目的 观察120dB宽频带白噪声对C57BL/6J小鼠听阈阈值、耳蜗基底膜毛细胞形态与带状突触数量的影响.方法 :20只听力正常的5-6周龄C57BL/6J小鼠随机分为四组,3组实验组,分别为给予白噪声后立即测量组(0d)、噪声暴露后7天测量组(7d)、噪声暴露后14天组(14d);1组对照组.每组5只小鼠(n=10),实验组小鼠120dB白噪声暴露2h,0d组立即测量小鼠听阈,7天和14天应用相同方法 测量小鼠听阈值,并计算出每只小鼠噪声暴露前后的阈移值.各组测量阈值后立即处死取耳蜗用4%多聚甲醛固定后进行免疫荧光染色和扫描电镜检查,观察小鼠带状突触与内外毛细胞形态变化并计数.结果 噪声暴露2h后即刻组其各个频率5只小鼠(n=10)阈值均未引出,暴露后七天小鼠听阈部分恢复(P<0.01).暴露后第14天,14天组各频率的听阈继续恢复,但与暴露前的差异较第7天比有所减小,但仍有统计学差异(所有P<0.01).并且观察到带状突触明显减少,扫描电镜观察外毛细胞纤毛有倒伏粘连.结论 120dB白噪声噪声暴露2小时能够造成小鼠听力永久性阈移,外毛细胞明显损伤,带状突触数量明显减少.%Objective To investigate changes of hearing threshold, morphology and the ribbon synapses in the co-chlear basilar membrane after 2 hours exposure to white noise at 120 dB SPL in C57BL/6J mice. Methods Twenty C57BL/6J mice with normal auditory thresholds were randomly divided into four groups (n=5, 10 ears, in each group). Animals in three groups (experiment groups) were examined at 0 day, 7 days and 14 days after noise exposure. One group was used as control. Immunofluorescent staining and scanning electron microscopy (SEM) examination focusing on morphology of OHCs and ribbon synapses were conducted after auditory brainstem response (ABR) testing. Result Auditory thresholds could not be detected at 0 day after noise exposure. Compared with the control, ABR thresholds re-mained elevated at 7 day after noise exposure (P<0.01). ABR thresholds at 14 days after noise exposure were better than at 7 days after, although still worse than the control (P<0.01). There was an obvious decrease in the number of ribbon synapsis. Adhesion and disarray of OHC stereocilia were seen on SEM. Conclusions Exposure to white noise at 120 dB SPL for 2 hours can lead to permanent threshold shift (PTS) in mice, causing severe damage to OHC and decrease of rib-bon synapses.
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