不同力学刺激对T2DM小鼠骨中TGF-β/Smad途径及骨形成的影响

Effect of Different Mechanical Stimulation on the TGF-β/Smad Pathway and Bone Formation in Type 2 Diabetes Mellitic Mice

目的:探究不同力学刺激对T2DM小鼠骨中TGF-β/Smad途径相关分子表达及骨形成的影响。方法:通过6周高脂膳食和注射STZ进行T2DM小鼠造模,2周后随机分为T2DM对照组(TC)、T2DM游泳组(TS)和T2DM下坡跑组(TD),另设正常对照组(ZC)。利用8周游泳和下坡跑对TS和TD组小鼠进行干预。利用RT-PCR等技术方法对细胞因子mRNA和蛋白表达、OB骨形成能力、股骨BMD等进行检测。结果:与ZC组相比,TC组TGF-β、Smad2/3/4、Runx2和Osx的mRNA表达及p-Smad2/3和Smad4蛋白表达均显著下调(P<0.05或P<0.01),OB和颅骨骨形成能力、松质骨和皮质骨BM D及股骨形态大小均显著下降(P<0.05或P<0.01)。与TC组相比,TS组TGF-β和Osx mRNA及p-Smad2/3蛋白表达均显著上调(P<0.05或P<0.01),OB和颅骨骨形成能力显著增强,股骨湿重(P<0.01)显著增加;TD组TGF-β、Smad2、Runx2和Osx mRNA及p-Smad2/3和Smad4蛋白表达显著上调(P<0.05或P<0.01),OB和颅骨骨形成能力显著增强,松质骨BM D、股骨湿重、股骨远端冠状轴和股骨远端矢状轴宽度显著升高(P<0.01);与TS组相比,TD组Smad2和Osx mRNA及p-Smad2/3和Smad4蛋白表达上调(P<0.05),OB和颅骨骨形成能力增强,股骨远端矢状轴宽度(P<0.05)显著增加。结论:下坡跑对T2DM小鼠骨产生的直接作用力通过激活TGF-β/Smad途径促进骨形成,增加BMD,改善骨湿重和形态大小,且其效果优于游泳产生的间接作用力。

Objective： to explore the effect of different mechanical stimulation on TGF-β/Smad pathway and bone formation in type 2 diabetes mellitic mice. Method： T2 DMmice,built by high-fat diet and injection STZ,were randomly divided into T2 DMcontrol group（ T2 DM）,T2 DMswimming group（ TS） and T2 DMdownhill group（ TD）,and also normal control group.The mice of TS and TD group were respectively treated with 8 weeks of swimming and downhill running.RT-PCR was used to detect the mRNA expression of related factors in the right femur. Western-blotting was used to detect the expression of related factor proteins in the right tibia. BMSCs were cultured and induced to differentiate into OB. Alizarin Red staining was used to stain OB.The skull was stained with Alizarin Red dye.Left femur BMD was detected by Micro-CT. The wet weight and bone shape of right femur were detected by electronic scale and vernier caliper. Results： Compared with ZC group,the mRNA expression of TGF-β,Smad2,Smad3,Smad4,Runx2 and Osx and the protein expression of p-Smad2,p-Smad3 and Smad4 in TC group were significantly decreased（ P〈0.05 or P〈0.01）. The bone formation capacity of OB and skull,bone mineral density of trabecular and cortical and also the morphological size of femur were significantly decreased. Compared with TC group,the mRNA expression of TGF-β,Osx and the protein expression of p-Smad2 and p-Smad3 were significantly up-regulated in TS group（ P〈0.05 or P〈0. 01）. The osteoblastic ability of OB and skull was significantly increased（ P〈0. 05 or P〈0. 01）; the wet weight of femur was improved（ P〈0.01）. The mRNA expression of TGF-β,Smad2, Runx2 and Osx and protein expression of p-Smad2,p-Smad3 and Smad4 were significantly up-regulated in TD group（ P0.05 or P0.01）.The osteoblastic capacity of OB and skull,BMD of trabecular,wet weight of the femur,the width of the distal coronal axis of the femur and the sagittal axis of the distal femur were significantly increased（ P〈0. 01）. Compared with TS group,the mRNA expression of Smad2 and Osx and protein expression of p-Smad2,p-Smad3 and Smad4 of TD group were improved（ P〈0.05）.The osteoblastic ability of OB and skull was enhanced and the width of sagittal axis of femur was significantly increased（ P〈0.05）. Conclusion： Bone formation in T2 DMmice was inhibited.The direct effect of downhill running on bone formation in T2 DMmice was improved by activating TGF-β/Smad pathway,promoting bone formation,increasing BMD,and improving bone wet weight and shape,and its effect was superior to the indirect force generated by swimming.