神经生长因子对大鼠爆震性听力损伤的保护作用

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l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3dNGF组ABR反应阈恢复较生理盐水组显著快，2ld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lld：生理盐水组病变减轻，NGF组病变基本恢复；爆震后2ld：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。

Protective effects of nerve growth factor on blast exposure hearing damage in Wistar rats

Objective To study the protective effects of nerve growth factor(NGF) on blast exposure hearing damage in Wistar rats.Methods Rats were given either NGF (NGF group) or 0.9% sodium chloride(NS group)for 4 weeks from 7 days before blast exposure to 21 days after blast exposure.Rats in the control group were given neither medicine nor noise exposure.ABR threshold shifts were tested in the rats before and after the blast exposure,and cochlear morphological changes were examined with scanning electron microscopy.Results The ABR threshold shifts in the NGF group 3 hurs,3 days,11 days,and 21 days after the blast exposure were significantly smaller than those in the NS group.No permanent threshold shifts was seen in any of the NGF group rats.Scanning electron microscopy indicate that pathological changes of the outer hair cells stereocilia in the NGF group 3 hours after blast exposure were less obvious than those in the NS group.And on day,21,the stereocilia appeared perfectly normal and well defined in the NGF group,where as there still remained some stereocilia abnormalities in the NS group.Conclusions NGF can protect cochlear hair cells against blast exposure by decreasing degeneration and necrosis.