Superoxide dismutase in developing mouse retina

Superoxide dismutase (SOD) activity and the production site of H₂O₂ were studied in the developing mouse retina. The H₂O₂ production site moved from the inner to the outer region within the outer nuclear layer between the ages of 4 days through 12 days. This shift occurred in parallel with the development of the inner segments of the photoreceptor layer. SOD activity increased significantly at the age of 2-3 weeks. Both manganese-SOD (Mn-SOD) and copper-zinc SOD (Cu,Zn-SOD) activities (combined mean) in the retina of mice older than 2 weeks of age were 1.9 times greater in comparison with those of mice at the age of 2 weeks and younger. The mRNA of Cu,Zn-SOD did not change during these periods, suggesting that the translational efficiency of the mRNA and/or the stability of the SOD enzyme might increase, or the active form of the enzyme might increase during the development of the retina. The results of this study indicate that the localization and production of active oxygen change during the development of the mouse retina, and that SOD activity does exist in the retina from birth, increasing as its role in the protective system against active oxygen increases in the maturing mouse retina.