Growth hormone releasing peptides (GHRP) are synthesized in the laboratory to mimic the function of growth hormone. They are not found naturally occurring and come in more than one form. Two of these forms are GHRP 2 and GHRP 6. While they both known as GH Secretagogues and allow for the release of growth hormone from the pituitary gland and the hypothalamus, their functions and side effects are not exactly the same. They work by activating a protein receptor. It is important to note that GHRPs are in no way structurally similar to the naturally occurring growth hormone releasing hormones.
The first of its kind, GHRP 6 is a laboratory synthesized peptide to aid in the release of growth hormone. In animal test subjects it was found to be useful in treating obesity and other eating disorders. However, due to it being the first generation peptide some problems did arise, as it had some unwanted effects like increasing hunger
It works as an appetite stimulant by increasing ghrelin. Ghrelin is a peptide that is found in the cells of the stomach. It works by binding to receptors to send a single to the brain when the stomach is empty, causing hunger.
The second generation of growth hormone releasing peptides was created, this one being called GHRP 2. What makes it different than GHRP 6 is it allows for a maximum release of GH over a longer period of time. It also has been shown to have less negative side effects than its predecessor.
It has been seen in test animals to work by stimulating the pituitary glands to release growth hormone. It works in two ways. First, it works by increasing the signal to release growth hormone to increase their levels. Then it inhibits somatostatin, to also help increase the growth hormone levels.