Cu/ZnSOD基因敲除小鼠——研究耳蜗氧化损伤的理想模型

Cu/Zn Superoxide Dismutase Gene Knockout Mice——A Perfect Model for Cochlear Oxidative Damage

目的 确定一个理想的耳蜗氧化损伤模型。方法 对 5只Cu/ZnSOD基因敲除纯合突变 (Cu/ZnSOD无活性 ,Sod1- / - )小鼠和 10只Cu/ZnSOD杂合突变 (5 0 %Cu/ZnSOD失活 ,Sod1+/ - )小鼠及 5只野生小鼠 (Cu/Zn SOD活性正常 ,Sod1+/ +)进行ABR检测及内、外毛细胞计数。应用PCR技术检测Cu/ZnSOD基因敲除小鼠耳蜗mtDNA缺失情况。结果 Cu/ZnSOD基因敲除小鼠耳蜗内外毛细胞大量缺失 (P <0 .0 0 1) ,ABR检测 ,Sod1- / -小鼠ABR阈值在 8,16 ,32kHz及Sod1+/ -小鼠ABR阈值在 16 ,32kHz明显增大 (P <0 .0 0 1)。Cu/ZnSOD基因敲除小鼠耳蜗mtDNA有三种缺失 ,分别为mtDNA 386 7bp、mtDNA 372 6bp及mtDNA 432 6bp缺失。结论 Cu/ZnSOD基因敲除小鼠耳蜗在细胞及分子水平上均表现出受到ROS损伤的改变 ,是一个理想的耳蜗氧化损伤模型。

Objective To determine a perfect model for cochlear oxidative damage.Methods 5 wild-type mice(100% Cu/ZnSOD activity,Sod1+/+)and 15Cu/ZnSOD gene (Cu/Zn superoxide dismutase gene,Sod1)knockout mice including 5 homozygous mutant mice (no measurable Cu/ZnSOD activity,Sod1-/-)and 10 heterozygous mutant mice (50% reduction of Cu/ZnSOD activity,Sod1+/-)were detected by nested polymerase chain reaction (PCR).ABRs were obtained and hair cells were counted.Results Compared to Sod1+/+ mice ,Sod1-/- mice,(8,16,32 kHz) and Sod1+/-(16,32 kHz ) mice exhibited significant threshold elevations and greater hair cells loss ( P <0.001). Three deletions were detectable in cochlear mt DNA of Sod1 knockout mice.They were mtDNA 3867 bp deletion,mtDNA 3726 bp deletion and mtDNA 4236 bp deletion. Conclusion The cochlear of Sod1 gene knockout mice have obvious abnormal changes for ROS damage in cell levels and in molecular levels, it is a perfect model for cochlear oxidative damage.