哇巴因对大鼠耳蜗螺旋神经节细胞的损伤

Detrimental effects of ouabain on cochlear spiral ganglion cells in rats

目的观察哇巴因（ouabain）对sD大鼠耳蜗螺旋神经节细胞（spiralganglioncell，SGC）的损伤。方法75只雄性sD大鼠随机数字表法分为5组，除健康对照组外，其余4组经耳蜗鼓阶钻孔分别给予0．01、0．02、0．05mmol／L哇巴因以及生理盐水。术后7d行畸变产物耳声发射（DPOAE）及听陡脑干反应（ABR）测试；大鼠处死后取耳蜗组织，通过免疫组化和透射电镜观察耳蜗SGC形态学变化。体外分离培养孕14d胎鼠SGC，加入1×10“mmol／L哇巴因，通过光镜和扫描电镜观察哇巴因对离体培养SGC的损伤。结果鼓阶注入哇巴因后，大鼠DPOAE无明显改变，各组之间不同频率DPOAE幅值差异均无统计学意义（P值均〉0．05）。耳蜗鼓阶注入哇巴因后，大鼠ABR反应阈升高，且升高幅度随着哇巴因浓度的增加而加大；哇巴因组大鼠ABR阈值与生理盐水组及健康对照组相比，差异具有统计学意义（P值均〈0．05）。电镜下哇巴因组大鼠SGC发生退行性改变，细胞器结构破坏，核膜溶解，神经髓鞘崩解、空泡化。哇巴因同样可导致离体培养SGC的损伤，胞体皱缩、变小，突起缩短、断裂，细胞结构破坏。结论无论是在体还是体外细胞培养，哇巴因均可确切造成SGC损伤。

Objective To investigate the detrimental effects of ouabain, in vivo and in vitro on cochlear spiral ganglion cells （SGC）. Methods Seventy-five male SD rats were randomly divided into five groups. In addition to the normal control group, rats in other four groups received 0. 01,0. 02, 0. 05 mmol/L of ouabain or saline through cochlear scala tympani drilling. Seven days after surgery, the hearing threshold was measured by distortion product otoacoustic emissions （DPOAE） and auditory brainstem response （ABR） in rats. In the in vitro study, SGC were isolated from the SD rats （El4） and treated with 1 x 10-s mmol/L of ouabain. The damaged of SGC were detected after ouabain treatment using immunohistochemistry, transmission electron microscope and scanning electron microscope in vitro. Results After administration of ouabain, DPOAE did not change significantly. No significant difference in the amplitude of DPOAE could be observed among all the groups（ P 〉0. 05）. Compared with saline and normal control, ABR threshold significantly increased in the onabain treated groups （P 〈 0. 05 ）, which correlated well with the concentrations of ouabain. Electron microscopy showed that after treated with ouabain, SGC presented degenerative changes, including the collapse of organelle structures, the karyotheca dissolving, and the myelin sheath disintegrating. Conclusion Ouabain can damage SGC, either in the in vivo or in vitro conditions.