GLOSSARY

Somatostatin (growth hormone-inhibiting hormone, GHIH) is a peptide in 14- and 28-amino-acid forms secreted by the hypothalamus, pancreatic delta cells, gastric and intestinal D cells, and the nervous system; it is the body’s “universal inhibitor”.

Inhibitory Effects

• Pituitary: inhibits growth hormone and TSH.
• Pancreas: inhibits insulin, glucagon, and exocrine secretions (a paracrine effect in the islets).
• Gut: inhibits gastrin, gastric acid, CCK, secretin, gut motility, and absorption.
• Reduces splanchnic blood flow.

Characteristics

• Very short half-life: about 1–3 minutes.
• Receptors: five types, SSTR1–SSTR5 (Gi-coupled GPCRs; lower cAMP).

Clinical Application