钙蛋白酶与内毛细胞带状突触噪声损伤的相关性研究

Correlation Study of Calpain and Noise-induced Cochlear Synaptopathy in Inner Hair Cells

蔡瑞捷;刘宏超;周卫军;刘辉辉;吴皓

1:上海交通大学附属第九人民医院耳鼻咽喉头颈外科

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

摘要
目的 通过比较噪声暴露后基底膜不同区域内毛细胞(IHCs)带状突触损伤差异,探讨带状突触损伤易感性的相关因素。方法 将28只C57BL/6J雄性小鼠随机分为噪声暴露组和对照组,每组14只。噪声暴露组小鼠给予强度103 dB SPL、频率2~20 kHz、持续2 h的宽带噪声暴露,对照组小鼠则饲养于安静环境中。噪声暴露前及噪声暴露后第一天进行ABR测试及毛细胞带状突触免疫荧光染色实验。使用全细胞膜片钳技术比较不同区域IHCs的钙离子流入。通过免疫荧光染色比较噪声暴露后的耳蜗基底膜顶回、中回、底回IHCs钙蛋白酶(Calpain)表达水平,并用蛋白质印迹实验验证钙蛋白酶对IHCs带状突触蛋白CtBP2的损伤作用。结果 噪声暴露后一天,噪声暴露组在11.3、16.0、22.6、32.0 kHz的ABR阈值较对照组显著上升(均为P<0.001),中回、底回IHCs带状突触数量明显减少(P<0.05)。全细胞膜片钳实验结果表明耳蜗基底膜中回IHCs有较多的钙离子通道(P<0.01),但其单通道电流较小(P<0.01),顶回、中回IHCs钙离子通道开放率无显著差异(P>0.05)。噪声暴露后,耳蜗基底膜中回、底回IHCs的Calpain表达水平显著高于顶回(P<0.001),蛋白质印迹实验结果表明Calpain以钙离子依赖的方式降解带状突触蛋白CtBP2。结论 钙蛋白酶是基底膜高频区内毛细胞带状突触噪声损伤易感的重要因素。
关键词
噪声性听力损失;带状突触;钙离子;钙蛋白酶
基金项目(Foundation):
国家自然科学基金青年科学基金(82101211);; 上海市耳鼻疾病转化医学重点实验室项目(14DZ2260300);; 上海市科委“科技创新行动计划”基础研究领域项目(21JC1404000);; 上海市临床重点专科建设项目-耳鼻喉(shslczdzk00802)
作者
蔡瑞捷;刘宏超;周卫军;刘辉辉;吴皓
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