Fig. 1.

TUDCA decreases ABR thresholds in erl mice. (a) ABR thresholds in B6 and erl mice with or without TUDCA treatment at 4 weeks of age at stimuli of 8 kHz, 16 kHz, and 32 kHz tone bursts. The erl mutant mice exhibited higher ABR thresholds than B6 mice, and could be alleviated by TUDCA. The TUDCA-treated B6 mice exhibited similar hearing levels with untreated B6 mice. Data are presented as the mean ± s.e.m (n = 7 mice per group). ^**P < 0.01 from untreated B6 mice, ^# P < 0.05 from TUDCA-treated erl mice, student t-test. (b–e) ABR thresholds were obtained at 4, 6, 8, and 12 weeks (W) of mouse age for various stimuli: clicks (b) and tone bursts of 8 kHz (c), 16 kHz (d), and 32 kHz (e). ABR thresholds in the TUDCA group were significantly lower than those in the PBS group or the untreated group. No significant difference was found between the untreated and PBS groups. Data are presented as the mean ± s.e.m (n = 7 mice at 4 and 6 weeks per group; n = 5 mice at 8 and 12 weeks per group). ^**P < 0.01, ^*P < 0.05, one-way ANOVA test. (f) TUDCA exhibited similar or even better hearing improvement compared to Z-VAD-FMK at 12 weeks. ABR threshold shifts were calculated by untreated ABR thresholds minus the thresholds in each of TUDCA and Z-VAD-FMK treated studies. Data are presented as the mean ± s.e.m. (n = 5 mice in TUDCA group; n = 6 mice in Z-VAD-FMK group). *P < 0.05, student t-test.