

  • Growth hormone has been used in an attempt to improve athletic performance.

  • Research is ongoing into the role of growth hormone in the aging process.

  • Growth hormone is used to increase milk production in the dairy industry.

  • Treatment of growing pigs with porcine growth hormone has been shown to increase muscle growth and reduce fat deposits.

  • Growth hormones are an essential part of the body’s metabolic function, its’ function and effects are the subject of much ongoing research which it is hoped will lead to further positive developments for its use.

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