Study: IGF and insulin

Feb. 15, 2011 - PRLog -- Scientists who conducted laboratory studies of ST, highlighted the fact that it is effective only when administered in a living organism. When added to the culture of muscle cells with growth hormone in general no action is rendered even if the cells were in an environment with sufficient energy and plastic material. It was found that growth hormone itself directly to the cells has no effect. Back in the late 50 - ies, it was assumed that there is any - is the mediator of hormonal signals between the STG and the cells of the body. In the early 70's - years was found a group of mediators. They were called "somatomedins. In further studies have been described: somatomedin A, somatomedin B, and somatomedin C. They were also the name of insulin growth factor (IGF, or in English literature - IGF). Somatomedin C was called IGF - 1, somatomedin B called IGF - 2 and somatomedin A was called IGF - 3. In the 80 - years, but it turned out that in fact there is only one only IGF - 1 http://www.buyhghsupplement.info/2008/02/igf-for-antiaging-1975.html . Other somatomedins were experimental artifacts.
These substances are peptides (molecules they are composed of several chemically related amino acids) and bind to plasma proteins, called the "carrier of growth factors. Media allows growth factors to maintain activity for much longer (several hours against 20-30 minutes for free-form).
For many years, scientists believed growth factor product glands because of the appearance of his indispensable in growing bodies. In fact, from the liver it enters the bloodstream and then carried by special carrier proteins in organs and tissues. There, in the presence of sufficient nutrients and load (for the muscle cell) growth factor stimulates the development of muscle, bone and connective tissue. This old theory is, in many cases confirmed by recent data. Found that growth factor 1 is synthesized in many tissues (ie, it is not only endocrine but also autocrine factor). Every cell in the body may, if necessary itself to provide itself with this substance, in addition to coming from outside.
Incidentally, in the synthesis of IGF-1 plays an important role insulin. Without it, the liver does not receive the necessary amino acids and will not start the mechanism of synthesis of growth factors tissues.
Number of IGF-1 also depends on the person's age (small at early childhood, reaches a peak by the end of the transitional period and decreases after 50). Because of the presence of the carrier protein concentration of IGF-1 during the day remained relatively constant, whereas the concentration of growth hormone varies.

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