Effects of free radical scavengers on indomethacin-induced aggravation of gastric ulcer in rats.

Effects of treatment with free radical scavengers in the healing process of acetic acid-induced gastric ulcer on the ulcer aggravation induced by indomethacin were investigated. Gastric ulcers were produced on the anterior wall of the stomach of male Sprague-Dawley rats by submucosal injection of 20% acetic acid. To investigate the role of oxygen radicals, rats with gastric ulcer were treated with scavengers for six weeks and then treated with indomethacin (1 mg/kg/day). While superoxide dismutase (10,000 units/kg/day) did not affect the ulcer area after indomethacin treatment, allopurinol (50 mg/kg/day) slightly inhibited the increase in ulcer area. Dimethyl sulfoxide (1% solution, ad libitum) produced a significant decrease in size of the ulcer after indomethacin treatment. Increased lipid peroxides in the gastric mucosa after indomethacin treatment decreased significantly in the rats of the dimethyl sulfoxide and allopurinol groups. These results indicate that lipid peroxidation mediated by oxygen radicals plays an important role in the mechanism of ulcer aggravation induced by indomethacin.