感音神经性聋小鼠耳蜗外侧壁形态及功能的改变

Morphological and functional responses of cochlear lateral wall following sensorineural hearing loss in mouse

目的:探讨感音神经性聋发生后小鼠耳蜗外侧壁形态和功能的改变。方法:选用3-4周龄的CBA/J小鼠为实验对象,联合应用卡那霉素及呋塞米致聋。在给药后0.5 d、1 d、2 d、7 d、28 d及112 d监测耳蜗内电位(EP)的改变;应用HE染色、免疫化学和透射电镜方法检测耳蜗外侧壁形态以及2种K+转运蛋白NKCC1和α2Na,K-ATPase的变化。结果:序贯应用卡那霉素及呋塞米后0.5 d小鼠EP开始下降,至1 d进行性下降,至2 d完全恢复正常并在随后长时期保持稳定。HE染色显示毛细胞损失和耳蜗外侧壁萎缩是主要病理改变。免疫化学结果表明耳蜗外侧壁NKCC1和α2Na,K-ATPase蛋白表达明显下降。透射电镜结果显示血管纹厚度在致聋后进行性下降,主要为边缘细胞萎缩造成。结论:萎缩后的耳蜗外侧壁在毛细胞严重缺失的情况下仍然可以保证EP的正常维持。

AIM：To investigate the morphological and functional responses of the cochlear lateral wall following sensorineural hearing loss in mouse.METHODS： CBA/J mice of 3-4 weeks old were deafened by co-administration of kanamycin and furosemide.The endocochlear potential（EP） were measured at 0.5,1,2,7,28 and 112 days after administration of the drugs.The morphological changes of the lateral wall,the expression of NKCC1 and α2 Na,K-ATPase were assessed and verified by histological examination.RESULTS： The EP displayed a significant decline 12 h after treatment,followed by complete recovery on the 2nd day.Then the EP maintained at near normal level in the animals deafened for a period up to 112 days.Loss of the hair cells and atrophy of the lateral wall were the main pathological changes observed.The expression of NKCC1 and α2 Na,K-ATPase in the lateral wall was significantly reduced after a long-term deafening.There was also a significant and progressive decrease in stria vascularis thickness while the major cause appeared predominantly to be a reduction in the volume of the marginal cells.CONCLUSION： Atrophic lateral wall is capable of maintaining a normal EP under the condition of severe hair cell loss.