Somatostatin is an inhibitor of hormone release and blocks the response to hormonal stimulation of the effector tissue. It inhibits a wide range of gastrointestinal functions (Fig. 19.7), the most clinically important being the inhibition of pancreatic secretions, gallbladder contraction, and insulin release. Somatostatin levels in plasma increase after food ingestion, with a more marked response seen with fat and protein than with carbohydrate, although the physiological importance of this response is unknown.
