Gastrin is considered one of the most important hormones regulating physiological processes. Trophic and proliferative effects of high gastrin levels on gastric mucosa are well known. Butinformation about gastrin effects on the colon is rather fragmentary and contradictory. In this study, ultrastructural changes in the proximal part of the colon induced in rats by chronic hypergastrinemia were analyzed by transmission electron microscopy. Experimental omeprazole-induced hypergastrinemia was reproduced using daily injections of proton pump inhibitor omeprazole in rats, resulted in hypersecrestion of gastrin by G-cells of stomach. Growth of gastrin level in the blood plasmawas checked using radioimmunoassay method. Prolonged hypergastrinemia has been shown to be associated with increased cell proliferation and appearance of cellular atypia in the large intestine mucosa. The number of undifferentiated cellsincreased prominently. Intercellular contacts between such cells are altered, the space between them is unevenly expanded.Their organelles were observed significantly reduced, mitochondria contained destroyed crystas and signs of edema.Endocrinocytes did not contain their typical secretory granules. Cell nuclei were small, electron-dense, with inv&agination.In addition, numerous microorganisms were revealed in the intestinal lumen, as well as their invasion into the mucosa. Those ultrastructural changes were indicate increased hyperplastic processes and impaired cell differentiation in the epi&theliocytes of large intestine.Therefore, long-term experimental hypergastrinaemia cause dysplastic changes in the large intestine mucosaof rats.
