紫檀芪灌胃对大鼠心肌肥厚的改善作用及其分子机制

Effect of intragastric administration of pterostilbene on myocardial hypertrophy rats and its molecular mechanism

目的观察紫檀芪(PTE)灌胃对大鼠心肌肥厚的改善作用并探讨其分子机制。方法将40只SD大鼠随机分为假手术组、模型组、PTE组、PTE+3-TYP组各10只,除假手术组外均采用腹主动脉缩窄术建立大鼠心肌肥厚模型。PTE组及PTE+3-TYP组大鼠术后均给予PTE灌胃处理,PTE+3-TYP组大鼠在给予PTE的同时经腹腔注射SIRT3特异性阻断剂3-TYP,假手术组及模型组大鼠给予相同体积生理盐水灌胃。8周后对大鼠进行心功能检查,包括左心室舒张末期压力(LVEDP)、左心室收缩末期压力(LVESP)、等容收缩期左心室内压力上升的最大速率(+dp/dt)和等容舒张期左心室压力下降的最大速率(-dp/dt)及血清B型利钠肽(BNP)水平。检测大鼠心肌肥厚指标,包括心体比(HM/BM)、心胫比(HM/TL)及心肌细胞横截面积。超氧化物阴离子荧光探针染色法检测心肌组活性氧(ROS)生成量,Western blotting法检测心肌组织中去乙酰化修饰酶SIRT3、FOXO3a去乙酰化后产物Ac-FOXO3a、抗氧化蛋白NOX2及氧化应激标志蛋白gp91^(phox)的蛋白表达情况。结果各组大鼠心功能指标LVEDP、LVESP、血清BNP水平比较,模型组、PTE+3-TYP组>PTE组>假手术组;+dp/dt、-dp/dt比较,模型组、PTE+3-TYP组<PTE组<假手术组(P均<0.05);模型组与PTE+3-TYP组各心功能指标比较差异均无统计学意义。各组大鼠心肌肥厚指标(HM/TL、HM/BM、心肌细胞横截面积)及心肌ROS生成量比较,模型组、PTE+3-TYP组>PTE组>假手术组(P均<0.05),模型组与PTE+3-TYP组各指标比较差异均无统计学意义。各组大鼠心肌组织SIRT3、NOX2蛋白表达比较,模型组、PTE+3-TYP组<PTE组<假手术组;Ac-FOXO3a、gp91^(phox)蛋白表达比较,模型组、PTE+3-TYP组>PTE组>假手术组(P均<0.05),模型组与PTE+3-TYP组各蛋白表达比较差异均无统计学意义。结论PET可以通过减轻心肌组织氧化应激损伤改善大鼠腹主动脉缩窄所致的心肌肥厚,这种作用可能是通过激活SIRT3/FOXO3a信号通路实现的。

Objective To observe the effect of intragastric administration of pterostilbene(PTE)on myocardial hypertrophy induced by abdominal aortic constriction(AAC)in rats and to explore its molecular mechanism.Methods Forty SD rats were randomly divided into the following four groups:sham group,AAC group,PTE group,and PTE+3-TYP group,with 10 in each.The model of cardiac hypertrophy was established by abdominal aorta constriction in all groups except the sham group.PTE(100 mg/kg/d)was administered intragastrically following AAC surgery in the PTE group and PTE+3-TYP group.SIRT3-specific inhibitor 3-TYP(50 mg/kg/d)was administered intraperitoneally after PTE administration in the PTE+3-TYP group.The rats in the sham group and the AAC group were given the same volume of normal saline.After 8 weeks,cardiac function parameters including left ventricular end-diastolic pressure(LVEDP),left ventricular end-systolic pressure(LVESP)and the maximum rising rate of left ventricular pressure(+dp/dt)and the maximum falling rate of left ventricular pressure(-dp/dt)in the isovolumetric contraction phase were detected by hemodynamics;cardiac index[heart mass/body mass(HM/BM)and heart mass/tibia length(HM/TL)]was measured,serum brain natriuretic peptide(BNP)level was detected by ELISA,and cardiomyocyte cross-sectional area was detected by wheat embryo agglutinin(WGA)staining.Reactive oxygen species(ROS)production was detected by superoxide anion fluorescence probe(DHE)staining,and the expression levels of SIRT3,Ac-FoxO3A,NOX2 and gp91^(phox) in the myocardia were detected by Western blotting.Results The cardiac function parameters of LVEDP and LVESP and the BNP level were the highest in the AAC group and PTE+3-TYP group,and were the lowest in the sham group(all P<0.05).The±dp/dt was the highest in the sham group,and the lowest in the AAC group and PTE+3-TYP group(all P<0.05).There was no significant difference in cardiac function indexes between the AAC group and the PTE+3-TYP group.Comparison of cardiac indexes(HM/TL,HM/BM),myocardial hypertrophy indexes(myocardial cell cross-sectional area,serum BNP level)and myocardial ROS production among all groups showed that AAC group,PTE+3-TYP group>PTE group>sham group(P<0.05).There was no statistically significant difference in these indicators between the AAC group and PTE+3-TYP group.Comparison of the protein expressions of SIRT3 and NOX2 in myocardial tissue showed that AAC group,PTE+3-TYP group<PTE group<sham group(all P<0.05).The protein expression levels of Ac-FOXO3a and gp91^(phox) were in the following order:AAC group,PTE+3-TYP group>PTE group>sham group(all P<0.05).There was no statistically significant difference in the protein expression levels between the AAC group and PTE+3-TYP group.Conclusion PTE alleviates oxidative stress injury of myocardial tissues in rats by activating the SIRT3/FOXO3a pathway,which plays a protective role against myocardial hypertrophy induced by abdominal aortic coarctation.