Figure 2. Pre-treatment with SKF-83959 attenuated H₂O₂-induced death in RGC-5 cells. RGC-5 cells were pre-treated with either various concentrations of SKF-83959 or vehicle for 30 min prior to and during H₂O₂ treatment for an additional 5 h. A-F: Cell death was detected with PI staining. The dead cells were positively tracked with PI shown in red fluorescence. Left panel: fluorescence images (PI). Right panel: merged fluorescent images with binocular convert images. A, B: RGC-5 cells were treated with 500 μM H₂O₂; C, D, pretreated with 30 μM SKF-83959 before 500 μM H₂O₂; E, F, or vehicle. Scale bar = 50 μm. G: Cell viability was determined via the MTT assay. Data are expressed as percentage of relative cell viability (mean±SEM, from at least three independent experiments) in relation to control treatment. ***p<0.001, compared with 500 μM H₂O₂ treatment. H: Antagonist of the D1 receptor, SCH23390, abolished the SKF-83959-induced neuroprotection. Again, viability of RGC-5 cells was determined by MTT assay. Data were obtained from at least three independent experiments and expressed as the mean±SEM. ***p<0.001, compared to the SKF-83959 treated cells.