Glutathione attenuates the nitric oxide-induced retinal lipid and protein changes

Abstract

Purpose: Nitric oxide is a pro-oxidant associated with a number of retinal diseases. 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 by two-dimensional gel electrophoresis (2-DE). 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 samples.

Results: SNP significantly increased retinal-MDA levels (p=0.0002). Two-dimensional gel images displayed significant changes in the expression of 13 protein spots (p<0.05). GSH suppressed the SNP-induced MDA elevation (p<0.0001) and selected protein changes (p<0.05). As confirmed by Western blots, SNP down-regulated the expression of paraoxonase/arylesterase 2 precursor (PON2), b-actin and b-tubulin, however these effects were blocked by the co-incubation with GSH.

Conclusions: Nitric oxide induced lipid and protein changes in retinal tissues. The effects were prevented by GSH co-incubation. This study suggests that nitric oxide-induced retinal oxidative stress induces specific molecular changes. Further studies are indicated to explore potential pharmacological applications of GSH in nitric oxide-related retinal diseases.