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目的探讨糖尿病心肌病(DCM)中转化生长因子β_1(TGFβ_1)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,TGFβ_1、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 TGFβ_1、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),TGFβ_1、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TGFβ_1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。
Objective To investigate the activation of Smad signaling pathway associated with transforming growth factor β 1 (TGFβ_1) in diabetic cardiomyopathy (DCM) and the intervention of valsartan. Methods Forty male Wistar rats were randomly divided into three groups: control group (n = 8), DCM group (n = 16) and valsartan group (n = 16). High fat and high calorie diet plus low dose streptozotocin DCM rat model was made by injection of streptozotocin (STZ). The valsartan group was treated with valsartan (30 mg / kg) after modeling. The changes of biochemical indexes were observed at the end of the experiment. The changes of cardiac function were observed by hemodynamics. The changes of cardiac function were observed by electron microscopy, Masson staining, The changes of collagen content, TGFβⅡR, Smad2, Smad3 and Smad7 mRNA and protein expression in left ventricular myocardium of rats in each group were detected by real-time quantitative RT-PCR and Western blotting. Results The cardiac function in DCM group was significantly lower than that in control group (P <0.01). The content of collagen in left ventricular myocardium in DCM group was significantly higher than that in control group (17% ± 3% vs 11% ± 3%, P <0.01) Fibrosis, meanwhile TGFβⅡR, Smad2 and Smad3 mRNA expression levels were higher than the control group (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), and the ratios of Smad2 / Smad7 and Smad3 / Smad7 mRNA were also significantly higher than those of the control group (P <0.05). The protein expressions of TGFβ_1, phospho-Pmad-Smad3 and P-Smad3 were significantly increased The ratios of P-Smad2 / Smad7 and P-Smad3 / Smad7 protein were significantly higher in the control group (103 ± 18 vs 143 ± 17, 107 ± 21 vs 212 ± 43, 89 ± 17 vs 151 ± 32, P <0.01) P <0.05). After intervention with valsartan, the cardiac function of rats improved significantly, and the deposition of myocardial interstitial collagen reduced. At the same time, the molecular abnormalities were significantly improved. The imbalance between Smad2, Smad3 and Smad7 was relieved (P <0.05) ). Conclusion The activation of TGFβ_1-related Smads signaling pathway and the change of the balance between related molecules may be one of the mechanisms of DCM myocardial interstitial fibrosis. Valsartan can reverse this signaling pathway to a certain extent, and can reverse the changes of DCM myocardium The occurrence and development of interstitial fibrosis.