Objective: To investigate the effects and possible mechanisms of ursodeoxycholic acid (UDCA) on myocardial fibrosis in mice. Method: To observe the expression of transforming growth factor(TGF) -β1, CTGF, MMPs and the degree of myocardial fibrosis, 61 male Kunming mice were randomly divided into normal group, low dose UDCA group, high dose of UDCA group, spironolactone group, and the control group.Isoproterenol (ISO) injection was given subcutaneously (30 d) to make the model of myocardial fibrosis.Corresponding anti-fibrosis drugs (UDCA or spironolactone) were given by gavage.HE staining and Masson staining were performed to explore the inflammation and fibrosis in the myocardium.The expression of collagen Ⅰ and collagen Ⅲ protein was detected by immunohistochemistry to evaluate the degree of fibrosis among the groups.Western blot was used to detect the expression of transforming growth factor, (TGF)-β1, connective tissue growth factor (CTGF), matrix metalloproteinase (MMP)-2, -9, tissue inhibitor of metalloproteinase (TIMP)-4, -1 and anti-phospho-NFKBIA (p-IκB-α) inhibitor of NF-κB (IκB) protein in myocardium. Results: HE and Masson staining results showed that in the normal group, myocardial fibrosis is less, while the control group showed a large amount of fibrotic tissue (P<0.05). Tissue fibrosis in the low/high dose UDCA group and spironolactone group was significantly reduced compared with the control group (P<0.05), in which high dose of UDCA reduces fibrosis more significantly.Immunohistochemistry results showed that collagen Ⅰ and collagen Ⅲ protein expression was significantly increased (P<0.05). Whereas in the low/high UDCA dose group and spironolactone group, collagen Ⅰ and collagen Ⅲ expression were significantly decreased (P<0.05), the high UDCA dose group decreased more significantly.Western blot results suggest that TGFβ-1 expression in the myocardial tissue was significantly increased compared to the normal group (P<0.05), whereas low/high UDCA dose group and spironolactone group, TGFβ-1 protein expression were significantly decreased [UDCA(1.52±0.16), (1.02±0.12), (1.01±0.21)vs (2.73±0.12), P<0.05], in which high UDCA dose group TGFβ-1 protein expression level decreased more significantly.However, there was no significant difference in the expression of CTGF, MMP2/9 and TIMP1/4 protein among the groups (P>0.05). UDCA decrease p-IκB-α expression and increase IκB protein expression dose-dependently. Conclusions: UDCA can relieve isoproterenol induced myocardial fibrosis and reduce the myocardial collagen Ⅰ and collagen Ⅲ deposition in a dose dependent manner.Down-regulating of TGFβ-1 protein expression through the inhibition of TGR5-NF-κB signal transduction pathway might be a potential mechanism underlying UDCA's effects.
目的： 探讨熊去氧胆酸(UDCA)对异丙肾上腺素(ISO)诱导的小鼠心肌纤维化的作用及潜在机制。 方法： 61只雄性昆明小鼠数字表法随机分为正常组、UDCA低剂量组、UDCA高剂量组、螺内酯组和对照组。ISO皮下注射30 d构建心肌纤维化模型。HE、Masson染色检测心肌炎症及纤维化程度；免疫组化检测心肌胶原蛋白(Col)Ⅰ、Ⅲ的表达；蛋白印迹法检测转化生长因子－β1(TGF－β1)、结缔组织生长因子(CTGF)、基质金属蛋白酶2(MMP 2)、基质金属蛋白酶9(MMP 9)、基质金属蛋白酶抑制剂1(TIMP 1)、基质金属蛋白酶抑制剂4(TIMP 4)及NF－κB抑制蛋白(IκB)及其磷酸化形式(p－IκB－α)的表达。 结果： ISO诱导小鼠发生心肌纤维化，Col Ⅰ和Col Ⅲ表达显著增加(P<0.05)；与对照组相比，UDCA组及螺内酯组纤维化程度均显著减轻(P<0.05)，其中UDCA高剂量组纤维化减轻更明显(P<0.05)；UDCA组及螺内酯组ColⅠ、Col Ⅲ及TGF－β1的表达减少[UDCA低剂量组(1.52±0.16)、高剂量组(1.02±0.12)、螺内酯组(1.01±0.21)比对照组(2.73±0.12)，P<0.05]；各组间CTGF、MMP2/9及TIMP1/4的表达差异无统计学意义(P>0.05)。UDCA剂量依赖性地降低p－IκB－α，增加IκB的表达。 结论： UDCA激活受体TGR5，通过下调NF－κB介导的TGF－β1表达发挥抗小鼠心肌纤维化作用。.
Keywords: Collagen; Isopreterenol; Myocardial diseases; Ursodeoxycholic acid.