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. 2022 Feb 8;7(3):e148586. doi: 10.1172/jci.insight.148586

Figure 2. Early onset of hearing impairment in Ndp-KO mice.

Figure 2

ABR (A and B) and DPOAE (C and D) thresholds and endocochlear potentials (EPs) (E and F) for individual animals were plotted as mean ± SD from WT mice (blue) and Ndp-KO mice (red) aged 1 month and 2 months. Ck, click. (A) No difference in ABR thresholds between genotypes at 1 month (Mann-Whitney rank sum test; U = 1050, T = 2226, P = 0.4540). (B) Ndp-KO mice show hearing loss in low frequencies at 2 months (U = 2754.4, T = 5382.5, P = 0.0026). n = 11 WT, n = 12 Ndp-KO at 1 month; n = 9 WT, n = 13 Ndp-KO at 2 months. (C and D) DPOAEs were comparable between genotypes at 1 month (U = 1252.5, T = 2527.5, P = 0.1326). At 2 months, Ndp-KO thresholds increased over all frequencies compared with controls (U = 689.5, T = 1724.5, P < 0.00000001). n = 10 WT, n = 12 Ndp-KO at 1 month; n = 9 WT, n = 13 Ndp-KO at 2 months. (E) At 1 month, EP was significantly lower in Ndp-KO than in WT, but within normal range (>100 mV); n = 11 WT, n = 12 Ndp-KO. (F) At 2 months, Ndp-KO EP decreased further; n = 7 WT, n = 12 Ndp-KO (2-way ANOVA; significant effect of age, F = 4.3400, P = 0.0440; significant effect of genotype, F = 29.9970, P = 0.0000297). There was a significant reduction at 1 month (E) (Holm-Šidák method for multiple comparisons; t = 3.5946, P = 0.00092067) and at 2 months (F) (Holm-Šidák method for multiple comparisons; t = 4.1323, P = 0.00019031). n = 11 WT, n = 12 Ndp-KO at 1 month; n = 7 WT, n = 12 Ndp-KO at 2 months.