Nitric oxide participates in cataract development in selenite-treated rats

Purpose. The role of nitric oxide in the development of selenite-induced cataracts in rats was examined using nitric oxide synthase (NOS) inhibitors. Methods. Subcutaneous injection of sodium selenite was used to induce cataracts in rats, with or without pretreatment with NOS inhibitors. The anterior eye segment analysis system (EAS-1000, Nidek) was used to measure lens opacity. The glutathione content of the lenses was determined by an HPLC method and the Ca2+ content by atomic absorption spectrometry. Nitrite, a stable metabolite of nitric oxide, was determined fluorometrically. NADPH-diaphorase activity staining and Western blot analysis were used to determine NOS levels. Results. Administration of the NOS inhibitor, N-G-nitro-L-arginine methyl ester (r-NAME), inhibited lens opacification in selenite-treated rats. NG-nitro-D-arginine methyl ester, an inactive enantiomer of L-NAME, had no effect. Aminoguanidine, another NOS inhibitor, also inhibited the development of cataracts in a dose-dependent manner. On the other hand L-arginine, a substrate of NOS, accelerated the development of cataracts. Although the opacification of the lenses was apparent approximately 3 days after selenite injection, the nitrite level was increased within one day. In addition, NOS was induced in the eye within one day of selenite injection. Conclusions. The present study demonstrated that NOS inhibitors prevented the development of cataracts in selenite-treated rats. The results also suggest that nitric oxide had an important role in the development of selenite-induced cataracts.