解耦联蛋白2在大鼠高血压心肌重构中的作用

Role of uncoupling protein 2 in hypertensive myocardial remodeling rats

目的采用动物实验,研究解耦联蛋白2(Ucp2)在高血压心肌重构中的作用。方法随机将40只SD大鼠分为假转染假手术组(Sham组)、假转染胸主动脉缩窄(AB)术致心肌肥厚模型组(模型组)、单纯腺相关病毒转染AB术致心肌肥厚组(AAV组)、Ucp2过表达组(Ucp2组)4组。利用超声设备检测大鼠心脏功能,利用天狼猩红(PSR)染色检测大鼠心肌组织胶原含量,实时荧光定量逆转录聚合酶链式反应(qRT-PCR)检测大鼠心肌组织内心肌转化生长因子β(TGF-β)、Ⅰ型胶原蛋白(CollagenⅠ)、肌球蛋白重链β(β-MHC)和脑利尿钠肽(BNP)表达水平,Western-blot法检测蛋白激酶B(AKT)信号通路相关蛋白的表达水平。结果与Sham组比较,模型组、AAV及Ucp2组大鼠心脏超声检查参数左心室舒张末期内径(LVEDD)[(4.98±0.63)、(4.99±0.59)、(4.40±0.56)比(3.01±0.46)mm,F=8.492,P<0.05]、室间隔厚度[(2.51±0.47)、(2.49±0.51)、(2.16±0.48)比(1.83±0.32)mm,F=5.074,P<0.05]及左心室后壁厚度[(2.59±0.54)、(2.53±0.41)、(2.11±0.39)比(1.91±0.41)mm,F=6.834,P<0.05]增加,左心室射血分数(LVEF)[(78.44±6.65)%比(52.16±7.15)%、(53.41±6.68)%、(67.69±6.57)%,F=34.208,P<0.05]及左心室短轴缩短率(FS)[(26.63±3.39)%、(27.03±4.02)%、(35.41±5.02)%比(43.41±5.54)%,F=30.377,P<0.05]降低,其中Ucp2组LVEDD低于模型组及AAV组,LVEF及FS水平高于模型组及AAV组(F=5.508、4.820,P<0.05;F=4.584、4.120,P<0.05)。PSR染色结果显示,模型组及AAV组胶原含量多于Ucp2组(均P<0.05)。qRT-PCR实验显示,AAV组与模型组的TGF-β、CollagenⅠa以及β-MHC、BNP mRNA表达水平高于Ucp2组(均P<0.05)。Western-blot法实验显示,AAV组与模型组p-AKT、糖原合成酶激酶3β(p-GSK3β)、哺乳动物雷帕霉素靶蛋白(mTOR)、核糖体蛋白S6激酶(p70)蛋白表达水平高于Ucp2组(均P<0.05)。结论过表达Ucp2可能通过抑制AKT信号通路,减轻心肌纤维化与心肌肥厚,抑制高血压心肌重构。

Objective To investigate the role of uncoupling protein 2(Ucp2)in hypertensive myocardial remodeling using animal experiments.Methods Forty SD rats were randamly divided into sham-transfected sham-operated group(Sham group),sham-transfected thoracic aorta narrowing(AB)caused myocardial hypertrophy model group(model group),adeno-associated virus-only transfected AB caused myocardial hypertrophy group(AAV group),and Ucp2 overexpression group(Ucp2 group).The cardiac function of rats was detected by echocardiography,the gliadinogen content of rat myocardial tissue was detected using picric sirius red(PSR)staining,the expression levels of myocardial TGF-β,CollagenⅠ,β-MHC and BNP in rat myocardial tissue were detected by real-time fluorescence quantitative reverse transcription polymerase chain reaction(qRT-PCR),and the Western-blot method was used to detect protein kinase B(AKT)signaling pathway-related protein expression.Results Compared with the Sham group in model group,AVV group and Ucp2 group,the echocardiographic parameters left ventricular end-diastolic internal diameter(LVEDD)[(4.98±0.63),(4.99±0.59),(4.40±0.56)vs(3.01±0.46)mm,F=8.492,P0.05],interventricular septal thickness[(2.51±0.47),(2.49±0.51),(2.16±0.48)vs(1.83±0.32)mm,F=5.074,P0.05]and posterior wall thickness[(2.59±0.54),(2.53±0.41),(2.11±0.39)vs(1.91±0.41)mm,F=6.834,P0.05]increased,while left ventricular ejection fraction(LVEF)[(78.44±6.65)%vs(52.16±7.15)%,(53.41±6.68)%,(67.69±6.57)%,F=34.208,P0.05]and left ventricular short axis[(26.63±3.39)%,(27.03±4.02)%,(35.41±5.02)%vs(43.41±5.54)%,F=30.377,P0.05]reduced.The LVEDD in the Ucp2 group was lower than that in the model and AAV groups,and the LVEF and FS levels were higher than those in the model and AAV groups(F=5.508,4.820,P0.05;F=4.584,4.120,P0.05).PSR staining showed that the gliadinogen content was significantly heigher in both the model and AAV groups than in the Ucp2 group(both P0.05).The qPCR experiments showed that the expression levels of TGF-β,CollagenⅠa,andβ-MHC,BNP mRNA were higher in the AAV and model groups than in the Ucp2 group(all P0.05).Western-blot experiments showed that the expression levels of phospho-protein kinases B(p-AKT),glycogen synthase kinase-3 beta(p-GSK3β),mammalian target of rapamycin(mTOR),ribosomaiprotein S6 kinase(S6K/p70)protein were higher in the AAV and model groups than in the Ucp2 group(all P0.05).Conclusion Overexpression of Ucp2 may attenuate myocardial fibrosis and myocardial hypertrophy and inhibit hypertensive myocardial remodeling by inhibiting the AKT signaling pathway.