Gastrina

Gastrin, also called gastrin in some languages (gastrina), is a peptide hormone produced mainly by G cells in the lining of the stomach, particularly in the antrum, with smaller amounts secreted in the duodenum. It exists in several related forms, including gastrin-17 (G-17) and gastrin-34 (G-34), derived from a precursor molecule called preprogastrin. G-34 is the major circulating form, while G-17 is predominant in the stomach.

Gastrin's primary physiological role is to stimulate gastric acid secretion. It acts on receptors of the parietal cells directly and indirectly by promoting the release of histamine from enterochromaffin-like (ECL) cells, which then enhances acid production. Gastrin also has trophic, or growth-promoting, effects on the gastric mucosa, contributing to the maintenance and growth of the stomach lining.

Secretion of gastrin is triggered by the presence of peptides and amino acids in the stomach, stomach distension, and vagal stimulation via gastrin-releasing peptide. Its release is negatively regulated by gastric acidity; somatostatin from D cells inhibits gastrin secretion as part of a negative feedback loop.

Clinically, excess gastrin secretion is seen in gastrin-secreting tumors called gastrinomas, which can cause Zollinger-Ellison syndrome characterized by gastric acid hypersecretion and peptic ulcers. Diagnosis often involves measuring serum gastrin levels and provocative tests, such as the secretin stimulation test, to differentiate gastrinoma from other causes of hypergastrinemia.