N-Methyl-D-Aspartate Receptors Involvement in the Gentamicin-Induced Hearing Loss and Pathological Changes of Ribbon Synapse in the Mouse Cochlear Inner Hair Cells

Figure 3

A low dose of gentamicin-induced moderate hearing loss with no obvious HC loss. The HCs were identified by immunostaining for myosin 7a (red) in the three turns of the cochlea. (a–c) After gentamicin treatment for 4 and 7 days, the morphology and arrangement of cochlear HCs were similar to the control group. (d-e) Quantitative data showed no HC loss in any of the three turns after gentamicin treatment. No significant difference was found in the number of IHCs or the three rows of OHCs among the control group and the gentamicin-treatment groups for 4 days or 7 days (). (f) A significant increase was observed in the ABR thresholds for clicks and for tone bursts at 4, 8, 16, and 24 kHz in the gentamicin-treated groups (, versus the control group). (g) A significant decline was observed in the ABR wave I amplitudes at 16 kHz in the gentamicin-treated groups (, versus the control group). GM 4 d, 7 d: gentamicin treatment for 4 days or 7 days; IHC: inner hair cell; OHC: outer hair cell. Scale bar = 10 μm. .