Research Article
Dose-Dependent Pattern of Cochlear Synaptic Degeneration in C57BL/6J Mice Induced by Repeated Noise Exposure
Table 2
Cochlear function and synaptic morphology changes related to repeated noise exposure at various intensities.
| Frequency | Intensity (dB SPL) | Function | Synaptic morphology | Threshold shifts at 1 day after NE | Threshold shifts at 14 days after NE | Decreased ABR wave I amplitude | Ribbon synaptopathy | MOC efferent synaptic degeneration |
| 8 kHz | Low | 88, 91, 94 | (-) | (-) | (-) | (-) | (-) | Moderate | 97 | (+) | (-) | (-) | (+) | (+) | 100 | (+) | (-) | (+) | (+) | (+) | High | 103 | (+) | (-) | (+) | (+) | (-) | 106 | (+) | (+) | (+) | (+) | (-) |
| 16 kHz | Low | 88, 91, 94 | (-) | (-) | (-) | (-) | (-) | Moderate | 97 | (+) | (-) | (-) | (-) | (-) | 100 | (+) | (-) | (+) | (+) | (-) | High | 103 | (+) | (+) | (+) | (+) | (-) | 106 | (+) | (+) | (+) | (+) | (-) |
| 22 kHz | Low | 88, 91, 94 | (-) | (-) | (-) | (-) | (-) | Moderate | 97 | (+) | (-) | (+) | (+) | (+) | 100 | (+) | (+) | (+) | (+) | (+) | High | 103 | (+) | (+) | (+) | (+) | (-) | 106 | (+) | (+) | (+) | (+) | (+) |
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(+) indicates significant change; (-) indicates nonsignificant change.
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