Gastrinrelated

Gastrin-related describes phenomena associated with gastrin, a peptide hormone produced by G cells in the antrum of the stomach and, to a lesser extent, in the proximal small intestine. Gastrin circulates in several forms, including gastrin-34 and gastrin-17, derived from the larger precursor progastrin. The major physiological actions are to stimulate gastric acid secretion and promote growth of the gastric mucosa.

Mechanism: Gastrin binds to the cholecystokinin B (CCK-B) receptor on enterochromaffin-like cells and, to a lesser extent, directly on parietal cells, leading to histamine release and acid secretion. It also stimulates pepsinogen release and mucosal growth.

Regulation: Acid in the stomach inhibits gastrin release (negative feedback). Vagal stimulation via gastrin-releasing peptide increases release. Somatostatin and secretin dampen gastrin release. Protein-rich meals and certain amino acids stimulate gastrin release.

Clinical relevance: Hypergastrinemia can arise from gastrin-secreting tumors (gastrinomas) causing Zollinger-Ellison syndrome, or from conditions with reduced acid such as chronic atrophic gastritis; low gastrin levels may occur with pH-independent mechanisms. Measurement of fasting serum gastrin aids in diagnostic evaluation of gastric acid disorders.

Receptor and processing notes: Gastrin is derived from a larger precursor, with post-translational processing producing active gastrin peptides; the CCK-B receptor mediates most actions. The term gastrin-related is used in broader contexts to refer to physiological or pathological processes involving gastrin, its receptors, or related regulatory peptides.