The GHRP complex of peptides is naturally derived from the hypothalamus and pituitary glands. These naturally work to release growth hormone in the body or a specific G protein coupled receptor. GHRP-2 is a synthesized version of this chemical which has been developed to study the effects of these chemicals on animal tissues, and to stimulate growth hormone during research studies.
GHRP-2 can be administered to an animal to stimulate the release of this chemical from the pituitary gland. Daily administration will be necessary in order to achieve effects with this type of study. The application of synthetic GHRP-2 will increase the level of similar peptides– including those of the IGF series in animals.
It may also stimulate the pituitary gland of the animal, to secrete natural versions of this chemical or growth hormone. Some have also noted an increase in hypothalamus activity when GHRP-2 administrations were applied to animals.
In order to better understand the effects of obestatin on the secretion of pituitary hormone secretions, this peptide was administered to anesthetized male rats.
This peptide was administered intravenously, which did not seem to affect GH, PRL, ACTH or TSH levels.
Obestatin is believed to have opposing effects on gastric emptying, food intake, GH suppressive effect or intestinal contractility. This is the opposite reaction animals normally show when exposed to ghrelin.
GHRP-2 and GHRH were applied to the rats to act as a ghrelin receptor ligand to elevate growth hormone.
Obestatin did not appear to affect GHRP2 or GHGH induced growth hormone increases. The intracerebroventricular administration of obestatin continued to avoid raising TSH, GH, PRL and ACTH levels in the rat’s body. These findings suggest that obestatin does not affect secretions from the pituitary gland.
Expression in Muscle Proteolysis
Thermal injuries can lead to hypermetabolism which causes animals to lose skeletal muscle and body weight.
In previous studies it was demonstrated that injecting rats with ghrelin could stimulate the release of growth hormone and stimulate food intake to inhibit muscle proteolysis in rats that had a thermal injury.
To expand on these results, hexapeptide was used to mimic ghrelin as well as GHRP-2 to see the effects of these chemicals on E3 ubiquitin ligases and the breakdown of muscle protein in injured rats.
GHRP-2 was released slowly in vivo using a minipump for 24 hours and the mRNA expression for the thermal injury was measured for E3 ubiquitin and IL-6 expression.
Burn induced injuries increased the total myofibrillar protein breakdown form the EDL muscle in rats. This was attenuated by the presence of GHRP-2. Findings indicated that thermal injuries can be attenuated by administering GHRP-2.
Preventing Arthritis Induced E3 Uiquitin Enzyme Increases
Chronic arthritis can inhibit the function of the IGF system, causing a decrease in body weight while cachexia and muscular wasting can lead to protein degradation of the ubiquitin proteasome pathway.
GHRP-2 was administered in rats with arthritis for eight days in the liver and cardiac muscle.
This was found to decrease the IGF-1 mRNA controls but would not modify muscular IGF-1 genes.
This data indicates that increasing the activity of ubiquitin proteasome proteolytic pathways can be prevented by applying GHRP-2. Parallel changes to the TNF-a genes and IGFBP-5 with the ubiquitin ligases indicates that these are capable of participating in skeletal muscle alterations which are present during chronic arthritis.
GHRP-2 is not designed to act as a replacement for growth hormone, but instead it can be used to naturally stimulate the presence of growth hormone. This chemical can be applied via injection, but some animals have seen negative side effects when this chemical has been used in other forms.