卡那霉素联合呋塞米致聋小鼠耳蜗螺旋神经节细胞的退化变性及其EFR3A蛋白的表达

The spiral ganglion degeneration and the expression of EFR3A in the cochlea of the deaf mice induced by co-administration of kanamycin and furosemide

目的 观察小鼠耳毒性药物损伤毛细胞后耳蜗螺旋神经节细胞的退化变性以及该过程中EFR3A蛋白的表达变化.方法 48只8周龄C57BL/6J小鼠采用卡那霉素联合呋塞米单次注射给药破坏耳蜗毛细胞,给药后1、5、15、30、60 d时采用免疫荧光染色、半薄切片甲苯胺蓝染色以及透射电镜等手段观察耳蜗毛细胞损伤和螺旋神经节的退化变性程度,同时通过免疫荧光和蛋白印迹等技术检测螺旋神经节细胞退化变性过程中EFR3A蛋白的表达变化.结果 联合应用卡那霉素和呋塞米可明显损伤C57BL/6J小鼠耳蜗毛细胞,毛细胞破坏后,螺旋神经节细胞出现退化变性.螺旋神经节细胞超微结构的损伤改变最早开始于给药后5d,其数量下降开始于给药后15 d.与对照组相比,EFR3A蛋白表达的明显增强出现在给药后5d,给药后15 d时其表达下降并接近正常,之后未再出现明显变化.结论 小鼠耳蜗毛细胞损伤后螺旋神经节细胞发生退化变性,其EFR3A蛋白表达升高,两者在时间上高度重合,提示EFR3A蛋白在耳蜗毛细胞破坏后螺旋神经节细胞的退化变性过程中可能发挥一定作用.

Objective To investigate the spiral ganglion degeneration and the expression of EFR3A in the cochlea of the deaf mice induced by co-administration of kanamycin and furosemide.Methods Eight weeks old C57BL/6J mice were administered with a single dose of kanamycin followed by furosemide,then fluorescent immunohistochemistry staining and transmission electron microscopy were applied to observe the SGNs＇ degeneration process and extent characteristics at 1,5,15,30 and 60 days following treatment.We detected the expression of EFR3A during the degeneration of SGNs via fluorescent immunohistochemistry and western blotting.Results Co-administration of kanamycin and furosemide quickly induced cochlear hair cell death in mice,and then caused progressive degeneration of SGNs.Our results showed that the abnormal morphology of SGNs occurredat day 5 following administration,and the number of SGNs began to decrease at day 15.Compared to the control group,it was found the remarkable increase of the EFR3A protein at the fifth day after co-administration,then decreased to the nearly normal at 15 days following treatment,and no further significant changes thereafter.Conclusion The changes of the EFR3A protein expression in the spiral ganglion of the cochlea in mice are coincidence with the time of the SGNs degeneration to happen,which imply that EFR3A may play an important role in the occurrence of the SGNs＇ degeneration in the cochlea in mice following hair cells loss.