协和医学杂志

2012, v.3(02) 148-153

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小鼠耳蜗神经及其与内毛细胞突触后谷氨酸受体发育的特点
Development of Auditory Nerves and Postsynaptic Glutamate Receptors (GlutR2/R3) of Mouse Cochlea

杨华;甘霖;陈晓巍;高志强;
YANG Hua1,GAN Lin2,CHEN Xiao-wei1,GAO Zhi-qiang1 1Department of Otorhinolaryngology,Peking Union Medical College Hospital,Chinese Academy of Medical Sciences & Peking Union Medical College,Beijing 100730,China 2University of Rochester Medical Center,Rochester,NY 14642,USA

摘要(Abstract):

目的了解小鼠耳蜗神经发育特点及耳蜗内毛细胞与蜗神经突触后谷氨酸受体发育的时间特点。方法采用免疫组化方法 ,通过共聚焦显微镜观察和记录不同发育阶段小鼠前庭耳蜗神经/耳蜗神经纤维及内毛细胞与蜗神经纤维突触后谷氨酸受体(glutamate receptor,GluR)2和3的发育与分布。结果胚胎9.5d(E9.5)在听囊听上皮、前庭耳蜗神经核团及面神经核团中即可观察到NeuroD高信号表达;L1在面神经核团亦开始有明显表达。至E12.5,L1和Tuj1在前庭耳蜗神经核团和面神经核团均有强信号表达,表达位置基本重合;在听上皮组织可观察到明确的Tuj1信号,显示听上皮与前庭耳蜗神经核团间神经纤维联系已建立。E12.5,还可发现前庭耳蜗神经核团和神经管核团间神经纤维,显示前庭耳蜗神经中枢方向的神经纤维已经发育。E13.5,耳蜗内可见L1和Tuj1在螺旋神经核团及神经纤维结构中高信号表达,提示内耳分化为耳蜗和前庭两个部分后传入神经进一步发育。E16.5,自螺旋神经节至毛细胞的神经纤维清晰可见,L1和Tuj1高信号表达;同时可以看到耳蜗内毛细胞周围有大量神经纤维分布;但内毛细胞周围未见明显谷氨酸受体(GluR2/R3)表达。E18.5可以看到耳蜗内毛细胞周围大量神经纤维分布,神经纤维末梢有高信号GluR2/R3表达。出生后1d,内毛细胞底部周围突触后GluR2/R3信号更为明显,并为L1标记的神经纤维所包裹,GluR2/R3与L1信号共标记,主要位于靠近内毛细胞底部的神经纤维末梢。结论小鼠耳蜗神经元与感觉上皮和中枢神经系统在胚胎发育较早期即建立了纤维联系,神经纤维支配的建立早于内毛细胞成熟;而内毛细胞与蜗神经纤维的突触联系在胚胎发育晚期及出生后才逐渐发育和完善。
Objective To study the development of auditory nerves and postsynaptic glutamate receptors (GlutR2/R3) between inner hair cells and auditory nerve fibers of mouse cochlea.Methods The development and distribution of auditory nerves and postsynaptic glutamate receptors (GlutR2/R3) between inner hair cells and auditory nerve fibers of mouse cochlea were observed by immunohistochemical techniques in the embryos and newborns of mice with C57BL/6J and 129S6 mixed genetic background.Results At 9.5-day embryo (E9.5) of mouse inner ear,high signals of NeuroD were detected on otic epithelia,vestibulocochlear ganglia,and facial ganglia.Innervation connections between vestibulocochlear ganglia and otic epithelia and between vestibulocochlear ganglia and neural tubes were observed at stage as early as E12.5.At E13.5,highly expressed signals of L1 and Tuj1 were detected in spiral ganglia and nerve fibers in cochlea,which suggested that efferent fibers further developed after the division of inner ear into cochlear and vestibular parts.At E16.5,nerve fibers connecting the spiral ganglia and hair cells were clearly visible.L1 and Tuj1 were highly expressed and rich clusters of nerve fibers were visible around the inner hair cells.However,GlutR2/R3 signals were not detected until E18.5 between inner hair cells and auditory nerve fibers and became stronger at P1.Postsynaptic GlutR2/R3 signals were focused around the bottom of inner hair cells.Conclusions The auditory nerves appear to establish fiber connections with the sensory epithelium and central nervous system as early as the period of embryo development.The establishment of nerve fiber domination is earlier than the maturation of inner hair cells.The synapse connection between the inner hair cells and auditory nerves gradually develops at the later stages of gestation and after birth.

关键词(KeyWords): 耳蜗神经;毛细胞;谷氨酸;受体
auditory nerve;hair cell;glutamate;receptor

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基金项目(Foundation): 北京市科技新星计划(2006B53)

作者(Author): 杨华;甘霖;陈晓巍;高志强;
YANG Hua1,GAN Lin2,CHEN Xiao-wei1,GAO Zhi-qiang1 1Department of Otorhinolaryngology,Peking Union Medical College Hospital,Chinese Academy of Medical Sciences & Peking Union Medical College,Beijing 100730,China 2University of Rochester Medical Center,Rochester,NY 14642,USA

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