传出神经对听力发育早期耳蜗放大功能影响的研究  

The Study on Modulation by the MOC System on Cochlear Amplification at the Early Stage of Hearing Development

作　　者：林国彤 张宇 宋雷 LIN Guotong;ZHANG Yu;SONG Lei(Department of Otolaryngology-Head and Neck Surgery,Shanghai Ninth People's Hospital,Shanghai Jiao Tong University School of Medicine,Shanghai 200011,China)

机构地区：[1]上海交通大学医学院附属第九人民医院耳鼻咽喉头颈外科,上海200011 [2]上海交通大学医学院耳科学研究所 [3]上海市耳鼻疾病转化医学重点实验室

出　　处：《中华耳科学杂志》2024年第5期811-816,共6页Chinese Journal of Otology

基　　金：国家自然科学基金面上项目(81770995)。

摘　　要：目的利用外毛细胞乙酰胆碱受体α9亚基敲除(Knock-out,Chrna9 KO)与功能获得性敲入(Knockin,Chrna9 KI)的点突变小鼠,重点关注Prestin蛋白水平与耳蜗频率编码方面的差异,研究耳蜗传出神经支配对听力发育的影响。方法选取出生后18 d的KO、KI小鼠与其各自对照组,采用听性脑干反应(auditory brainstem responses,ABR)检测听觉功能;通过耳声发射畸变产物(distortion product otoacoustic emission,DPOAE)群延时实验技术评估基底膜上固定频率的编码位置;通过免疫荧光染色分别观察小鼠的传出神经突触与带状突触;全细胞膜片钳技术测量非线性膜电容来评估外毛细胞的功能及Prestin蛋白的表达情况。结果4.0~45.0 kHz的9个频率中,KO Homo组ABR阈值与KO WT组比较,KI Homo组ABR阈值与KI WT组比较,差异均无统计学意义(P>0.05)。22.6、16.0、8.0 kHz频率的90、85、80 dB SPL处,KI Homo组ABR的Ⅰ波波幅高于KI WT组,差异有统计学意义(P<0.05)。KO Homo组各频率、各刺激声的Ⅰ波波幅与KO WT组比较,差异均无统计学意义(P>0.05)。在13 kHz频率上的60 dB SPL,KI Homo组群延时短于KI WT组,差异有统计学意义(P<0.05)。在各频率上,KO Homo组群延时与KO WT组比较,差异均无统计学意义(P>0.05)。KI Homo组传出神经MOC终末计数顶圈第1、3排外毛细胞多于KI WT组,差异有统计学意义(P<0.05),中、底圈外毛细胞与KI WT组比较,差异无统计学意义(P>0.05)。KO Homo组传出神经MOC终末计数顶、中圈第3排外毛细胞数量少于KO WT组,底圈第3排少于KO WT组,差异均有统计学意义(P<0.05)。KI Homo组、KO Homo组外毛细胞非线性膜电容曲线、Qmax值、Vh值、Clin值、Qsp值与KI WT组、KO WT组比较,差异无统计学意义(P>0.05)。结论在听觉发育早期,传出神经支配末梢数量的降低不影响正常的听觉功能、内毛细胞带状突触与外毛细胞电能动性。然而,传出神经调控功能的增强,在不干扰毛细胞发育的情Objective To investigate the impact of cochlear efferent innervation on hearing development,especially Prestin levels and cochlear frequency coding,using acetylcholine receptorα9 subunit knockout(Chrna9 KO)and functional knock-in point-mutant(Chrna9 KI)mice.Methodsα9 KO and KI mice and normal control mice aged p18 received Auditory brainstem responses(ABRs)evaluation.Distortion product otoacoustic emission(DPOAE)group delay was measured to assess frequency place coding on the basilar membrane.The morphology of efferent synapses and ribbon synapses were examined by immunofluorescence staining.Whole-cell patch clamps were used to evaluate the function of outer hair cells(OHCs)and Prestin expression by measuring nonlinear capacitance.Results There were no significant differences in ABR thresholds betweenα9 KO,KI mice and normal controls from 4.0 kHz to 45.0 kHz(P>0.05).ABR waveⅠamplitudes at 22.6,16 and 8 kHz were higher in KI Homo mice than in normal controls at 80-90 dB SPL(P<0.05),but not between KO Homo mice and normal controls(P>0.05).DPOAE group delay was shorter in KI Homo mice than in KI WT mice at 60 dB SPL for f2=13 kHz(left panel)(P<0.05),but not between KO Homo and normal controls(P>0.05).Compared with KI WT mice,the efferent MOC terminals only slightly increased in the first and third rows of OHCs in the apical turn(P<0.05)in KI Homo mice,and showed no difference in the middle and basal turns(P>0.05).The MOC efferent terminals significantly decreased in all three rows of OHCs in the apical and middle turns,and slightly in the third row OHCs in the basal turn in KO Homo mice,compared with KO WT mice(P<0.05).Typical NLC curves for OHCs and derived parameters showed no statistical difference among the three groups(P<0.05).Conclusion Upon completion of peripheral auditory development,reduction of efferent(Chrna9 KO)innervations does not affect hearing thresholds,ribbon synapse counts and OHC electromotility.However,enhanced efferent modulation(Chrna9 KI)may functionally alter traveling wave and frequen

关 键 词：传出神经 外毛细胞 耳蜗放大器 非线性膜电容 PRESTIN 

分 类 号：R764[医药卫生—耳鼻咽喉科]