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目的观察日常生活可遇低强度噪声多次暴露对豚鼠耳蜗带状体突触的损失和恢复,以及对听觉功能的影响。方法对豚鼠行95 d B声压级白噪声环境下4 h/d暴露,连续暴露7 d,于噪声后1 d、1周、1个月分组行听力学检查,并与对照组动物比较(每组10只),以免疫荧光法双标法对突触前膜Ctbp2和突触后膜PSD95进行标记并计数。结果长时程、低强度噪声暴露后听觉脑干诱发电位阈值提高(P<0.05),豚鼠内毛细胞排布、形态、数量均无明显改变,但内毛细胞带状突触数量有明显减少(P<0.05)并有不完全恢复。结论 “安全剂量”低强度噪声多次暴露后可造成可逆听觉阈值升高,伴随内毛细胞带状体突触的明显减少和不完全恢复。
Objective To observe the loss and recovery of synapses in guinea pig cochlear striae as well as their effects on auditory function in multiple daily exposure to low intensity noise. Methods The guinea pigs exposed to white noise of 95 d B sound pressure level for 4 h / d were exposed for 7 days. The rats were subjected to audiometry at 1, 1 and 1 month after noise, and compared with the control animals 10 in each group). The presynaptic membrane Ctbp2 and postsynaptic membrane PSD95 were labeled by double immunofluorescence method and counted. Results After long-term and low-intensity noise exposure, the auditory threshold of auditory brainstem response increased (P <0.05). There was no significant change in the arrangement, shape and number of hair cells in guinea pigs, however, the number of ribbon synapses in inner hair cells decreased significantly (P <0.05) and incomplete recovery. CONCLUSIONS: Repeated exposure of “safe dose” low intensity noise can cause a reversible increase in auditory threshold accompanied with a significant reduction and incomplete recovery of synapses in the inner hair cells.