Also known as growth hormone inhibiting hormone (GHIH),
a hormone, secreted by the hypothalamus,
which inhibits the release of growth
hormone (GH) and thyroid-stimulating
hormone (TSH) from the anterior pituitary
gland. The secretion of somatostatin is stimulated by various factors,
including very high blood glucose levels,
which result from the effect that growth hormone has on glucose metabolism.
It is also produced by the delta (D) cells of the islets
of Langerhans in the pancreas and can
inhibit the release of glucagon and insulin
from the islets. Additionally, somatostatin inhibits the release of gastrointestinal
hormones, thereby lowering the rate of gastric emptying and reducing smooth
muscle contractions and blood flow within the intestine.
A molecule of somatostatin comprises two peptides,
one built of 14 amino acids, the other of
28 amino acids.