Somatostatin (also known as growth hormone inhibiting hormone (GHIH) or somatotropin release-inhibiting factor (SRIF) is widely distributed throughout the body. It has two active forms produced by alternative cleavage of a single preproprotein: one of 14 amino acids, the other of 28 amino acids. Somatostatin is an important regulator of endocrine and nervous system function. It exerts its biologic actions by binding to specific high affinity receptors on the cell surface. Somatostatin has also been shown in sympathetic nerves, mucosal cells, myenteric nerves of the gastrointestinal tract, salivary glands and in some parafollicular cells of the thyroid.