Somatostatin, also known as growth hormone inhibiting hormone, is an endogenous peptide hormone. Somatostatin has two active forms produced by the alternative cleavage of a single preproprotein, one consisting of 14 amino acids, the other consisting of 28 amino acids. Somatostin 14 is the shorter isoform and works primarily in the brain, while the 28 amino acid form acts in the GI tract. Somatostatin 14 regulates the endocrine system and affects neurotransmission and cell proliferation though interaction with G protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones.
