somatóstatin

Somatostatin, also known as growth hormone-inhibiting hormone (GHIH), is a peptide hormone that acts both as a hormone and a neurotransmitter. It is produced by several tissues in the body, including the hypothalamus, pancreas, and gastrointestinal tract. In the hypothalamus, somatostatin plays a crucial role in regulating the release of pituitary hormones, particularly growth hormone and thyroid-stimulating hormone. It inhibits the secretion of these hormones, thus playing a key role in growth and metabolism.

In the pancreas, somatostatin is produced by delta cells in the islets of Langerhans. Here, it acts locally to inhibit the release of insulin and glucagon, thereby modulating blood glucose levels. This paracrine effect helps to fine-tune the balance between glucose production and utilization. In the gastrointestinal tract, somatostatin is found in D cells of the stomach, small intestine, and pancreas. It inhibits the secretion of various gastrointestinal hormones, including gastrin, secretin, and cholecystokinin, as well as reducing gastric acid secretion, intestinal motility, and blood flow to the gut.

The effects of somatostatin are mediated through its binding to specific somatostatin receptors, of which there are five known subtypes (SSTR1-5). These receptors are widely distributed throughout the body, explaining the diverse actions of somatostatin. Due to its inhibitory actions on a wide range of physiological processes, somatostatin has therapeutic applications, particularly in the management of conditions involving excessive hormone secretion, such as acromegaly, carcinoid syndrome, and certain gastrointestinal tumors. Synthetic analogs of somatostatin, such as octreotide and lanreotide, are commonly used for these purposes.