Abstract
Purpose::
To investigate the involvement of enzymatic antioxidant in NMDA-induced retinal excitotoxicity.
Methods::
Eight-week-old male Wister rats were used as subjects. Eyes were enucleated 1 and 7 days after intravitreal injection of NMDA (20 nmol) or PBS. The expressions of antioxidant enzymes, including superoxide dismutase 1(SOD1), SOD 2, catalase (CAT), and glutathione peroxidase (GPX), were examined by Western blot analysis. The effect of N-tert-butyl-(2-sulfophenyl)-nitrone (S-PBN), a free radical scavenger, on retinal neuronal cell survival was tested by transverse retinal sections with hematoxylin-eosin staining 7 days after simultaneous injection.
Results::
Western blot analysis showed that there were decreases of SOD1 and SOD2 proteins in the retina 1 day after NMDA injection. At this time, GPX remained unchanged, whereas CAT tended to be increased. Simultaneous injection of S-PBN and NMDA showed better preserved inner retinal segments (as evaluated with cell number in the retinal ganglion cell layer and thickness of inner plexiform layer) compared with NMDA injection alone.
Conclusions::
The expression of enzymatic antioxidant may vary dependent on time course of NMDA injection. A free radical scavenger such as S-PBN may have a beneficial effect on NMDA-induced retinal damage.
Keywords: oxidation/oxidative or free radical damage • excitatory amino acid receptors • enzymes/enzyme inhibitors