Role of oxygen-derived free radicals in the mechanism of cysteamine-induced duodenal ulcer in rats.

In this study, the possible role of oxygen-derived free radicals in cysteamine-induced duodenal ulcers in rats was investigated. Separate groups of rats were treated with 350 mg/kg cysteamine subcutaneously. Superoxide dismutase (SOD) activity and thiobarbituric acid (TBA) reactants in the duodenal mucosa were analyzed one, three, six, 12 and 24 hours after treatment, respectively. Cu,Zn-SOD activity significantly decreased from 41.79 +/- 3.53 NU/mg protein to 29.56 +/- 3.62, 27.23 +/- 3.02 and 24.64 +/- 3.07 NU/mg protein at three, six and 12 hours, respectively. TBA reactants, indicators of tissue injury by oxygen-derived free radicals, significantly increased from 0.18 +/- 0.10 nmol/mg protein to 1.31 +/- 0.12 and 1.57 +/- 0.09 nmol/mg protein at six and 12 hours after cysteamine treatment, respectively. We conclude that an increase of oxygen-derived free radicals and a decrease of Cu,Zn-SOD activity in the duodenal mucosa may be involved in the pathogenesis of cysteamine-induced duodenal ulcers in rats.