西洋参茎叶总皂苷通过抑制过度内质网应激减轻大鼠心肌缺血／再灌注损伤

Panax quinquefolium saponins protect rat myocardium from ischemia/reperfusion injury through attenuating excessive endoplasmic reticulum stress

目的:观察西洋参茎叶总皂苷(PQS)对大鼠心肌缺血/再灌注(ischemia/reperfusion,I/R)损伤的保护作用,并从内质网应激(ERS)的角度探讨其可能的分子机制。方法:采用SD大鼠心肌I/R模型,随机分为正常对照组、模型组与药物预处理组,检测血流动力学及血清心肌肌钙蛋白T(cTnT)含量,以氯化三苯基四氮唑(TTC)和伊文思蓝双染法检测心梗面积,采用HE染色和TUNEL法分别评估心肌病理损伤和心肌细胞凋亡程度,Western blotting法检测心肌组织凋亡调节因子以及内质网应激相关蛋白的表达。结果:与I/R组相比,PQS+I/R组平均动脉压降低32.0%(P<0.05),左室±dp/dtmax分别升高64.0%和35.0%(P<0.05),血清cTnT含量降低53.3%(P<0.05),坏死面积/缺血面积(AN/AAR)百分比降低65.5%(P<0.05),心肌细胞凋亡率降低54.9%(P<0.05);心肌组织病理损伤程度减轻;抗凋亡蛋白Bcl-2表达升高110.0%(P<0.05),促凋亡蛋白Bax表达降低47.8%(P<0.05),钙网蛋白(CRT)表达降低43.4%(P<0.05),C/EBP同源蛋白(CHOP)和剪切后的caspase-12蛋白表达分别降低38.6%和23.7%(P<0.05)。结论:PQS可显著减轻大鼠心肌I/R损伤,其机制与降低I/R诱导的CRT过表达,抑制CHOP、caspase-12等内质网凋亡通路激活,从而抑制过度ERS介导的细胞凋亡有关。

AIM ： To investigate whether excessive endoplasmic reticulum stress （ERS） is involved in the pro- tective mechanism of Panax quinquefolium saponins （PQS） against ischemia/reperfusion （I/R） injury in rat myocardium. METHODS ： The model of myocardial I/R injury in vivo was made by ligating the left anterior descending artery for 45 min followed by 24 h of reperfusion in SI） rats. The hemodynamics and serum content of cardiac troponin T （cTnT） were meas- ured. The myocardial infarct size was measured by Evans blue and 2, 3, 5-triphenyhetrazolium chloride （TTC） staining. Cardiomyocyte apoptosis was detected using in situ TDT-mediated dUTP nick end labeling （TUNEL）. The protein levels of glucose-regulated protein 78 （ GRP78 ）, calreticulin （ CRT）, C/EBP homologous protein （ CHOP）, caspase-12, apopto- sis-associated proteins Bax and Bcl-2 were determined by Western blotting. RESULTS： Compared with I/R group, the mean arterial pressure in PQR ＋ IR group was decreased by 32.0%, and left ventricular ＋ dp/dt~= was increased by 64. 0% and 35.0%, respectively. The serum content of cTnT was decreased by 53.3%, the percentage of area of necrosis （ AN）/area at risk （AAR） was reduced by 65.5% and the apoptosis rate was decreased by 54.9%. The myocardial patho- logical changes were improved. Bcl-2 protein expression was increased by 110. 0% and that of Bax was decreased by 47. 8%. CRT protein expression was decreased by 43.4 %, CHOP protein expression and the protein level of cleavedcaspase-12 were decreased by 38.6% and 23.7% in PQS ＋ I/R group. CONCLUSION： PQS alleviates I/R injury in my- ocardium by inhibition of excessive ERS.