脉冲噪声暴露后大鼠耳蜗外毛细胞死亡的启动方式

目的:观察强脉冲噪声暴露后大鼠耳蜗毛细胞死亡的启动方式。方法:将大鼠暴露于平均压力峰值级为154 dB SPL的脉冲噪声100发,分别于噪声暴露后10 m in,3 h,6 h解剖取耳蜗,应用细胞核DNA染料碘化丙锭(prop id ium lod ide,PI)标记耳蜗基底膜细胞,荧光显微镜下观察毛细胞核形态学变化。结果:强脉冲噪声暴露后10 m in可见到核固缩的外毛细胞,3 h出现少量核肿胀和核缺失外毛细胞,6 h可见到外毛细胞核大片段缺失。结论:毛细胞凋亡发生于脉冲噪声暴露后即刻,坏死出现于凋亡之后。细胞凋亡过程迅速,噪声暴露后6 h耳蜗基底膜外毛细胞核的缺失主要源于凋亡细胞。

Initial pattern of outer hair cell death in rat cochlea after exposure to impulse noise

Objective:To observe the initial pattern of outer hair cell(OHC)death in rat cochlea after exposure to impulse noise.Methods:Rats were exposed to 100 pars of impulse noise(3 seconds interval between each pair) at 154 dB SPL.Before and three times(10 min,3 h,and 6 h) after the noise exposure,the animals were sacrificed and the organs of Corti were processed for detection of OHC death modes.The apoptotic and necrotic OHCs were distinguished by propidium iodide(PI).The specimens were examined under a fluorescence microscope for assessment of OHC damage.Results:Morphological examination of OHC nuclei revealed some slightly nuclear condensation and fragmentation in the damaged cochlear region in the animals 10 min after the noise exposure.There were a few swollen nuclei and loss of OHC nuclei could be seen 3 h after the noise exposure.The cochlear lesion expanded containing many missing OHCs and seriously shrunken nuclei 6 h after the noise exposure.(Conclusions:The) results of the study indicate that apoptosis of OHCs takes place extremely rapid after the impulse noise exposure.The necrosis of OHCs is secondary to apoptosis.OHC apoptosis is a quick process.The early expansion of cochlear lesion is contributed primarily by apoptosis.