卡维地洛对异丙肾上腺素诱导的大鼠心肌重构中TGF-β/Smads信号传导通路的作用

The effect of carvedilol on TGF-beta-Smad pathways in myocardial fibrosis(MF) induced by isoproterenol

目的研究TGF-β/Smads信号传导通路在异丙基肾上腺素诱导的心肌重构中的作用及卡维地洛的治疗机制。方法 30只SD大鼠,随机分为3组:20只SD大鼠背部皮下注射异丙基肾上腺素5 mg/(kg·d)10d,建立心肌重构模型。随机分为2组,模型组和卡维地洛组。予卡维地洛组连续灌胃卡维地洛10 mg/(kg·d)4周。4周后测心重指数(CWI);HE、Masson染色观察心肌组织病理变化;半定量RT-PCR法及免疫组化染色检测心肌组织中TGF-β1、Smad3、Smad7 mRNA及蛋白表达情况。结果模型组可见心肌细胞肥大、伸长,肌质变性,核大、深染,Masson染色可见心肌胶原纤维明显增多,治疗组大鼠心肌细胞病理改变较模型组明显减轻;CWI:模型组较对照组CWI升高(P<0.01),治疗组与模型组比较,CWI下降(P<0.01);模型组较对照组TGF-β1及Smad3 mRNA和蛋白的表达均增多(均为P<0.01),Smad7 mRNA和蛋白表达减少(分别为P<0.01和P<0.05);治疗组与模型组比较,TGF-β1及Smad3 mRNA和蛋白表达均降低(P<0.01和P<0.05),Smad7 mRNA和蛋白表达增加(P<0.01和P<0.05)。结论 TGF-β/Smads信号通路参与了异丙肾诱导的心肌重构,阻断该通路可能是卡维地洛抑制心肌重构的机制之一。

Objective To investigate the effect of TGF-beta-Smad signaling pathway in cardiac fibrosis induced by isoproterenol（ISO） in rats and the intervention mechanism of carvedilol. Methods Thirty male Sprague-Dawley rats were randomly divided into ISO model group （M group）, carvedilol treatment group （T group）and control group （C group）. Cardiac fibrosis models were induced in M group and T group by subcutaneous injection of ISO 5 mg/（kg . d）for 10 days. Rats of C group were injected normal saline 5 mL/（kg .d） for 10 days instead, after 10 days, rats of T group were fed carvedilol 10 mg/（ kg. d） for 4 weeks. Rats of M and C group were fed normal saline 10 mL/（ kg. d） for 4 weeks instead, after 4 weeks,all the rats were killed to measure the CWI. The patho- logical changes of myocardial tissue were observed by HE staining and the changes of collagen fiber were detected through Massion staining. The mRNA expression level of TGF-β1, Smad3 and Smad7 hyperplasia were deter-mined by RT-PCR. The protein level of TGF-β1, Smad3 and Smad7 were detected by immunohistochemistry. Re- suits There were changes in M group including cardiac muscle cell hypertrophy, prolongation, fibrosis and calcifi- cation presented between the cells, in addition, myocardial collagen fibers increased significantly in masson dyeing cells in M group than that in T group and C group. T group heart muscle cells showed a parallelism arrange. Be- tween the cells collagen fibers could be found, but the amount and area was decreased markedly. Compared with those of C group, all of the CWI, the expression levers of TGF-β1 mRNA, the Smad3 mRNA, TGF-β1 protein, and the Smad3 protein were significantly increased（ all P 〈0. 01 ） , and the expression levers of Smad7 mRNA and the Smad7 protein were significantly lower in M group （P 〈 0. 01, P 〈 0. 05 ）. However, the expression that in of TGF-β1 mRNA, Smad3 mRNA, TGF-β1 protein and Smad3 protein were much lower（P 〈 0. 01 ,P 〈 0. 05）. The expression of Smad7 mRNA and the Smad7 protein were significantly higher in T group than that in M group （P 〈 0. 01 ,P 〈0. 05）. Conclusions TGF-beta-Smad signaling pathway may play an important role in myocardial fibro- sis induced by ISO, and carvedilol can improve the pathological changes, which might be associated with the inhi- bition of TGF-beta-Smad signaling pathway.