Use of scavenging oxygen-derived free radicals to protect the rat against aspirin- and ethanol-induced erosive gastritis.

Oxygen-derived free radicals are cytotoxic and produce tissue damage. The effect of the radical scavengers allopurinol and dimethyl sulfoxide (DMSO) on aspirin- and ethanol-induced acute gastric mucosal injury was studied in the rat. Orogastric instillation of aspirin at 200 mg/kg produced, after 4 h, gastric mucosal injury in 30% of rats without pyloric ligation [score, 3.1 +/- 0.8 mm2, mean +/- standard error of the mean (SEM); n = 10] and in 80% of rats with this ligation (score, 10.4 +/- 1.2 mm2, mean +/- SEM; n = 10). Gavage with 1 mL of 2 or 5% allopurinol or DMSO at 24 h before and again just before aspirin administration completely protected rats with or without pyloric ligation against injury. Orogastric instillation of ethanol (1 mL of a 40% solution) produced, after 1 h, gastric mucosal injury in all rats with or without pyloric ligation (24.1 +/- 1.7 and 14.1 +/- 1.3 mm2, respectively, mean +/- SEM; n = 10). Gavage with 1 mL of 5% allopurinol or DMSO at 24 h before and again just before ethanol administration completely protected rats with or without pyloric ligation against injury. Protection against the aspirin- and ethanol-induced injury was not associated with any significant effect on the H+ output. The results suggest that oxygen-derived free radicals are directly implicated in the mechanism of aspirin- and ethanol-induced acute gastric mucosal injury and that scavenging these free radicals protects against injury by maintaining the integrity of the gastric mucosa.