Since I just finished up my GH and IGF e-book, and the information is still fresh in my head, I'm going to give you guys a simple explanation of what Growth Hormone and Insulin Like Growth Factor are.
First, lets go over Human growth Hormone (GH), then we'll move onto IGF-1.
GH is produced in the body by the pituitary gland. This production is as a result of Growth Hormone Releasing Hormone (GHRH) being released by the hypothalamus.
You can influence this release by nutrition and exercise. You can also inject HGH, but that doesn't make your body release it, it simply adds it into your body.
Once it is released, GH stimulates the the body's cell to both increase in size and experience more rapid cell. It enhances the rapid movement of amino acids through cell membranes. It increases the rate which amino acids are used by cells and converted into proteins like those found in muscle tissue.
IGF1 is a polypeptide hormone about the same size as insulin, released primarily in the liver (but also in peripheral tissues, like muscle- forexample) with the stimulus of Growth Hormone (GH). Mechano Growth Factor is an isoform of IGF-1 (technically it is called IGF-1Ec) released by the muscle in response to mechanical work (like lifting weights). This isoform may be responsible largely for hypertrophy induced by IGF-1.
IGF-1, in general, is probably responsible for the anabolic activity of GH. This includes both nitrogen retention and protein synthesis, as well as muscle cell hyperplasia (increase in number of muscle cells), as well as mitogenesis (the growth of new muscle fibers).
Interestingly, IGF-1 can also cause skeletal muscle hypertrophy by activating the phosphatidylinositol 3-kinase (PI3K)-Akt pathway.
This givess us reason to think that IGF-1 probably acts on most tissues to enhance growth via several possibly disparate mechanisms.
Although GH and IGF-1 are inexorably connected, they actually produce a few divergent effects.
IGF is both a known neuroprotector and neuropromotor also. Clearly, this is because there are IGF receptors within the brain and in motor neurons. Interestingly, there is no IGF receptors in fat.
Igf, therefore- must be injected intramuscularly, while GH necessarily is injected subcutaneously.
Finally, IGF is vital to the proper production of connective tissue; and both endogenous and exogenous IGF improves collagen formation and aids in the repair of cartilage. IGF is also vital to proper bone density and bone density regulation, although only GH can actually be said to be responsible for the elongation of bone tissue.
The IGF-1 available on the Black Market right now is Lr3igf-1 (Long R3 Insulin-like Growth Factor-I or Long R3IGF-I). This is simply an 83 amino acid analog of human IGF-I comprising the complete human IGF-I sequence with the substitution of an Arg for the Glu at position 3 and a 13 amino acid extension peptide at the N-terminus.