目的：研究年龄相关性听力损失过程中听力阈值变化与耳蜗内毛细胞带状突触标记物数量之间的关系。方法应用C57BL/6J小鼠进行本研究。在本研究中，对鼠龄为1、2、4、6和12个月的C57BL/6J小鼠分别进行ABR阈值检测分析(Click&Tone burst)。对被检测小鼠的耳蜗基底膜标本进行突触前特异蛋白RIBEYE/CtBP2进行免疫荧光标记，采用激光共聚焦观察结合三维重建的方法来计数突触标记物(RIBEYE/CtBP2)的数量并进行统计学分析。结果小鼠的ABR阈值从鼠龄4个月时开始出现显著抬高(P<0.05)，以后在鼠龄为6和12个月时抬高更加明显。在频率分布上，这种阈值的抬高在高频区域(8KHz&16KHz)表现的最为明显。同时，本研究发现标记物的数量和ABR阈值的变化呈现一致性的改变：突触标记物数量也在4个月时开始出现减少(P<0.05)，且随着鼠龄的增加数量减少更加明显。这种数量减少的表现在高频区域(8KHz&16KHz)表现得尤为显著(P<0.01)。在听力减退的早期阶段(鼠龄4-6个月)，小鼠毛细胞，尤其是内毛细胞数量并未现明显的减少。结论老年性听力损失和耳蜗带状突触的数量改变密切相关，突触数量的减少可能是导致年龄相关性听力损失的一个重要因素。%Objective To study possible correlations between the number of cochlear ribbon synapses and elevation of ABR thresholds related to aging. Methods C57BL/6J mice were utilized to mimic age related hearing loss in this study. ABR threshold was examined at 1M, 2M, 4M, 6M, and 12M respectively. Immunostaining combined with laser confocal mi-croscopy was used to identify RIBEYE/CtBP2, a specific pre-synaptic component of cochlear ribbon synapses, and the num-ber of labeling synaptic ribbons was calculated using the 3D max 8.0 software. Results ABR threshold elevation was first found after 4M (P<0.05), and continued to increase at 6M and 12M (P<0.05). Further, the most significant ABR threshold el-evation at a given age was identified at high frequencies (P<0.01, 8 and 16 kHz). Correspondingly, the reduction of labeling ribbon synapses was noticed along with ABR threshold shifts as the mice aged, also with more labeling synapses reduction in the high frequency regions (P<0.01, 8 and 16 kHz). However, we did not find significant loss of inner hair cells in during the same aging period. Conclusion There is faithful correlation between hearing threshold shifts and reduction of labeling synaptic ribbons, with most reduction occurring in high frequency regions. This study shows that the loss of ribbon synapses may contribute to age-related hearing loss.
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