Histomorphological characteristics of gastric mucosa in patients with Zollinger-Ellison syndrome or autoimmune gastric atrophy: role of gastrin and atrophying gastritis.

The role of gastrin in the pathophysiology of two diseases affecting the human stomach, the Zollinger Ellison syndrome (ZES) and the pernicious anemia (PA), is reviewed. Both diseases present chronic hypergastrinemia but from different origins. The ZES is characterized by the occurrence of ectopic endocrine gastrin-secreting tumors and PA by a fundic atrophic gastritis leading to complete atrophy of fundus and resulting in achlorhydria. In PA, the lack of acid induces continuous gastrin cell activation and is responsible for the subsequent gastrin hypersynthesis and secretion. In ZES, hypergastrinemia causes hypertrophy of the oxyntic mucosa, which, in addition, displays hyperplasia of parietal and mucus cells. In both diseases, hypergastrinemia also induces the hyperproliferation of enterochromaffin-like endocrine cells in the fundic mucosa, which can offer all aspects from hyperplasia, then dysplasia, until true carcinoid tumor. The influence of antisecretory treatments and MEN 1 in the ZES as well as that of several other factors and antrectomy in PA on the behavior of the different gastric cells is evoked. Finally, the role that gastrin and its receptor play in the maintenance of the normal development of gastric mucosa and gastric acid secretion is emphasized by results observed in gene knockout models.