Abstract
Abstract: :
Purpose: To examine age–dependent differences in activities of antioxidant enzymes (catalase, glutathione peroxidase, superoxide dismutase) in rabbit corneas. Methods: Activities of superoxide dismutase, glutathione peroxidase and catalase were studied in corneas of normal eyes (albino rabbits) of various age (1 month – young eyes, 4 – 6 months – young adult eyes, 2.0 – 2.5 years – middle aged eyes, 3.1 – 5.1 years – aged eyes). Activities of glutathione peroxidase and superoxide dismutase were investigated biochemically in the scraped corneal epithelium. Catalase activity was examined histochemically in the corneal epithelium and endothelium. Results: Activities of corneal antioxidant enzymes differed according to the age of animals. Young corneas revealed lower activities of all enzymes investigated than young adult corneas, where enzyme activities reached the maximum. In middle aged corneas glutathione peroxidase and catalase remained approximately at the same levels as compared to young adult corneas, whereas superoxide dismutase activity was decreased. In aged corneas activities of all enzymes under investigation were dramatically decreased or even lost (superoxide dismutase in the epithelium, catalase in the endothelium). Conclusions: Glutathione peroxidase, superoxide dismutase and catalase are important enzymes cleaving reactive oxygen species thus protecting the cornea against the oxidative damage. Results of this study show that young adult corneas reveal the most pronounced activities of antioxidant enzymes, whereas in young and particularly aged corneas much lower enzyme activities can be found. Based on the findings it is suggested that young and aged corneas might be more susceptible to oxidative stress than young adult corneas. Support: The grant No.304/03/0419 from Grant Agency of CR.
Keywords: aging • cornea: basic science • enzymes/enzyme inhibitors