NT-3耳蜗局部转染对抗噪声所介导的Ribbon突触损伤

Noise-induced hearing loss (NIHL) plays a significant role in sensorinerual hearing loss (SNHL), one of the most common neurological disorders. Early researches illustrated that the Ribbon synapse located below inner hair cell encountered severe lesion followed by partial recovery after noise exposure of specific level, which could partly explain the contradiction between permanent hearing loss and perfect recovery of cilia of hair cell. Recently findings revealed the lesion of Ribbon synapse after noise exposure was concerned with calcium overload in inner hair cell. Inhibiting calcium overload in inner hair cell, by which neural excitotoxicity could be released, is believed to be an effective way to protect against lesion of synapse induced via noise. It was reported that neurotrophin-3 (NT-3) could inhibit calcium overload in inner hair cell after noise exposure effectively. Based on these findings and the experiences of cochlear transfection in our laboratory as well as the preliminary experiment of the transfection of NT-3 gene linked to mutant AAV vector in cochlea, the hypothesis that it would be an appropriate way to treat the lesion of synapse mediated by noise through gene therapy is raised. In this project, we plan to confirm synapse lesion after noise exposure initially, subsequently explore the possibility of the protection of NT-3 gene linked to mutant AAV carrier against the lesion mediated by noise.

一定强度的噪声暴露可引起永久性听力损伤，而耳蜗毛细胞纤毛却呈现出近似完美的修复，机制不明。研究发现噪声暴露后内毛细胞下方的Ribbon突触严重损伤且只能部分修复，这或可解释噪声暴露后永久性听觉功能受损与毛细胞纤毛完美修复的矛盾。新近研究发现噪声暴露后Ribbon突触的损伤与内毛细胞钙超载有关。抑制内毛细胞钙超载，或可拮抗噪声性突触损伤。已知神经营养因子-3（NT-3）能够抑制噪声暴露后的内毛细胞钙超载，结合我们实验室在内耳局部基因转染方面的研究基础，以及预实验结果证实的使用酪氨酸残基变异的腺相关病毒搭载NT-3耳蜗转染能够实现NT-3在内毛细胞高效的表达，我们提出通过耳蜗局部基因转染抑制噪声性突触损伤，促进突触修复的假说。本课题拟首先确认噪声暴露下Ribbon突触的损伤情况，在此基础上探索使用mutant AAV搭载NT-3抑制噪声性Ribbon突触损伤,减轻噪声性听力损害的可能性。

该项研究探索了由酪氨酸变异腺相关病毒（mutant AAV）搭载的神经营养因子-3基因（NT-3）在耳蜗局部转染抑制噪声性Ribbon突触损伤，减轻噪声性听力损害的可能性。本研究首先从听力学及形态学方面验证了亚临床噪声对成年豚鼠的Ribbon突触的声损伤，进而探索了NT-3基因在耳蜗毛细胞中的表达情况，最终观察到了耳蜗局部表达的NT-3基因对噪声性Ribbon突触损伤有限的保护作用，为进一步探索亚临床噪声导致声损伤的防治奠定了基础。