风洞噪声对小鼠脑干诱发电位的影响及其超微结构改变

Effects of wind tunnel noise on auditory auditory brainstem response and ultrastructural changes of cochlea in mouse

目的观察暴露于风洞噪声后小鼠脑干诱发电位(auditory brainstem response,ABR)及其超微结构改变。方法随机选择昆明小鼠15只暴露于风洞噪声环境中,于实验前和接噪3、7d及脱噪3、7d分别测试各组小鼠ABR阈值,并分别于接噪7d、脱噪7d处死小鼠各两只,取其耳蜗标本行扫描电镜、透射电镜检查。结果实验前小鼠ABR阈值(18.6±6.15)dB SPL,暴露于风洞噪声3、7d时其ABR阈值均比实验前增高,分别为(35.00±6.92)、(44.46±8.85)dB SPL,差异具有统计学意义(t=-9.69、t=-13.13,P<0.05);在脱噪3、7d后小鼠ABR阈值均有不同程度恢复,分别为(37.22±9.27)、(23.75±6.63)dB SPL,与实验前比较仍未恢复达正常水平(t=-8.699、t=-2.88,P<0.05)。扫描电镜显示,接噪7d时小鼠耳蜗内外毛细胞局限性片状缺失;脱噪7d时较前有所恢复,表现为耳蜗内外毛细胞局限性点状缺失。透射电镜观察小鼠接噪7d时耳蜗内外毛细胞胞核内空泡形成,细胞线粒体减少;脱噪7d后其毛细胞内空泡逐渐减少。结论风洞噪声能造成小鼠ABR听阈及耳蜗形态学改变:接噪7d后损伤最重,脱噪7d较前有所恢复。ABR听阈改变与扫描电镜、透射电镜结果相符。

Objective To observe the auditory brainstem response(ABR)changes and ultrastructural changes of cochlea in mouse exposed to the wind tunnel noise. Methods Fifteen mice were randomly selected and exposed to the wind tunnel noise environment.Auditory brainstem response(ABR)thresholds were measured before the experiment,in-noise for 3days,in-noise for 7days,3days off-noise recovery,and 7days off-noise recovery,respectively,and the mice cochlea was observed by scanning electron microscope(SEM)and transmission electron microscope(TEM).Results ABR threshold of mice exposed to the wind tunnel noise in 3and 7days increased as compared with that before the experiment,with significant difference(P<0.05);the ABR threshold had a certain extent recovery after they were off-noise in 3and 7days.Scanning electron microscopy showed that cochlear hair cells appeared a local sheet missing after 7days of exposure to noise,and point-like missing of the cochlea after 7days off-noise.TEM showed that the hair cells after noise exposure presented vacuolization in nuclei and decreased mitochondria.Conclusion Wind tunnel noise could damage the hearing thresholds and induce cochlear morphological changes of the mice.The mice have received the heaviest damage after they are exposed to the wind tunnel noisy environment for 7days,which show an significant recovery after removed off noise for 7day.The changes in ABR hearing threshold are consistent with the findings of SEM and TEM.