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 inhi bitor omeprazole male adult rats were immobilized for 9 hours. Phagocy te-derived ROS were measured using the chemiluminescence method in who le blood obtained at start and after 3, 6, and 9 hours of immobilizati on. As indirect sign of gastric mucosal damage faeces were examined af ter 3 and 6 hours for blood spots presence and after 9 hours the anima ls were killed and stomachs were examined. Stress resulted in a gigant ic increase of ROS in immobilized animals both without and with omepra zole. Blood spots were not found after 3 hours of immobilization. Afte r 6 hours, massive presence of blood spots was found in immobilized an imals in contrast to minimal presence (P<0.001) in rats treated with o meprazole. The same difference was observed for macroscopically evalua ted gastric mucosa after decapitation. We conclude that immobilization causes a large increase of ROS in rats and this increase is not influ enced by omeprazole. In contrast, omeprazole decreased bleeding from g astric mucosa and dramatically decreased both number and severity of g astric mucosal lesions.