Glutathione attenuates nitric oxide-induced retinal lipid and protein changes

Background: Elevated levels of nitric oxide (NO•), a pro-oxidant that has been associated with numerous retinal diseases, have been implicated in experimental glaucoma models. This study investigated the oxidative effects of sodium nitroprusside (SNP), a nitric oxide donor, on the retinal lipids and proteins and evaluated the potential protective effects of glutathione (GSH). Methods: Porcine retinal homogenates were incubated with 0, 1, 2, 3, 4 and 5 μm SNP. Malondialdehyde (MDA) levels were assayed spectrophotometrically to quantify lipid peroxidation. Differential protein expressions of 3 μm SNP-treated retinal homogenates were compared with controls after the conduction of two-dimensional gel electrophoresis. Mass spectrometric data was used to identify proteins in NCBInr database. Furthermore, GSH was co-incubated with 3 μm SNP-treated retinal homogenates. MDA levels and protein expressions were compared with SNP-treated controls. Results: SNP significantly increased retinal-MDA levels (p = 0.0002). 2-D gel electrophoresis images displayed a significant change in 13 protein spot expressions (p < 0.05). GSH suppressed SNP-induced MDA elevation (p < 0.0001) and selected protein changes (p < 0.05). SNP down-regulated paraoxonase/arylesterase 2 precursor (PON2), β-actin and β-tubulin; however, these effects were prevented by a co-incubation with GSH, as confirmed by Western blots. Conclusions: Nitric oxide induced lipid and protein changes in retinal tissues. The effects were partially reversed by co-incubation with GSH. Data from this study suggests that nitric oxide-induced retinal oxidative stress induces specific molecular changes. This may enable us to better understand the pathogenesis of glaucoma. Further studies are indicated to explore potential pharmacological applications of GSH in nitric oxide-related retinal diseases.School of Optometr