Somatostatin, also known as growth hormone-inhibiting hormone, is a naturally-occurring peptide hormone of 14 or 28 amino acid residues that regulates the endocrine system. It is secreted by the D cells of the islets to inhibit the release of insulin and glucagon, and is also generated in the hypothalamus, where it inhibits the release of growth hormone and thyroid-stimulating hormones from the anterior pituitary.Somatostatin is a tetradecapeptide which can suppress the growth hormone (GH) secretion and control the pituitary hormone secretion in human CNS.

Glc(a1-6)Glc(b)-O-Ph(4-Ac)

Reserpin N-oxide shows half the activity of Reserpine.