新霉素致损小鼠听觉上皮后线粒体转录因子B1与毛细胞凋亡的关系

Relationship between mitochondrial transcription factor B1 and hair cell apoptosis after neomycin-induced auditory epithelium damage in mice

目的研究新霉素致损小鼠听觉上皮后线粒体转录因子B1（mitochodnrial transcription factor B1,TFB1M）与听觉上皮毛细胞凋亡的关系。方法每次解剖出20只出生1~2 d的新生ICR小鼠40个耳蜗,使用体外无血清培养法培养听觉上皮,培养后分为正常对照组和新霉素致损组（n=20）,然后在新霉素致损4、12、24 h及24 h洗脱后2 d检测TFB1M在听觉上皮细胞核和线粒体中的表达,以及听觉上皮线粒体膜电位的变化和毛细胞的凋亡。结果新霉素致损4 h后,听觉上皮中圈毛细胞形态完整,其线粒体膜电位开始降低;致损12 h,耳蜗听觉上皮线粒体以及细胞核内的TFB1M表达上调,听觉上皮出现毛细胞底圈、中圈大量毛细胞缺失,未缺失处毛细胞出现线粒体膜电位明显降低;致损24 h中圈、底圈毛细胞基本消失,未检测到线粒体膜电位。洗脱后2 d,TFB1M表达较正常对照组降低,基底膜毛细胞未见进一步缺失。而正常对照组在新霉素致损组相对应的时间点上,离体培养的听觉上皮的毛细胞形态完整,排列整齐,线粒体膜电位无改变。新霉素致损12 h,TFB1M在线粒体和细胞核内的表达较4、24 h,洗脱后2 d都明显（P〈0.01）。结论 TFB1M蛋白质水平的表达上调可能导致线粒体功能异常和毛细胞凋亡。

Objective To observe the relationship between （TFB1M） and hair cell apoptosis of cochlear neurosensory epithelia in epithelium damage in vitro. Methods The cochlea of newborn ICR mitochondrial transcription factor B1 mice with neomycin-induced auditory mice was used for in vitro culture of auditory epithelia, which were divided into a control group and a neomycin expression in the auditory epithelia and mitochondria on 4, 12, and 24 h after damage group. The TFBIM damage and 2 d after elution were detected, and the mitochondrial membrane potential and hair cell apoptosis of cochlear neurosensory epithelia were analyzed. Results On 4 h after neomycin treatment, the shape of hair cells in the middle turn was intact, but the mitochondrial membrane potential began to decrease. On 12 h after neomycin treatment, most of the hair cells in the middle turn and basal turn were lost, and the mitochondrial membrane potential of the remaining hair cells was obviously decreased. Meanwhile, the TFB1M expression was up-regulated significantly in cell nuclei and mitochondria （P 〈 0. 01 ）. On 24 h after neomycin treatment, almost all the hair cells in the middle turn and basal turn were lost, and the mitochondrial membrane potential disappeared. On 2 d after elution, the TFB1M expression was decreased, and the hair cells in the basal membrane were not further lost. In contrast, the hair cells in the control group showed intact shape, regular arrangement and no change of mitochondrial membrane potential. Conclusion The elevated expression of TFB1 M protein may lead to the mitochondrial dysfunction and hair cell apoptosis, which has potential significance in prevention and treatment of neomycin-induced deafness.