Figure 5

Idebenone supplementation delayed photoreceptor cell death in rd1 retinas. (A) Quantification of ERG indicated that b-wave amplitudes of ERG showed no significant visual rescue in mice treated with idebenone, although there was a trend toward an increased response (black square box). WT mice exhibited more distinct waveforms than rd1 mice, irrespective of treatment. However, the amplitude of F-VEP showed significant visual rescue in mice treated with idebenone at P14, which was not significant at P21. (N = 4–10 eyes from different mice). (B) Histological examination of untreated or idebenone-treated rd1 retinas revealed that idebenone therapy promoted neuronal cell survival in the ONL at P14, though the effect was not significant at P21. Morphometric analysis of ONL thickness extending from the ONH also indicated that idebenone treatment notably preserved photoreceptor cells at P14. (N = 4–10 eyes from different mice, with multiple counts per eye). Image scale bar: 50 μm. (C) Retinal double staining using antibodies against PKCα (red) and CtBP2 (green) showed an increase in CtBP2-positive puncta following enhanced photoreceptor cell survival in rd1 mice treated with idebenone for 14 days, while the numbers remained unaltered and scarce in the treated groups at P21. In WT mice, the characteristic horseshoe-shaped CtBP2-positive puncta were observed, particularly at P21. (D) Rod bipolar cell (labeled with PKCα, red) and horizontal cell (marked by Calbindin, green) double-labeling revealed a substantial decrease in the terminal dendrites of horizontal cells in rd1 mice as opposed to their WT counterparts, while the untreated and idebenone-treated mice at the ages of P14 and P21 showed no differences. INL, inner nuclear layer; ONH, optic nerve head. Image scale bar: 50 μm. (E) Quantification of immunofluorescence staining indicated only CtBP2-positive area were increased following the photoreceptor cell survival in the rd1 mice after idebenone treatment for 14 days. (N = 3–6 eyes from different mice, n = 5 images from each eye). **P < 0.01, *P < 0.05 compared with untreated rd1 and idebenone-treated rd1 mice by one-way ANOVA with LSD’s multiple comparisons.