Somatostatin is a hormone. Precisely it is mixture of two peptides, one built of 14 amino acids, the other of 28.
Somatostatin is secreted not only by cells of the hypothalamus but also by so called delta cells of stomach, intestine and pancreas. It binds to somatostatin receptors .
All actions of the hormone are inhibitory.
Somatostatin's main actions are:
- inhibits the release of growth hormone (GH)
- inhibits the release of thyroid stimulating hormone (TSH)
- suppresses the release of gastrointestinal hormones
- prolongs gastric emptying, gall bladder contraction and intestinal motility
- suppresses the release of pancreatic hormones
- suppresses the exocrine secretory action of pancreas
Octreotide (brand name Sandostatin, Novartis Pharmaceuticals) is an octopeptide that mimics natural somatostatin pharmacologically, though is a more potent inhibitor of growth hormone, glucagon, and insulin than the natural hormone. The FDA has approved the usage of a salt form of this peptide, octreotide acetate, as an injectable depot formulation for the treatment of acromegaly, the treatment of diarrhea and flushing episodes associated with carcinoid syndrome , and treatment of diarrhea in patients with vasoactive intestinal peptide-secreting tumors (VIPomas ). Octreotide has also been used off-label for the treatment of severe, refractory diarrhea from other causes.