Fig. 4. Outer hair cells are reduced in CSA^−/− and CSB^m/m mice, and short-term NR supplementation rescues outer hair cell loss in CSB^m/m mice.

a Summary data for the average number of outer (left) and inner (right) hair cells per 100 μm in the basal region of the cochlea in WT or CSB^m/m mice with and without NR treatment (12 mM in drinking water for 10 days) at 6.5 weeks of age. The decreased number of outer hair cells observed in CSB^m/m mice is prevented by NR treatment. In contrast, no changes in the number of inner hair cells were observed between conditions. N = 4; mean ± S.E.; two-way ANOVA with Tukey’s post-hoc test was used to determine significant difference. b Representative images of outer and inner hair cells in the cochlear base region of CSB^m/m and WT mice following NR treatment as described in a. Myo7a staining is used to identify hair cells. c Outer hair cells were reduced in base region in CSA^−/− mice (CSA^−/− (N = 4); CSA^−/− + NR (N = 3); WT (N = 4); WT + NR (N = 5)). Mean ± S.E.; two-way ANOVA with Tukey’s post-hoc test was used to determine significant difference. d Representative images of base outer and inner hair cells of CSA^−/− and WT mice following NR treatment as described in c. Myo7a staining is used to identify hair cells.