The Prestin-CreER^T2 knockin homozygous mice exhibit fewer threshold shifts in the acute phase of cochlear pathogenesis (2 h after the noise exposure).

<p><b>A</b> Elevation of ABR thresholds at 2 h after the noise exposure. <b>B</b> Comparison of the percentages of the average detectable ABRs among the three groups (the Prestin-CreER^T2 homozygous, heterozygous and wild-type groups). Detectable ABRs were defined as ABRs that could be visually identified within the intensity range of the stimuli. The percentage of detection is 100% for the homozygous mice. By contrast, the values are 40.6±45.9% for the wild-type mice and 60.8±42.8% for the heterozygous mice. Both are significantly lower than that of homozygous mice (one-way ANOVA; <i>F_2,65</i> = 23.039, <i>P</i><0.001; *** indicates <i>P</i><0.001 tested by Tukey test). In addition, the heterozygous mice had a greater detectable rate than that observed for the wild-type mice (* indicates <i>P</i> = 0.045 tested by Tukey test). <b>C</b> Comparison of the ABR threshold shifts among the Prestin-CreER^T2 mice (+/+ and +/-) and wild-type mice. The levels of the threshold shift of the homozygous mice are significantly smaller than those of the heterozygous and wild-type mice (two-way ANOVA, two-way ANOVA, <i>F_{2, 244}</i> = 56.11, <i>P</i><0.001; *** indicates <i>P</i><0.001 tested by Tukey test). These results indicate that the Prestin-CreER^T2 knockin homozygous mice have a reduced level of hearing loss at the early phase of acoustic trauma.