miR-124a对2型糖尿病小鼠胰腺组织氧化应激损伤的影响

Effect of miR-124a on oxidative stress injury of pancreatic tissue in type 2 diabetic mice

目的探讨miR-124a对2型糖尿病(diabetes mellitus type 2,T2DM)小鼠的胰腺组织氧化应激损伤和β细胞功能的影响。方法将野生型C57BL/6和miR-124a低表达的C57BL/6小鼠分别随机分成2组:野生空白组(WT Con)、miR-124a^(+/-)空白组(miR-124a^(+/-)Con)、野生模型组(WT Mod)、miR-124a^(+/-)模型组(miR-124a^(+/-)Mod)。采用高脂高糖饮食联合尾静脉注射链脲佐菌素构建T2DM小鼠模型(空腹血糖≥11.1 mmol·L^(-1)),建模成功后继续高脂高糖饮食饲养8周。检测各组小鼠的体质量、FBG及INS变化。HE染色和透射电镜观察胰腺组织的病理学变化及超微结构变化。ELISA法检测小鼠血清的氧化应激因子ROS、·OH的含量及抗氧化酶Mn-SOD、CAT的活性。ELISA法检测小鼠胰腺组织的ComplexⅡ、Ⅲ、Ⅳ的活性和ATP含量。结果与WT Con对比,miR-124a^(+/-)Con小鼠血清ROS、·OH和胰腺组织的ATP含量降低(P<0.05),miR-124a^(+/-)Mod小鼠的FBG升高,INS含量降低,血清Mn-SOD和CAT活性下降,胰腺组织的ATP含量和ComplexⅡ、Ⅲ和Ⅳ活性降低(P<0.05)。与WT Mod对比,miR-124a^(+/-)Mod小鼠的FBG和血清ROS、·OH降低(P<0.05),胰岛形态好转,INS含量、Mn-SOD、CAT活性和胰腺组织的ATP含量、Complex Ⅱ、Ⅲ和Ⅳ活性升高(P<0.05)。结论降低小鼠miR-124a表达可降低T2DM小鼠FBG,胰腺病理损伤得到缓解,其作用机理可能为提高胰腺组织的抗氧化能力,减少氧化应激对β细胞的损伤有关。

Aim To investigate the effect of miR-124a on oxidative stress injury and β-cell function of pancreas in type 2 diabetic mice.Methods The wild-type C57BL/6 mice and the C57BL/6 mice with low expression of miR-124a were randomly divided into two groups,namely wild-type control(WT Con),miR-124a^(+/-)control(miR-124a^(+/-)Con),wild-type model(WT Mod),and miR-124a^(+/-)model(miR-124a^(+/-)Mod).The T2DM mouse model(FBG≥11.1 mmol·L^(-1))was established by high-fat and high-sugar diet combined with the tail vein injection of streptozotocin,after the mice were fed with high-fat and high-glucose diet for eight weeks.The levels of weight,FBG and INS were detected.HE staining and transmission electron microscopy were used to observe the pathological and ultrastructural changes of pancreatic tissue.The serum contents of ROS,·OH and ATP level of in pancreas,the activities of Mn-SOD,CAT in serum and Complex Ⅱ,Ⅲ,Ⅳ in pancreas mitochondria were detected by ELISA kits.Results Compared with WT Con,the serum levels of ROS,·OH and pancreatic ATP content were significantly reduced in miR-124a^(+/-)Con group(P<0.05).In miR-124a^(+/-)Mod group,the FBG level was obviously raised,and decreased levels and activities were observed in INS,Mn-SOD and CAT,as well as the level of ATP and the activities of ComplexⅡ,ⅢandⅣin pancreas mitochondria(P<0.05).Compared with WT Mod,the FBG in miR-124a^(+/-)Mod was significantly reduced,the islet morphology and atrophy were alleviated,the activities of CAT,Mn-SOD and Complex Ⅱ,Ⅲ,Ⅳ were obviously enhanced(P<0.05),so was ATP level,whereas the ROS and·OH contents decreased(P<0.05).Conclusions The mechanism of the down-regulation of miR-124a expression on reducing FBG and ROS in T2DM may be related to the improvement of antioxidant capacity and the reduction of the oxidative stress injury in β-cells,achieving the protective effects on pancreatic tissues.