(which respond to Ach). Respectively, these receptors will increase somatostatin output and decrease somatostatin output from the ?-cells. VIP, vasoactive intestinal peptide, acts positively on ?-cells resulting in more somatostatin being released.

In the stomach, somatostatin acts directly on the acid-producing parietal cells via a G-protein coupled receptor (which inhibits adenylate cyclase, thus effectively