Figure 3. The PARP-1 inhibitors exhibit neuroprotection on light-damaged retinal ganglion cell (RGC)-5 cells. A: The upper panel shows representative western blots of PARP-1 and β-actin from cell lysates. B: The neuroprotection of light-damaged RGC-5 cells by PARP-1 inhibitors. RGC-5 cells were pretreated with PARP-1 inhibitors benzamide, nicotinamide, or NU1025 and the pan-caspase inhibitor Z-VAD-FMK and then exposed to 2,600 lx light for 3 days. Cell viability was determined with the MTT assay. Treatment with PARP-1 inhibitors significantly increased cell viability after exposure to light, while the pan-caspase inhibitor failed to protect RGC-5 cells from light injury. The results are expressed as a percentage of the control cells and are mean values±SEM (n=48, three separate cultures) (***p<0.001, one-way ANOVA and Bonferroni test). C: The active forms of cleaved caspase-3 and caspase-9 were not detectable in the light-treated cell lysates. Lt, light situation. Dark, dark control. Con, Etoposide-treated cell lysates as a positive control.