重组人脑利钠肽对心肌缺血再灌注损伤大鼠心肌自噬的影响

Effects of recombinant human brain natriuretic peptide on myocardial autophagy in myocardial ischemia-reperfusion injury rats

目的 研究重组人脑利钠肽(rhBNP)对心肌缺血再灌注损伤(MIRI)大鼠心肌自噬和Toll样受体-4(TLR4)/核因子κB(NF-κB)信号通路的影响。方法 将SD大鼠随机分为对照组、模型组和实验组,每组10只。模型组和实验组大鼠采用冠状动脉前降支结扎法构建MIRI大鼠模型。实验组大鼠在建模前1 d尾静脉注射1.5μg·kg^(-1)rhBNP,模型组和对照组大鼠在相同时间尾静脉注射等量生理盐水。用超声仪检测大鼠心功能指标左心室射血分数(LVEF)和左心室短轴缩短率(LVFS),用2,3,5-氯化三苯基四氮唑(TTC)法检测大鼠心肌梗死面积,用试剂盒检测大鼠血清中白细胞介素-6(IL-6)和肿瘤坏死因子-α(TNF-α)水平,用蛋白质印迹(Western blot)法检测心肌组织中微管相关蛋白1轻链3(LC3)、TLR4和NF-κB蛋白表达水平。结果 对照组、模型组和实验组大鼠LVEF水平分别为(79.95±5.74)%,(47.68±3.17)%,(62.74±4.69)%,LVFS水平分别为(52.30±3.88)%,(31.75±2.01)%,(41.88±3.10)%,心肌梗死面积分别为(1.63±0.44)%,(40.61±3.42)%,(26.19±2.55)%,血清中IL-6水平分别为(26.06±3.75),(71.96±4.27),(46.45±3.35)ng·L^(-1),TNF-α水平分别为(1.35±0.13),(3.43±0.38),(2.41±0.20)ng·L^(-1),心肌组织LC3Ⅱ/Ⅰ水平分别为0.97±0.06,3.88±0.30,1.67±0.20,TLR4蛋白表达水平分别为0.51±0.04,1.24±0.15,0.71±0.06,NF-κB蛋白表达水平分别为0.30±0.02,0.64±0.04,0.48±0.03;模型组、实验组与对照组比较,实验组与模型组比较,上述指标差异均有统计学意义(均P<0.05)。结论 rhBNP可改善MIRI,其作用机制可能与抑制心肌自噬和TLR4/NF-κB信号通路介导的炎症反应有关。

Objective To investigate the effect of recombinant human brain natriuretic peptide(rhBNP) on myocardial autophagy and Toll-like receptors-4(TLR4)/nuclear factor kappa-B(NF-κB) signal pathway in rats with myocardial ischemia-reperfusion injury(MIRI).Methods SD rats were randomly divided into control group,model group and experimental group,with 10 rats in each group.Rats in model group and experimental group were ligated by anterior descending coronary artery to construct MIRI rat model.Rats in experimental group were injected with 1.5% μg·kg^(-1) rhBNP into tail vein on 1 day before modeling,rats in MIRI group and control group were injected with the same amount of normal saline at the same time.The left ventricular ejection fraction( LVEF) and left ventricular short axis shortening( LVFS) were measured by ultrasound,the myocardial infarction area was measured by 2,3,5-triphenyltetrazolium chloride( TTC),the interleukin-6( IL-6) and tumor necrosis factor-α( TNF-α) in serum were detected by kit,microtubule associated protein 1 light chain 3( LC3),TLR4 and NF-κB protein expression levels were detected by Western blot.Results The levels of LVEF in control group,model group and experimental group were( 79.95 ± 5.74) %,( 47.68 ± 3.17) %,( 62.74 ± 4.69) %,respectively;the levels of LVFS were( 52.30 ± 3.88) %,( 31.75 ± 2.01) %,( 41.88 ± 3.10) %,respectively;the area of myocardial infarction were( 1.63 ± 0.44) %,( 40.61 ± 3.42) %,( 26.19 ± 2.55) %,respectively;the levels of IL-6 in serum were( 26.06 ± 3.75),( 71.96 ± 4.27),( 46.45 ± 3.35) ng·L^(-1),TNF-α were( 1.35 ± 0.13),( 3.43 ± 0.38),( 2.41 ± 0.20) ng·L^(-1),respectively;the levels of LC3 Ⅱ/Ⅰwere 0.97 ± 0.06,3.88 ± 0.30,1.67 ± 0.20;the expression levels of TLR4 in myocardial tissue were 0.51 ± 0.04,1.24 ± 0.15,0.71 ± 0.06;the expression levels of NF-κB protein were 0.30 ± 0.02,0.64 ± 0.04,0.48 ± 0.03.There were significant differences of the above indexes in experimental group and model group compared with control group( all P < 0.05).Conclusion rh BNP can improve MIRI,and its mechanism may be related to the inhibition of myocardial autophagy and TLR4/NF-κB signaling pathway mediated inflammatory response.