Figure 3.

Noise exposure increased immunolabeling for MCU in OHCs and the stria vascularis of the basal turn. (A) Paraffin sections of the adult CBA/J mouse inner ear revealed an increase in immunolabeling for MCU in DAB-stained OHCs (arrows and enlarged image inserts) in the organ of Corti (OC) and the stria vascularis (arrow) in the lateral wall, and no obvious change in spiral ganglion neurons (SGNs) examined 1 h after completion of the 101-dB noise exposure. These images were taken with 40×-magnification lens and are representative of five individual mice per group; scale bar = 10 μm. (B) Representative images for MCU in OHCs of surface preparations stained with phalloidin when processed 1 h after completion of the noise exposure. An enlarged image of three OHCs better illustrates the immunolabeling for MCU. Images were taken from the area of the basal turn corresponding to 22–32 kHz; OHC1, 2, 3 indicate the three rows of OHCs, scale bar = 10 μm. (C) Quantification of immunolabeling for MCU in OHCs in the 22–32 kHz region showed a significant increase when processed 1 h after and 24 h after completion of the exposure. Data are presented as individual points and means ± SD; *p < 0.05, **p < 0.001. Control: n = 8, 101-dB 1 h post: n = 8, 101-dB 24 h post: n = 6 with one cochlea from each mouse in the group. (D) Immunoblots using total cochlear homogenates of CBA/J mice revealed no difference in MCU band densities between control (Ctrl) and noise-exposed mice processed 1 h after completion of the noise exposure (101-dB 1 h post). GAPDH was used as a loading control; n = 8 mice per group.