宽频带白噪声适度暴露对小鼠听力损害的实验研究

Effects of Moderate Level Noise Exposure on Hearing Function in C57BL/6J Mice

目的：通过100dB SPL宽频带白噪声对成年C57小鼠进行单次2小时的暴露，观察该种噪声对小鼠听功能损害的特点。方法选取5-6周龄ABR听阈正常的C57小鼠（每组5-7只），随机分为5个实验组分别为：噪声暴露后即刻（P0）、1天（P1）、3天（P3）、7天（P7）、14天（P14）。实验组小鼠于100dB SPL宽频带白噪声环境下暴露2h，本实验采用噪声暴露前的小鼠作为对照组。每只实验小鼠分别于噪声暴露前及暴露后各时间点进行ABR阈值检测以评估听力受损情况，实验采用统计噪声暴露前、后各时间点小鼠ABR差值（阈移）的方法分析实验结果。结果噪声暴露后即刻，小鼠各频率的ABR阈移均为最大值（P〈0.01）：Click（11.92±7.51dB）、4kHz（11.92±5.60dB）、8kHz（12.31±5.99dB）、16kHz （21.54±8.75dB）、32kHz（20.00±8.90dB），且在各个频率的阈移中，以16kHz及32kHz处的高频听力损失最严重，明显高于Click、4kHz及8kHz处的阈移（P〈0.05）。脱离噪声环境24小时后各频率的ABR阈移开始下降，2周以后，小鼠各频率ABR阈值均完全恢复至暴露前水平（P〉0.05）：Click（1.11±6.01dB）、4kHz（1.11±3.33dB）、8kHz（1.11±4.17dB）、16kHz （1.67±4.33）、32kHz（2.78±4.41）。结论100dB SPL宽频带白噪声单次有限暴露可以造成小鼠出现一定程度的听力损害。在频率分布上，高频区域的听力损害更为明显。同时，本研究表明，这种噪声下小鼠听力损害可以表现自我主动恢复的特征。

Objective To study characteristics of hearing loss in C57BL/6J mice after being exposed to a moderate level noise. Methods Male C57BL/6J mice with normal hearing at age of 5-6 weeks were chosen for this study. The mice were ran-domly selected to be tested immediately after exposure （P0）, or 1 day （P1）, 3 days （P3）, 7 days （P7） or 14 days （P14） after expo-sure. Post-exposure hearing was compared to before exposure. Mice were exposed to a white noise of 100 dB SPL for 2 hrs. ABR thresholds were used to estimate hearing status at each time point. Results Maximal ABR threshold elevations compared to before exposure were seen at P0 at every frequency （P〈0.01）, more so at high-frequencies （16 kHz and 32 kHz） than lower frequencies （4 kHz and 8 kHz） （ P〈0.05 ）. From P1 to P14, ABR thresholds were found to decrease progressively, and showed no significant differences from before exposure on P14 （P〉0.05）. Conclusions There is a frequency specific response to 100 dB SPL white noise exposure in C57BL/6J mice. High-frequency is more susceptible to the exposure. Also, the hearing loss in-duced by this moderate level noise exposure is reversible in C57BL/6J mice.