miR-125b对大鼠心肌梗死后心室重构的调控作用

Regulatory effect of miR-125b on ventricular remodeling after myocardial infarction in rats

目的:探讨微小RNA-125b (miR-125b)通过磷脂酰肌醇3激酶/蛋白激酶B (PI3K/Akt)信号通路对大鼠心肌梗死后心室重构的影响,阐明其作用机制。方法:75只大鼠随机分为假手术组、心肌梗死组和miR-125b抑制物组,每组25只。心肌梗死组和miR-125b抑制物组大鼠建立急性心肌梗死模型,miR-125b抑制物组大鼠经尾静脉注射miR-125b抑制物。4周后处死大鼠,称大鼠体质量,取心脏,剪去大血管和左右心耳,冲洗干净,电子天平秤称心脏质量,计算心脏质量/体质量(HW/BW)、(左心室+室间隔)质量/体质量[(LV+S)/BW]和(左心室+室间隔)质量/心脏质量[(LV+S)/HW],HE染色观察大鼠心肌组织形态表现,Masson染色观察大鼠心肌组织纤维化情况并计算心肌胶原容积积分,免疫荧光染色观察大鼠心肌组织Ⅰ型胶原和Ⅲ型胶原蛋白表达水平,Western blotting法测定大鼠心肌梗死周边区心钠肽(ANP)、脑钠肽(BNP)、PI3K、Akt和磷酸化Akt (p-Akt)蛋白表达水平。结果:HE染色,假手术组大鼠心肌细胞排列整齐;心肌梗死组大鼠心肌肥大,排列紊乱;miR-125b抑制物组大鼠心肌细胞排列较为整齐。与假手术组比较,心肌梗死组和miR-125b抑制物组大鼠HW/BW、(LV+S)/BW和(LV+S)/HW明显升高(P<0.05),胶原容积积分升高(P<0.05),Ⅰ型胶原和Ⅲ型胶原蛋白表达水平升高(P<0.05),ANP和BNP蛋白表达水平升高(P<0.05),PI3K和p-Akt蛋白表达水平降低(P<0.05);与心肌梗死组比较,miR-125b抑制物组大鼠HW/BW、(LV+S)/BW和(LV+S)/HW降低(P<0.05),胶原容积积分降低(P<0.05),Ⅰ型胶原和Ⅲ型胶原蛋白表达水平降低(P<0.05),ANP和BNP蛋白表达水平降低(P<0.05),PI3K和p-Akt蛋白表达水平升高(P<0.05)。结论:抑制miR-125b可通过抑制PI3K/Akt信号通路进而抑制大鼠心肌梗死后心室重构,在逆转心肌梗死后心室重构中发挥重要作用。

Objective:To investigate the effect of miR-125 bon the ventricular remodeling after myocardial infarction in the rats via phosphatidylinositol 3-kinase/protein kinase B(PI3K/Akt)signaling pathway,and to elucidate its mechanism.Methods:A total of 75 rats were divided into sham operation group,myocardial infarction group and miR-125 binhibitor group,with 25 rats in each group.The acute myocardial infarction models were established in the rats in myocardial infarction group and miR-125 binhibitor group.The rats in miR-125 binhibitor group was injected with miR-125 binhibitor via the tail vein.The rats were sacrificed 4 weeks later,the body weights were recorded;the hearts were obtained,and the big vessel and left and right auricular appendix were cut out;the heart weights were weighed.The heart weight/body weight(HW/BW),(left ventricle + ventricular septum)weight/body weight(LV + S)/BW,(left ventricular+ventricular septum)weight/heart weight(LV+S)/HW were calculated.HE staining was used to observe the morphological changes of myocardium tissue.Masson staining was used to observe the myocardial fibrosis,and the collagen volume integral of myocardium was calculated.Immunofluorescence staining was used to observe the expression levels of typeⅠ collagen and typeⅢcollagen proteins in the myocardium tissue of the rats.Western blotting method was used to detect the expression levels of atrial natriuretic peptide(ANP),brain natriuretic peptide(BNP),PI3 K,Akt and phosphorylated Akt(p-Akt)in the peripheral region of myocardial infarction of the rats.Results:The HE staining results showed that the myocarclial cells in sham operation group were arranged neatly;the myocardial cells in myocardial infaction group had hypertrophy and disordered arrangement;the myocardial cells in miR-125 binhibitor group were arranged neatly.Compared with sham operation group,the HW/BW,(LV+S)/BW and(LV+S)/HW of the rats in myocardial infarction group were elevated(P<0.05),the collagen volume integral was increased(P<0.05),the protein expression levels of typeⅠcollagen and typeⅢcollagen were increased(P<0.05),the expression levels ANP and BNP proteins were increased(P<0.05),and the expression levels of PI3K and p-Akt proteins were decreased(P<0.05).Compared with myocardial infarction group,the HW/BW,(LV+S)/BW and(LV+S)/HW of the rats in miR-125 binhibitor group were decreased(P<0.05),the collagen volume integral was decreased(P<0.05),the expression levels of typeⅠcollagen and typeⅢ collagen proteins were decreased(P<0.05),the expression levels of ANP and BNP proteins were decreased(P<0.05),and the expression levels of PI3K and p-Akt proteins were increased(P<0.05).Conclusion:Inhibition of miR-125 bcan inhibit ventricular remodeling after myocardial infarction in the rats by inhibiting the PI3K/Akt signaling pathway,and plays an important role in reversing ventricular remodeling after myocardial infarction。