目的 研究丹参酮II_A改善大鼠急性心肌梗死（acute myocardial infarction，AMI）作用机制。方法 将SD大鼠随机分为假手术组、模型组、丹参酮II_A（5 mL/kg）组、miR-376b-5p mimics＋丹参酮II_A组和miR-376b-5p inhibitor＋丹参酮II_A组，每组10只。除假手术组外，其他各组采用大鼠冠状动脉前降支结扎法建立AMI模型，给予药物干预12周后，qRT-PCR检测大鼠心肌组织中miR-376b-5p基因表达；采用苏木素-伊红（HE）和Masson染色观察心肌组织病理变化和纤维化程度；ELISA检测血清炎症因子水平；免疫组化检测心肌组织中I型胶原蛋白（collagen type I，Col1）、III型胶原蛋白（collagen type III，Col3）和α-平滑肌肌动蛋白（α-smooth muscle actin，α-SMA）表达；Western blotting检测心肌组织中转化生长因子-β1（transforming growth factor-β1，TGF-β1）/Smad和同源基因家族成员A（Ras homolog gene family member A，RhoA）/Rho相关螺旋卷曲蛋白激酶（Rho-associated coiled-coil-containing protein kinase，ROCK）信号通路相关蛋白表达。结果 与假手术组比较，模型组大鼠心肌组织中miR-376b-5p表达和血清中白细胞介素-1β（interleukin-1β，IL-1β）、肿瘤坏死因子-α（tumor necrosis factor-α，TNF-α）水平及磷酸肌酸激酶同工酶（creatine kinase-myocardial band，CK-MB）、乳酸脱氢酶（lactate dehydrogenase，LDH）活性均显著升高（P<0.05）；心肌细胞排列不齐，间隙大，可见明显胶原纤维沉积；心肌组织Col1、Col3、α-SMA、TGF-β1、磷酸化Smad2/3（phosphorylated Smad2/3，p-Smad2/3）、RhoA、ROCK1/2和纤连蛋白（fibronectin，FN）蛋白表达均显著升高（P<0.05），Smad7蛋白表达显著降低（P<0.05）。与模型组比较，丹参酮II_A组和miR-376b-5p抑制剂＋丹参酮II_A组心肌组织细胞形态及纤维化程度得到明显改善，血清中IL-1β、TNF-α水平和CK-MB、LDH活性显著降低（P<0.05），心肌组织Col1、Col3、α-SMA、TGF-β1、p-Smad2/3、RhoA、ROCK1/2和FN蛋白表达显著降低（P<0.05），Smad7蛋白表达显著升高（P<0.05）。结论 丹参酮II_A可能通过抑制心肌组织中miR-376b-5p表达和TGF-β1/Smad、RhoA/ROCK信号通路活化，从而对AMI模型大鼠心室重构起到保护作用。

Objective To study the mechanism of tanshinone II_A in improving acute myocardial infarction (AMI) in rats. Methods SD rats were randomly divided into sham operation group, model group, tanshinone II_A (5 mL/kg) group, miR-376b-5p mimics + tanshinone II_A group and miR-376b-5p inhibitor + tanshinone II_A group, with 10 rats in each group. Except sham operation group, AMI models were established by ligating the anterior descending coronary artery in rats in other groups. After 12 weeks of drug intervention, the expression of miR-376b-5p gene in myocardial tissue of rats was detected by qRT-PCR. HE and Masson staining were used to observe the pathological changes and fibrosis degree of myocardial tissue. Levels of inflammatory factors in serum were detected by ELISA. The expressions of collagen type I (Col1), collagen type III (Col3) and α-smooth muscle actin (α-SMA) in myocardial tissue were detected by immunohistochemistry. Western blotting was used to detect transforming growth factor-β1 (TGF-β1)/Smad and Ras homolog gene family member A (RhoA)/Rho-associated coiled-coil-containing protein kinase (ROCK) signal pathway related protein expressions in myocardial tissue. Results Compared with sham operation group, the expression of miR-376b-5p in myocardial tissue and levels of IL-1β, TNF-α, activities of creatine kinase isoenzyme (CK-MB) and lactate dehydrogenase (LDH) were significantly increased (P < 0.05), myocardial cells were arranged irregularly, with large gaps, and obvious collagen fiber deposition could be seen; The expressions of Col1, Col3, α-SMA, TGF-β1, phosphorylated Smad2/3 (p-Smad2/3), RhoA, ROCK1/2 and fibronectin (FN) in myocardial tissues were significantly increased (P < 0.05), and Smad7 protein expression was significantly decreased (P < 0.05). Compared with model group, tanshinone II_A group and miR-376b-5p inhibitor + tanshinone II_A group significantly improved the cellular morphology and fibrosis degree of myocardial tissue, levels of IL-1β, TNF-α and activities of CK-MB, LDH in serum were significantly decreased (P < 0.05), Col1, Col3, α-SMA, TGF-β1, p-Smad2/3, RhoA, ROCK1/2 and FN protein expressions in myocardial tissues were significantly decreased (P < 0.05), p-Smad7 protein expression was significantly increased (P < 0.05). Conclusion Tanshinone II_A may protect the ventricular remodeling in AMI model rats by inhibiting the expression of miR-376b-5p and the activation of TGF-β1/Smad and RhoA/ROCK signal pathways in myocardial tissue.

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包头医学院科学研究基金资助项目（BYJJ-ZRQM202226）