Superoxide dismutase, catalase, glutathione peroxidase and xanthine oxidase in diabetic rat lenses

The activities of the protective enzymes, superoxide dismutase, catalase, g lutathione peroxidase and of xanthine oxidase, an enzyme acting as a source of O-2(-), were measured in the lenses of alloxan-induced diabetic and con trol rats, Superoxide dismutase and glutathione peroxidase activities were found to be significantly decreased, while catalase and xanthine oxidase ac tivities were increased. This means that the ratio of the oxidant/antioxida nt enzymes increases in the diabetic rat lens, suggesting an increased oxid ative stress. This imbalance is possibly an important contributing factor i n the pathogenesis of diabetic cataract.