AN ELEVATED LEVEL OF COPPER-ZINC SUPEROXIDE-DISMUTASE FAILS TO PREVENT OXYGEN-INDUCED RETINOPATHY IN MICE

Background-To determine whether a higher level of copper zinc superoxi de dismutase (CuZnSOD) can reduce the severity of oxygen induced retin opathy (OIR) in a mouse model. Methods-CuZnSOD transgenic mice with a threefold increase in CuZnSOD activity and control non-transgenic mice were exposed to 90% oxygen for 12 hours a day during the first 5 days of life. After oxygen treatment, all mice were reared in room air for 10 days. Another group of transgenic and non-transgenic mice were kep t in room air for 15 days and served as control groups for the oxygen effect. At day 15, all mice were killed and perfused with India ink. T he retinas were flat mounted on slides and examined with a light micro scope. Results-There was a statistically significant increase in the i ncidence of OIR in mice exposed to high levels of oxygen, whether or n ot they were transgenic. However, there was no statistically significa nt difference in the severity of OIR between oxygen treated transgenic and non-transgenic mice. Conclusion-A threefold higher CuZnSOD activi ty does not protect considered a major factor causing OIR, and increas ed CuZnSOD activity has reduced oxygen radical induced damage in sever al neuronal and non-neuronal systems. The possibility of a damaging ro le for other radicals not affected by CuZnSOD cannot be excluded.