【摘要】 目的探讨糖尿病心肌病（DCM）中转化生长因子β₁（TGFβ₁）相关的 Smads 信号通路的激活及缬沙坦的干预作用。方法雄性 Wistar 大鼠40只,随机分为3组:对照组（8只）,DCM 组（16只）,缬沙坦组（16只）,采用高脂高热量饲料喂养加小剂量链脲佐菌素（STZ）注射制作 DCM 大鼠模型。成模后缬沙坦组给以缬沙坦（30 mg/kg）干预治疗,实验末观察大鼠生化指标的变化,血流动力学观察大鼠心功能的变化,应用电子显微镜、Masson 染色、实时定量逆转录（RT）-PCR 和 Western印迹技术,检测各组大鼠左室心肌组织胶原含量,TGFβ₁、TGFβⅡR、Smad2、Smad3及 Smad7 mRNA 和蛋白质表达水平的变化。结果 DCM 组大鼠心功能明显低于对照组（P<0.01）,左室心肌组织胶原含量明显高于对照组（17%±3% vs 11%±3%,P<0.01）,存在心肌间质纤维化;同时 TGFβ₁、TGFβⅡR、Smad2和 Smad3 mRNA 表达水平均高于对照组（0.0054±0.0009 vs 0.0126±0.0057,0.0523±0.0218 vs 0.0877±0.0272,0.0413±0.0186 vs 0.0884±0.0146,0.0064±0.0021 vs 0.012±0.0048,P<0.05～0.01）,Smad2/Smad7和 Smad3/Smad7的 mRNA 的比值也明显高于对照组（P<0.05）,TGFβ₁、磷酸化（P）-Smad2和 P-Smad3蛋白质表达水平明显高于对照组（103±18 vs 143±17,107±21vs 212±43,89±17 vs 151±32,P<0.01）,P-Smad2/Smad7和 P-Smad3/Smad7蛋白质的比值也明显升高（P<0.05）。应用缬沙坦干预治疗后,大鼠心功能明显好转,心肌间质胶原沉积减轻,同时上述分子异常均明显好转,Smad2、Smad3和 Smad7之间的失平衡现象较 DCM 组减轻（均 P<0.05）。结论TGFβ₁相关的 Smads 信号通路的激活及相关分子之间的平衡状态的改变可能是 DCM 心肌间质纤维化的机制之一,缬沙坦通过抑制这一信号途径,在一定程度上可逆转 DCM 心肌间质纤维化的发生和发展。更多还原

【Abstract】 Objective To study the activation of transforming growth factor（TGF）-β₁/Smads signal pathway in diabetic cardiomyopathy（DCM）and effects of valsartan thereon.Methods 40 male Wistar rats were randomly divided into 3 groups:DCM group（n=16,fed with high-calorie fat diet for 4 weeks,injected intraperitoneally with streptozocin so as to establish DCM model,and then perfused into the stomach with normal saline once daily since the injection of STZ for 16 weeks）,valsartan group（n=16, perfused into the stomach with valsartan at the dose of 30 mg/kg once a day for 16 weeks after the establishment of DCM model）,and control group（n=8,fed with normal diet and perfused into the stomach with normal saline once daily for 16 weeks）.At the end of the experiment,the contents of fast blood-glucose （FBG）,fast insulin（FIN）,serum cholesterol,and triglyceride were detected,and insulin sensitivity index （ISI）was calculated.Cardiac catheterization was performed to measure the hemodynamics indexes:left ventricular systolic pressure（LVSP）,left ventricular end diastolic pressure（LVEDP）,and maximal rise/ fall velocity of ventricular pressure(±dp/dt_max),and the left ventricular diastolic function（T）was calculated.Pieces of myocardium tissue were taken out to undergo ultrastructural histopathological examination by transmission electron microscopy.The content of collagen was quantified by Masson three- color staining.Real-time RT-PCR and Western-blotting were used to detect the mRNA expression and protein expression of TGFβ₁,TGFβRⅡ,Smad2,Smad3,and Smad7.Results By the end of experiment the levels of FBG,triglyceride,and cholesterol increased and the ISI decreased significantly in the DCM and valsartan groups（all P<0.01）.Compared with the valsartan and control groups the levels of LVEDP and T significantly increased,and the levels of LVSP and±dp/dt_max,significantly degreased（all P<0.01）;and the LVEDP of the valsartan group was significantly higher than that of the control group and the±dp/dt_max of the valsartan group was significantly lower than that of the control group（P<0.01）.The volume of collagen in the myocardial tissue of the DCM group was 17%±3%,significantly higher than that of the control group （11%±3%,P<0.01）.The content of collagen in the myocardial tissue of the valsartan group was lower significantly than that of the DCM group.The levels of mRNA expression of TGFβ₁,TGFβRⅡ,Smad2, and Smad3 were 0.0126±0.0057,0.0877±0.0272,0.0884±0.0146,and 0.012±0.0048 respectively, all significantly higher than those of the control group（0.0054±0.0009,0.0523±0.0218,0.0413± 0.0186,and 0.0064±0.0021 respectively,all P<0.05～0.01）.The ratios Smad2/Smad7 and Smad3/ Smad7 of the DCM group were significantly higher than those of the control group（both P<0.05）.The protein levels of TGFβ₁,P-Smad2,and P-Smad3 were 143±17,212±43,and 151±32 respectively,all significantly higher than those of the control group（103±18,107±21,and 89±17 respectively,P< 0.01）,The P-Smad2/Smad7 and P-Smad3/Smad7 of the DCM group were significantly higher than those of the control group（both P<0.05）,The Smad2/Smad7（or P-Smad2/Smads7）and Smad3/Smad7（or P- Smad3/Smads7）of the valsartan group was significantly lower than those of the DCM group（both P< 0.05）.Conclusion Activation of TGFβ₁/Smads signal pathway and imbalance between Smad2,3 and Sma7 may be one of the mechanisms of myocardial interstitial fibrosis in DCM.Valsartan can prevent myocardium from damage by blocking the signal pathway.更多还原