N-乙酰半胱氨酸对急性心肌梗死小鼠心功能的影响

Influence of N-Acetylcysteine on heart function of acute myocardial infarction mice

目的观察N-乙酰半胱氨酸(N-acetylcysteine,NAC)处理的急性心肌梗死(acute myocardial infarction,AMI)小鼠心功能及心肌组织肿瘤坏死因子受体相关因子6(tumor necrosis factor receptor-associated factor-6,TRAF6)、核因子-κB(nuclear factor-κB,NF-κB)P65蛋白表达变化,探讨NAC对急性心肌梗死小鼠心功能的影响及可能机制。方法雄性C57 BL/J6小鼠30只,随机分为AMI组、AMI+NAC组、假手术组各10只。AMI组、AMI+NAC组小鼠结扎左冠状动脉前降支制备AMI模型;假手术组只开胸,不结扎。造模成功后,AMI+NAC组小鼠腹腔注射NAC 100 mg/(kg·d),连续7 d;AMI组、假手术组小鼠腹腔注射等量生理盐水。7 d后,3组小鼠行超声心动图检查,测量左室射血分数、左心室舒张末期内径、左心室收缩末期内径;采集3组小鼠后腹主动脉血,采用ELISA法检测血清肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、白细胞介素(interleukin,IL)-6和IL-1β水平之后处死小鼠取心脏,HE染色观察心肌组织病理学变化,采用实时荧光定量PCR法检测TRAF6、NF-κB P65 mRNA相对表达量,采用免疫组织化学法检测TRAF6、NF-κB P65蛋白表达。结果造模7 d后,AMI组左室射血分数[(43.33±2.31)%]小于AMI+NAC组[(68.33±4.16)%]、假手术组[(81.67±3.06)%](P<0.05),左心室舒张末期内径[(4.35±0.11)mm]、左心室收缩末期内径[(4.70±0.14)mm]均大于AMI+NAC组[(4.00±0.05)、(3.98±0.16)mm]、假手术组[(3.85±0.09)、(2.04±0.09)mm](P<0.05),AMI+NAC组左室射血分数小于假手术组,左心室舒张未期内径、左心室收缩未期内径均大于假手术组(P<0.05)。假手术组小鼠心肌组织结构正常,AMI组小鼠心肌组织结构紊乱,NAC+NAC组小鼠心肌细胞紊乱程度较AMI组减轻。AMI组心肌TRAF6、NF-κB P65 mRNA相对表达量(3.22±0.23、3.82±0.16)及TRAF6、NF-κB P65蛋白平均光密度值(0.075±0.006、0.071±0.002)均高于AMI+NAC组(2.11±0.25、2.14±0.14、0.056±0.007、0.047±0.004)、假手术组(1.00±0.06、1.00±0.05、0.053±0.005、0.039±0.005)(P<0.05),AMI+NAC组均高于假手术组(P<0.05)。AMI组血清IL-6[(277.30±31.42)ng/L]、IL-1β[(105.57±2.16)ng/L]、TNF-α[(105.67±7.09)ng/L]水平均高于AMI+NAC组[(151.16±9.86)、(81.63±6.85)、(75.33±6.03)ng/L]、假手术组[(135.29±10.27)、(50.95±7.22)、(48.33±3.51)ng/L](P<0.05),AMI+NAC组均高于假手术组(P<0.05)。结论NAC可减少AMI小鼠炎性因子释放,改善心功能,其机制可能与NAC抑制TRAF6、NF-κB信号转导通路的激活有关。

Objective To observe the changes of heart function and tumor necrosis factor receptor-associated factor-6(TRAF6)and nuclear factor-κB(NF-κB)P65 proteins in acute myocardial infarction(AMI)mice after being treated with N-acetylcysteine(NAC),and to investigate the influence of NAC on the heart function in AMI mice and its potential mechanism.Methods Thirty male C57BL/J6 mice were randomly divided into AMI group,AMI+NAC group and sham-operation group,with 10 mice in each group.The mice models were prepared by ligating the anterior descending branch of left coronary artery in AMI and AMI+NAC groups,while sham-operation group was only performed thoracotomy without ligating coronary artery.After modeling,AMI+NAC group was intraperitoneally injected with 100mg/(kg·d)NAC for 7days,and AMI and AMI+NAC groups were injected equivalent volume of normal saline.Echocardiography was done to measure left ventricular ejection fraction,left ventricular end-diastolic dimension and left ventricular end-systolic dimension in three groups 7days later.The blood was collected from the posterior abdominal aorta.The levels of tumor necrosis factor-α(TNF-α),interleukin(IL)-6 and IL-1βwere detected by ELISA.All mice were sacrificed to obtain the heart.The histopathological changes were observed by HE staining.The relative expressions of TRAF6 and NF-κB P65 mRNAs were detected by real-time fluorescence quantitative PCR,and the expressions of TRAF6 and NF-κB P65 proteins were detected by immunohistochemisty in three groups.Results By day 7 after modeling,left ventricular ejection fraction was smaller in AMI group[(43.33±2.31)%]than that in AMI+NAC group[(68.33±4.16)%]and sham-operation group[(81.67±3.06)%](P<0.05),and in AMI+NAC group than that in sham-operation group(P<0.05).Left ventricular end-diastolic dimension and left ventricular end-systolic dimension were longer in AMI group[(4.35±0.11),(4.70±0.14)mm]than those in AMI+NAC group[(4.00±0.05),(3.98±0.16)mm]and sham-operation group[(3.85±0.09),(2.04±0.09)mm](P<0.05),and longer in AMI+NAC group than those in sham-operation group(P<0.05).The myocardial structure was normal in sham-operation group,and was disordered in AMI group,which was slighter in AMI+NAC group compared with AMI group.The relative expressions of TRAF6 and NF-κB P65mRNA,and the average optical intensity scores of TRAF6 and NF-κB P65 proteins were higher in AMI group(3.22±0.23,3.82±0.16;0.075±0.006,0.071±0.002)than those in AMI+NAC group(2.11±0.25,2.14±0.14;0.056±0.007,0.047±0.004)and sham-operation group(1.00±0.06,1.00±0.05;0.053±0.005,0.039±0.005)(P<0.05),and higher in AMI+NAC group than those in sham-operation group(P<0.05).The levels of IL-6,IL-1βand TNF-αwere higher in AMI group[(277.30±31.42),(105.57±2.16),(105.67±7.09)ng/L]than those in AMI+NAC group[(151.16±9.86),(81.63±6.85),(75.33±6.03)ng/L]and sham-operation group[(135.29±10.27),(50.95±7.22),(48.33±3.51)ng/L](P<0.05),and higher in AMI+NAC group than those in sham-operation group(P<0.05).Conclusion NAC can reduce the release of inflammatory factors and improve the heart function in AMI mice,probably by inhibiting TRAF6and NF-κB signaling pathway.