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, NG-nitro-L-arginine methyl ester (L-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.