单次放射线照射早期Balb/c小鼠畸变产物耳声发射变化和耳蜗外毛细胞Prestin蛋白表达的实验观察

摘要

Objective To study the effect of radiation exposure on the distortion product otoacoustic emission(DPOAE) and Prestin expression in the cochlear outer hair cells of Balb/c mice in the early period after single-dose radiation exposure and to examine the possible mechanism of radiation causing sensorineural hearing loss(SNHL). Methods The Balb/c mouse models with outer hair cells exposed to radiation were established. The DPOAE amplitudes of the mice were detected and compared before, 3 days and 7 days after exposure to a single dose of 16Gy radiation. The Western Blot and reverse transcription-polymerase chain reaction(RT-PCR) assays were used to analyze the changes of expression of Prestin and its mRNA in the cochleae of mice. Results The Balb/c mouse models with SNHL after radiation exposure were successfully established. The DPOAE amplitudes of the mice on the 3rd and 7th day after radiation exposure were lower than those before radiation exposure at 3,4,6,8,10 and 12 kHz and the amplitudes on the 7th day were lower than those on the 3rd day at most frequencies. The expressions of Prestin and its mRNA after radiation exposure were parallel down-regulated as compared with those before exposure and the expressions of Prestin and its mRNA on the 7th day after radiation exposure were lower than those on the 3rd day. Conclusion The auditory function of the mice was affected in the early period after radiation exposure. The mechanism of SNHL after radiation exposure may be correlated with Prestin expression abnormalities in the outer hair cells of cochleae in the early period after radiation exposure.%　　目的探讨放射线照射早期对Balb/c小鼠畸变产物耳声发射(DPOAE)和耳蜗外毛细胞Prestin蛋白的影响及放射线照射导致感音神经性耳聋的可能机制。方法建立放疗早期感音神经性耳聋(sensorineural hearing loss,SNHL)Balb/c小鼠模型。检测一次性给予单侧耳总放射剂量为16 Gy的放射线之前、照射后第3天、照射后第7天小鼠畸变产物耳声发射幅值,比较放射线照射前后小鼠听觉生理功能的变化情况。提取小鼠耳蜗组织蛋白及mRNA,通过Western blot及逆转录聚合酶链反应(reverse transcription-polymerase chain reaction,RT-PCR)方法检测各组小鼠耳蜗Prestin蛋白及其基因Prestin mRNA的表达。结果成功建立了放疗早期SNHL Balb/c小鼠模型。照射后第3天组及照射后第7天组小鼠在3、4、6、8、10和12 kHz时的DPOAE幅值较照射前组小鼠均降低,照射后第7天组小鼠的DPOAE幅值在大部分频率上要比照射后第3天组小鼠的DPOAE幅值要低。照射后第3天组及照射后第7天组小鼠的耳蜗Prestin蛋白及其基因Prestin mRNA的表达较照射前组小鼠出现一致性下降,照射后第7天组小鼠的耳蜗Prestin蛋白及其基因Prestin mRNA的表达较照射后第3天组小鼠下调。结论放射线照射早期即可影响小鼠的听觉生理功能。放射线照射早期可使耳蜗外毛细胞Prestin蛋白及其基因Prestin mRNA的表达下调。本研究表明放射线照射导致SNHL可能与放射线照射引起耳蜗外毛细胞Prestin蛋白功能表达的改变有关。