| Purpose. To determine whether (a) oxidative cellular injury mediated by peroxynitrite, a reaction product of nitric oxide (NO ·) and superoxide (O2·-) and (b) expression of NO· synthesizing enzymes, nitric oxide synthases (NOS)-I, II, or III, play a role in neuronal degeneration in the lateral geniculate nucleus (LGN) in glaucoma. Methods. LGN sections of monkeys with experimental glaucoma with survival periods between 1 to 14 months and of normal control monkeys were studied. Immunohistochemistry was used to detect nitrotyrosine, an oxidative protein modification mediated by peroxynitrite, and NOS-I, II, and III in the LGN. Results. Nitrotyrosine immunoreactivity was detected in profiles in the LGN parenchyma and blood vessel endothelium in LGN sections of all glaucoma monkeys, compared to rare immunoreactivity in control LGN sections. Of the three NOS isoforms examined, only NOS-III was upregulated in the LGN of glaucoma monkeys with a 14-month survival period. Conclusion. The presence of nitrotyrosine in the LGN in experimental glaucoma suggests that peroxynitrite mediated cell injury occurs in the LGN in glaucoma and may contribute to LGN degenerative changes. |
