Somatostatin Acetate (also known as Growth Hormone Inhibitory Hormone (GHIH) or Growth Hormone Release Inhibitory Factor (SRIF)) or Growth Hormone Release Inhibitory Hormone is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation through interaction with G proteins. Couples somatostatin receptors and inhibits the release of many secondary hormones. Somatostatin regulates insulin and glucagon. Somatostatin acetate inhibits and stimulates the thyroid gland and secretes insulin and glucagon. Secretion can be inhibited by a test meal and five pentapeptide gastrin to stimulate gastric acid, pepsin and inhibit the release of gastrin.