Normally, levels of GHRH, growth hormone, somatostatin, and IGF-1 are tightly controlled by each other in a natural “feedback loop.” This feedback loop regulates supply of these hormones in the body. For example, a high level of IGF-1 in the blood suppresses secretion of GHRH and growth hormone in healthy people. Now, hopefully you know that the suppression of GHRH and HGH is due to somatostatin which is secreted by your hypothalamus. As stated above soma is excreted when excess IGF, and HGH levels are elevated above the body's own natural production. In someone who is a couch potato that's good for them, it helps prevent Acromegaly. With us bodybuilders, that's not good. There is a class of compounds called Acetylcholineesterase inhibitors, that inihibit acetylcholineesterase, which is responsible for deactivating acetylcholine in the brain. Guess what? Acetylcholine is a very effective inhibitor of Somatostatin. Therefore Acetylcholineesterase inhibitors are indirect somatostatin inihibitors, working by increasing acetylcholine levels which then inhibit somatostatin levels. We need to suppress the somatostatin when we elevate IGF. That may be a reason people do not get great results on IGF alone or not using it in conjunction with a somatostatin inhibitor, such as Pyrostigmine (120mg/ed) Galantamine (8-16mg/ed) Huperzine A (50-150mcg/ed).

http://www.emedicinehealth.com/script/main/mobileart-emh.asp?articlekey=...

(Oh, and if you need a reason NOT to go guns a blazing and mess around injecting high levels of IGF, of course hypothetically, keep reading into the link above.)

Also, vitamin D has been shown to increase circulating IGF-1 and IGF binding proteins (IGFBP-3), while suppressing parathyroid hormone. Meaning the body can uptake more IGF and not waste it by increasing the amount of binding proteins and decrease the absorption of excess calcium in the kidneys (cause kidney stones) and decrease IGF absorption into the the intestines (function of the parathyroid hormone). Also, IGF is known to be the central system for expanding tumors and cancer, (this includes gynomastia), due to its hyperplasia effects. However, with the use of vitamin D it has been shown to decrease it's ability to stimulate any cell hyperplasia in cancerous or tumerous cells.

Diego Ferone, PhD, of the University of Genova in Italy, and colleagues.

http://www.medpagetoday.com/Endocrinology/GeneralEndocrinology/40932

So to put in summation, if you are on HGH, GHRP or just IGF, you will secrete somatostatin because your body doesn't like the over production, much like estrogen when on AAS. Many may not have been getting the best results possible due to this. Adding a soma inhibitor alongside a HGH or Peptide cycle may provide very beneficial results. (I'd be cautious if using it with CJC with DAC, you don't want continuous production of HGH 24/7). Also, adding vitamin d to your regime will allow more uptake of IGF, decrease uptake in intestines, and reduced stimulation towards tumorous cells (gyno).