Fig. 3

Measurement of hearing function using ABR and DPOAE before and after Y-27632 treatment. a–c Changes in ABR threshold at various timepoints are shown in Fig. 2a. The ABR thresholds at 28 days after Y-27632 treatment (green filled diamonds) are not significantly different from those at pre-LISW exposure (black filled circle) in any treatment groups, although the temporal threshold shifts at 1 day after LISW exposure can be observed. d–f ABR wave I amplitudes at the same timepoints as in a-c. Similar to the ABR threshold changes, a decrease in temporal amplitude can be observed at 1 day after LISW exposure in any groups. However, in the 1 mM Y-27632-treated group, the amplitude at 28 days after treatment (green filled diamonds) from 8 to 16 kHz is still significantly (black asterisks) lower than that at pre-LISW exposure (black filled circle). In 10 mM Y-27632 treatment group, the amplitude at 28 days after treatment (green filled diamonds) at any frequencies is not significantly different from that at pre-LISW exposure (black filled circle). However, the amplitudes at 28 days after treatment (green filled diamonds) at 8 kHz and 16 kHz are significantly larger than those at post-LISW exposure (red filled squares). g–i Changes in DPOAE threshold at various timepoints are shown in Fig. 2a. No significant elevations can be observed in the DPOAE thresholds in any treatment group. j An example of 16 kHz ABR waves recorded at 28 days after Sham surgery and 10 mM Y-27632 treatment. Bilateral arrows show the wave I amplitude at 80 dB SPL. Arrowheads show the peaks with the largest peak-to-peak amplitude. In the Y-27632-treated ear, the peak could first be detected at 25 dB, while on the control side, the peak could first be detected at almost the same sound pressure level. k The representative figure of the input–output curve recorded at 28 days after Sham surgery (filled circle), 1 mM Y-27632 treatment (filled square), and 10 mM Y-27632 treatment (filled triangle). Black asterisk indicates significant changes in the value at 28 days after treatment than at pre-LISW exposure (p < 0.05, two-way ANOVA, followed by Bonferroni correction for multiple comparisons). Red asterisk indicates significant changes in the value at 28 days after treatment than at post-LISW exposure (p < 0.05, two-way ANOVA, followed by Bonferroni correction for multiple comparisons). Values are represented as mean ± SEM