Reactive oxygen species in the pathogenesis of stress-induced gastric ulceration in rats and protective effect of omeprazole

To examine the role of reactive oxygen species (ROS) in stress-induced gastric ulceration and possible protective effect of proton pump inhibitor omeprazole male adult rats were immobilized for 9 hours. Phagocyte-derived ROS were measured using the chemiluminescence method in whole blood obtained at start and after 3, 6, and 9 hours of immobilization. As indirect sign of gastric mucosal damage faeces were examined after 3 and 6 hours for blood spots presence and after 9 hours the animals were killed and stomachs were examined. Stress resulted in a gigantic increase of ROS in immobilized animals both without and with omeprazole. Blood spots were not found after 3 hours of immobilization. After 6 hours, massive presence of blood spots was found in immobilized animals in contrast to minimal presence (P<0.001) in rats treated with omeprazole. The same difference was observed for macroscopically evaluated gastric mucosa after decapitation. We conclude that immobilization causes a large increase of ROS in rats and this increase is not influenced by omeprazole. In contrast, omeprazole decreased bleeding from gastric mucosa and dramatically decreased both number and severity of gastric mucosal lesions.