n. a hormone secreted by the hypothalamus that inhibits the release of growth hormone (somatotropin) by the anterior pituitary gland. It is also secreted by cells in the islets of Langerhans in the pancreas, where it inhibits the secretion of insulin and glucagon. Analogues of somatostatin are used therapeutically in the control of acromegaly. Also called somatotropin-release inhibiting factor (SRIF).