小鼠耳蜗内外毛细胞胞吞功能的实验研究

Different patterns of endocytosis identified in murine cochlear inner and outer hair cells

目的研究小鼠内外毛细胞胞吞功能的异同,探讨毛细胞胞吞功能与动物听功能之间的关系。方法选择出生后1月龄的正常C57BL/6J小鼠耳蜗基底膜在体外培养,以染料FM1-43为胞吞示踪剂,应用活细胞成像技术观察耳蜗内外毛细胞胞吞现象。结果内毛细胞的胞吞活动主要集中在细胞底部及核下区,而外毛细胞的胞吞活动则主要集中在核上区和外侧壁区。而且,在不同的观察时间点上,内毛细胞对FM1-43的摄入量均显著高于外毛细胞(P<0.05)。结论内毛细胞的胞吞活动集中出现在细胞底部及核下区,说明这种胞吞活动与内毛细胞带状突触的功能密切相关;外毛细胞的胞吞活动主要出现在核上区及细胞外侧壁,表明这种活动更多参与了外毛细胞纤毛及离子通道。内毛细胞比外毛细胞具有更强大的胞吞功能,表明内毛细胞在听功能的发育和维持中发挥着更为关键的作用。

Objective To report different patterns of endocytosis in murine cochlear inner and outer hair cells（IHCs OHCs）. Methods Normal C57BL/6J mice（1 month old） were used to observe different patterns of endocytosis in IHCs and OHCs in vitro using live cell imaging of FM1-43. Results Intense fluorescence density of FM1-43 indicating massive endocytosis activities was identified at the base and blow the nucleus in IHCs. In contrast, major endocytosis activities in OHCs were found at or near the lateral cellular wall and above the nucleus. FM1-43 uptake in IHCs was higher than that in OHCs（P〈0.05）. Conclusion Active endocytosis at or near the basolateral area of the IHC suggests that endocytosis in IHCs may involve ribbon synapse plasticity. Endocytosis activities near the lateral wall and in the supranuclear area in OHC indicate that endocytosis in OHC involves tip-links or iron channels. Higher levels of FM1-43 uptake by IHCs may indicate IHC＇s key roles in hearing development and maintenance.