Abstract
Purpose: :
Oxidative stress is implicated in retinal ganglion cell (RGC) death in glaucoma. All the cells have elaborate defense mechanisms against oxidative stress. In this study, we investigated whether sublethal exposure of RGCs to oxidative stress can utilize these inherent mechanisms to protect against subsequent lethal challenge.
Methods: :
A murine RGC cell line, RGC-5, was used. RGC-5 cells were differentiated into neuronal morphology by staurosporine treatment. Differentiated RGC cells were exposed to increasing doses of sublethal H2O2 for 90 min (25 µM to 200 µM). The cells were then allowed to recover overnight, and subsequently were challenged with a lethal dose of H2O2 (800 µM). Cell numbers were assessed using a WST-1 kit. Specificity of the response was assessed by measuring reactive oxygen species by dihydrorhodamine. Possible mechanisms were investigated by inhibiting the glutathione (GSH) neosynthesis by buthionine sulfoximine (BSO), or blocking the NF-kB activity by (E)-3-(4-Methylphenylsulfonyl)-2-propenenenitrite (Bay 11).
Results: :
Staurosporine treatment induced neuronal morphology in RGC-5 cells. Preconditioning with sublethal dose of H2O2 protected the cells from cytotoxic effect of lethal dose. Inhibition of GSH synthesis by BSO increased the sensitivity of the RGC-5 cells to oxidative insult, but did not eliminate the protective effect of preconditioning. However, blocking NFkB abolished the effect of preconditioning.
Conclusions: :
Our results demonstrate that oxidative preconditioning can protect the RGCs from Cytotoxic effects of lethal doses. This protective effect is probably mediated by NF-kB.
Keywords: oxidation/oxidative or free radical damage • ganglion cells • retinal degenerations: cell biology