title: Glutathione attenuates nitric oxide-induced retinal lipid and protein changes.
abstract: 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.
authors.affiliation: Laboratory of Experimental Optometry, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Siu
authors.forename: Sze Wan
authors.initials: SW
authors.lastname: Shan
authors.forename: King Kit
authors.initials: KK
authors.lastname: Li
authors.forename: Hiu Yan
authors.initials: HY
authors.lastname: Lam
authors.forename: Man Yee
authors.initials: MY
authors.lastname: Fung
authors.forename: Ka Ki
authors.initials: KK
authors.lastname: Li
authors.forename: Chi Ho
authors.initials: CH
authors.lastname: To
authors.forename: Chi Wai
authors.initials: CW
authors.lastname: Do
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005136:Eye Proteins / Q000378:metabolism*; D005978:Glutathione / Q000494:pharmacology*; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology*; D012160:Retina / Q000187:drug effects* / Q000378:metabolism; D013552:Swine
chemical_list: D005136:Eye Proteins; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D009569:Nitric Oxide; D008315:Malondialdehyde; D005978:Glutathione
keywords: glutathione; lipid; nitric oxide; protein; retina