Neuroprotective effects of idebenone on hydrogen peroxide-induced oxidative damage in retinal ganglion cells-5

Abstract

Purpose: To investigate the neuroprotective effect of idebenone against hydrogen peroxide (H₂O₂)-induced oxidative damage in retinal ganglion cells-5 (RGC-5 cells).

Methods: RGC-5 cells were pre-treated with various idebenone concentrations (5, 10, and 20 µM) for 12 h and were then subjected to 300 µM H₂O₂ for a further 12 h. Apoptosis in RGC-5 was measured by flow cytometry. The changes of mitochondrial membrane potential (MMP) were detected by JC-1 staining. Autophagy in RGC-5 cells was observed by transmission electron microscopy. Western blots were used to measure the expression of autophagy-related protein light chain 3 (LC3), Beclin-1, and the release of Cytochrome c (Cyt-c).

Results: Flow cytometry showed that the apoptosis rates in the normal control group, H₂O₂ group, and idebenone groups were 6.48 ± 0.55%, 27.3 ± 0.51%, 22.8 ± 0.52%, 15.45 ± 0.81%, and 12.59 ± 0.58%, respectively (F = 559.7, P < 0.0001). After incubation with H₂O₂, the number of autophagosomes increased significantly, whereas it was decreased in the idebenone groups. After incubation of RGC-5 cells with H₂O₂, MMP levels were significantly decreased, while idebenone could prevent the decrease in MMP levels. Compared with that in the normal control group, LC3 II/I, the expression levels of Beclin-1 and Cyt-c were increased significantly in the H₂O₂ group (P < 0.05). Compared with that in the H₂O₂ group, LC3 II/I, the expression of Beclin-1 and Cyt-c was significantly decreased in idebenone groups (P < 0.05).

Conclusions: Idebenone protects RGC-5 cells against H₂O₂-induced oxidative damage by reducing mitochondrial damage and autophagic activity.

Keywords: Apoptosis; Autophagy; Glaucomatous optic neuropathy; Idebenone; Oxidative stress.