年龄相关听力损失DBA/2J小鼠耳蜗毛细胞马达蛋白-prestin表达下调与耳聋的关系  

Down-Regulated Prestin Expression in Cochlear Outer Hair Cells in DBA/2J Mice with Age-related Hearing Loss

作　　者：李胜利[1] 武坤毅 任晓勇[2] 翟所强(审核人) LI Shengli;WU Kunyi;REN Xiaoyong(Scientific Research Centre,Second Hospital of Xi’an Jiaotong University,Xi’an 710004,China;DepatmentofOtorhinolaryngologyHeadandNeckSurgery,SecondHospitalofXi’anJiaotongUniversity,Xi’an710004,China)

机构地区：[1]西安交通大学第二附属医院科研中心实验室,西安710004 [2]西安交通大学第二附属医院耳鼻咽喉头颈外科,西安710004 [3]不详

出　　处：《中华耳科学杂志》2018年第4期562-569,共8页Chinese Journal of Otology

基　　金：国家自然科学基金面上项目(81170922),陕西省自然科学基础研究项目(2017JM8097),西安交通大学第二附属医院青年项目(YJ(QN)201622)。

摘　　要：目的老年性聋亦称年龄相关性听力损失,主要是听觉器官退行性改变所致。许多研究已证明prestin与内耳的声强感觉和频率分辨密切相关,我们推测老年性聋与耳蜗毛细胞prestin的表达具有一定的关系,本研究探讨prestin在耳蜗毛细胞表达的改变在老年性聋发病机制的作用,期望为老年性聋的防治提供依据。方法采用快速老化DBA/2J小鼠,对4,8,16和32周龄(W)的48只小鼠进行听觉脑干诱发电位(ABR)测定。耳蜗快速取材固定,全耳蜗铺片行毛细胞记数,免疫组化荧光标记prestin在耳蜗毛细胞的表达,激光共聚焦显微镜进行观察。Western biotting进行prestin蛋白定量分析。结果耳蜗毛细胞记数结果可见4周龄DBA/2J小鼠的耳蜗基底回有56.35%外毛细胞(outer hair cells,OHCs)消失,中回仅有个别消失,顶回有11.07%的OHCs消失;到8W时,DBA/2J小鼠的耳蜗基底回有97.85%OHCs消失,中回12.7%OHCs消失,顶回近20%的OHCs消失;16周龄时基底回OHCs完全消失,中回有80%的消失,顶回有30%的消失;DBA/2J老化小鼠到32W时,基底回OHCs已全部消失,中回也基本消失殆尽达99.5%,顶回的OHCs有80%左右消失。同时,在4W时OHCs prestin的表达从基底回到顶回均有较强的表达;到8W时耳蜗OHCs prestin的表达整体下降,与4W时相比表达下降十分显著(P≤0.01);到16W时,耳蜗OHCsprestin的表达下降更明显。与其相对应的是ABR反应阈值随年龄增长显著升高。Prestin表达与细胞核显示同时存在,OHCs消失同时prestin表达亦消失。结论本实验结果证明,年龄相关听力损失DBA/2J小鼠的耳蜗OHCsprestin表达随听力损失而正向表达下降,毛细胞消失部位有prestin表达的消失。说明prestin表达下降是导致老年性聋的重要因素之一,其结果可能是导致老年性聋发生的分子机制之一。Objective Age-related hearing loss(AHL),also known as presbycusis,is the most common form of hearing loss and the predominant age-related neurodegenerative disease.AHL is thought to be the irreversible loss of cochlear hair cells in the inner ear,with this being well documented in both aging humans and animal models.Prestin,an outer hair cells(OHCs)-specific molecular motor protein,is required for active mechanical amplification functions.In this paper we report the presumable correlations between prestin and AHL.The present study was designed to investigate prestin expression on the OHC of DBA/2J mice from 4 weeks to 32 weeks.Methods Auditory function was as-sessed by auditory brainstem response(ABRs).Morphological changes were examined by immunofluorescence and cochleograms.The intensity of prestin expression in the cochlea for was measured as protein density by Western blotting.Results From 8 weeks to 32 weeks ABR thresholds gradually elevated from normal(approximately 25 dB SPL)to approximately 40 dB SPL.However,by 32 weeks,the threshold elevation was approximately 80 dB SPL,parallel with the pattern of hair cell loss noted in the basal region of the cochlea.The number of OHCs in all 4 weeks-old animals were normal in the apical and middle turns,although showing loss of a few OHCs in the basal turn.In 8 weeks-old animals,there was moderate OHC loss(>15%)in the middle turn,and severe loss(>80%)in the basal turn.In 16 weeks-old animals,the apical turn showed moderate OHCs loss(>20%),while the middle and basal turns showed severe loss(>80%).In 32 weeks-old animals,only 20%of OHCs were present in the apical turn,and almost all OHCs were lost in the middle and basal turns.The relative prestin fluorescence intensity at 4,8,16 and 32 weeks demonstrated a progressive decrease following the hearing loss.Conclusions Age-related prestin expression decrease was observed in DBA/2J mice.The prestin expression seems to disappear at locations of OHS loss,indicating that prestin down-regulation is a crucial factor leading to

关 键 词：老年性聋 耳蜗 毛细胞 PRESTIN 

分 类 号：R764[医药卫生—耳鼻咽喉科]