Effects of Omeprazole, a Proton Pump Inhibitor, on Pepsinogen-Producing Cells, with Special Reference to Neonatal Development

Abstract

Omeprazole, a proton pump inhibitor, exerts its effects by binding covalently to the H⁺/K⁺-ATPase that is located in the apical membrane of gastric parietal cells. However, its effects on pepsinogen-producing cells have not been investigated in detail and results of previous relevant studies on pepsinogen secretion are conflicting. Gastric mucosal cells proliferate and differentiate under an acidic environment in the gastric lumen. Thus, it is probable that omeprazole-induced reduced acidity in the gastric lumen has some influences on the proliferation and differentiation of the mucosal cells. As the first step to elucidate the effects of omeprazole on pepsinogen-producing cells, we analyzed the processes from the gene expression to the secretion of pepsinogen in vivo in adult rat glandular stomach. Next, we investigated the effects of omeprazole on the development of rat gastric mucosa biochemically and histologically, with special reference to pepsinogen expression as a marker of terminal differentiation.