Gastrin secretion is stimulated by the presence of amino acids in the gastric antrum and upper small intestine, by local distension of the gastric antrum, and by increased vagal activity. Calcium, administered orally or intravenously, and intravenous infusions of adrenaline also stimulate gastrin release. A gastric pH of less than 3 inhibits antral gastrin secretion; this negative feedback effect prevents the excess secretion of gastric acid. Somatostatin, a peptide present in endocrine cells in the stomach, and peptides of the secretin family, can reduce gastrin release.
