The mechanisms underlying the neuroprotective effects of the hybrid antioxidant-nitric oxide donating compound SA-2 in retinal ganglion cell (RGC) degeneration models were evaluated. The in vitro trophic factor (TF) deprivation model in primary rat RGCs and ex vivo human retinal explants were used to mimic glaucomatous neurodegeneration. Cell survival was assessed after treatment with vehicle or SA-2. In separate experiments, tert-Butyl hydroperoxide (TBHP) and endothelin-3 (ET-3) were used in ex vivo rat retinal explants and primary rat RGCs, respectively, to induce oxidative damage. Mitochondrial and intracellular reactive oxygen species (ROS) were assessed following treatments. In the TF deprivation model, SA-2 treatment produced a significant decrease in apoptotic and dead cell counts in primary RGCs and a significant increase in RGC survival in ex vivo human retinal explants. In the oxidative stress-induced models, a significant decrease in the production of ROS was observed in the SA-2-treated group compared to the vehicle-treated group. Compound SA-2 was neuroprotective against various glaucomatous insults in the rat and human RGCs by reducing apoptosis and decreasing ROS levels. Amelioration of mitochondrial and cellular oxidative stress by SA-2 may be a potential therapeutic strategy for preventing neurodegeneration in glaucomatous RGCs.
Keywords: apoptosis; endothelin; glaucoma; mitochondria; neuroprotection; neurotrophic factor; oxidative stress; reactive oxygen species; retinal ganglion cells.