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目的 探讨神经生长因子 (nerve growth factor,NGF)对大鼠爆震性听力损伤的保护作用。方法 制作强脉冲噪声致聋大鼠模型 30只 ,10只肌肉注射 NGF4周 (爆震前 1周至爆震后 3周 ) ,10只注射等量的生理盐水作对照 ,10只作正常对照 ,测定爆震前后脑干听觉诱发电位 (auditory brain-stem response,ABR)阈值及扫描电镜观察耳蜗毛细胞变化。结果 爆震后 3d NGF组 ABR反应阈恢复较生理盐水组显著快 ,2 1d后 ,NGF组 ABR已恢复正常水平 ,而生理盐水组未能恢复正常水平。扫描电镜示 :爆震后 3h:生理盐水组大鼠外毛细胞静纤毛排列扭曲、倒伏、紊乱、融合及部分缺失 ,NGF组大鼠外毛细胞静纤毛有轻度紊乱及松散 ;爆震后 3d:生理盐水组大鼠外毛细胞静纤毛病变无明显恢复 ,NGF组大鼠外毛细胞静纤毛病变已不明显 ;爆震后 11d:生理盐水组病变减轻 ,NGF组病变基本恢复 ;爆震后 2 1d:生理盐水组病变减轻 ,但有部分病变没有完全恢复 ,NGF组病变完全恢复。结论 NGF能防止受损的毛细胞进一步变性坏死 ,对听觉有明显的保护作用。
Objective To investigate the protective effect of nerve growth factor (NGF) on detonation hearing impairment in rats. Methods Thirty rats with severe impulse noise deafness were made. Ten rats were intramuscularly injected with NGF for 4 weeks (1 week before detonation to 3 weeks after detonation), 10 rats were injected with the same amount of saline as control and 10 rats were used as normal control. Auditory brain-stem response threshold (ABR) before and after detonation and scanning electron microscopy were used to observe changes of cochlear hair cells. Results The ABR response threshold of NGF group was significantly faster than that of saline group after detonation. After 21 days, ABR of NGF group returned to normal level, but normal saline group failed to return to normal level. Scanning electron microscopy showed that at 3h after detonation, the cilia of outer hair cells of rats in normal saline group were distorted, lumbered, disorganized, confused and partly missing. The static cilia of outer hair cells in NGF group were mildly disordered and loose; after detonation 3d: There was no obvious recovery of outer cilia fibrillation in rats in NS group, but no significant changes in outer hair cells in NGF group. On the 11th day after detonation, lesions in NS group were alleviated and lesions in NGF group were recovered. Detonation After 21 days: lesion lesion in the saline group, but some lesions did not fully recover, NGF group lesions completely restored. Conclusion NGF can prevent damaged hair cells from further degeneration and necrosis and have obvious protective effect on hearing.