小鼠耳蜗Na-K-2Cl联合转运子-1的定位及其缺失后的耳蜗组织学改变

Localization of NKCC1 in the Cochlea of Mouse and Histological Changes of the Cochlea of NKCC1-Knockout Mouse

目的探讨耳蜗钾循环途径中Na-K-2Cl联合转运子-1(Na-K-2Clcotransporter-1,NKCC1)在小鼠耳蜗的分布及NKCC1基因敲除后耳蜗组织学的改变。方法选用10只C57BL/6J小鼠((NCKK1+/+)和5只NKCC1基因敲除小鼠(NKCC1-/-),应用听性脑干反应(auditorybrainstemresponse,ABR)分别检测NCKK1+/+小鼠和NKCC1-/-小鼠的听功能,采用免疫组织化学及甲苯胺蓝染色的方法观察NKCC1在NCKK1+/+小鼠耳蜗的定位及NKCC1-/-小鼠耳蜗组织学的变化。结果NCKK1+/+小鼠ABR平均阈值为31±5.36dBSPL,而NKCC1-/-小鼠听力完全丧失。NKCC1在NCKK1+/+型小鼠耳蜗主要分布在血管纹上皮(边缘细胞)和螺旋韧带下部纤维细胞,在纹上区和螺旋缘处的纤维细胞中也有适度表达;NKCC1-/-小鼠耳蜗前庭膜塌陷,中阶完全消失,内毛细胞、外毛细胞、支持细胞减少,Corti隧道消失。结论NKCC1在耳蜗的定位与耳蜗钾循环密切相关,NKCC1缺失会导致耳蜗正常结构的破坏,继而影响耳蜗生理功能。

Objective To investigate the localization of Na-K-2Cl cotransporter-1 （NKCC1） in the cochlea of mouse and the histological changes of the cochlea of NKCC1 - knockout mouse. Methods Auditory function of NKCC1 - knockout mouse was measured by auditory brainstem response （ABR）. The localization of NKCC1 in the cochlea of wild type mouse was detected by immunohistochemistry and histological changes of the cochlea of NKCC1 - knockout mouse were observed with toluidine blue staining, Results NKCC1 - knockout mouse lost its hearing completely. In the cochlea of wild type mouse cochlea, NKCC1 was expressed mainly in the stria vascularis epithelium （marginal cells） and the fibrocytes in the inferior portion of the spiral ligament. Subpopulation of the fibrocytes in the suprastrial region and the limbus were moderately immunoreactive. In the cochlea of NKCC1 - knockout mouse, Reissner＇ s membrane collapsed and scala media disappeared, compounded by the loss of inner hair cells, outer hair cells and the support cells. The tunnel of Corti was absent as well. Conclusion The localization of NKCC1 in the cochlea is highly correlative with potassium recycling in cochlea. Lack of NKCC1 lead to the destruction of structures of the cochlea, and influence the physiological functions of the cochlea subsequently.