Somatostatin-14 (ST-14)

Somatostatin-14 (SST-14) is a short, cyclic peptide hormone and neuropeptide, composed of 14 amino acids, that acts as a potent and ubiquitous inhibitory regulator in the body. It exists alongside a slightly longer 28-amino-acid form (Somatostatin-28), both derived from the same precursor protein, somatostatin. Its main physiological role is to function as a crucial endocrine and paracrine "brake." In the endocrine system, it potently inhibits the secretion of key hormones: growth hormone from the anterior pituitary gland and thyrotropin (TSH). Within the digestive system, it acts locally to suppress a wide array of processes, including the secretion of insulin and glucagon from the pancreas, as well as gastrin, gastric acid, and other exocrine digestive juices, thereby slowing gastrointestinal motility and nutrient absorption.

Somatostatin-14 exerts its effects by binding to specific G protein-coupled receptors (SSTR1-5), which are widely distributed in target tissues. Activation of these receptors leads to the inhibition of adenylate cyclase, reduced calcium influx, and activation of potassium channels, collectively dampening cellular excitability and secretory activity.

Due to its broad inhibitory profile, synthetic analogs of somatostatin, like octreotide and lanreotide, are invaluable in clinical medicine. They are primarily used to treat neuroendocrine tumors by suppressing pathological hormone overproduction, and to manage conditions involving severe gastrointestinal hypersecretion.