蛋白酶激活受体2/P38MAPK信号通路在缺血后处理对抗老年糖尿病大鼠心肌缺血再灌注损伤中的作用

Role of PAR-2/P38MAPK Pathway in Protective Effects of Ischemic Postconditioning against Myocardial Ischemia Reperfusion Injury of Aged Diabetic Rats

目的:研究蛋白酶激活受体2/P38MAPK(PAR-2/P38MAPK)信号通路在缺血后处理(IPost)对抗老年糖尿病大鼠心肌缺血再灌注(I/R)损伤中的作用。方法:22-24月龄雄性Wistar大鼠32只,随机选取24只采用链脲佐菌素(STZ)腹腔注射制备老年糖尿病模型。成模大鼠随机分成3组(每组8只):I/R组、IPost组、PAR-2抑制剂组(PAR-2组),PAR-2组大鼠于缺血处理前1h尾静脉注射PAR-2抑制剂FSLLRY-NH2,其余处理同IPost组;未造模的8只大鼠作为对照组(SC组)。采用黄嘌呤氧化酶法和硫代巴比妥比色法分别测定血清超氧化物歧化酶(SOD)活性及丙二醛(MDA)浓度,TUNEL法检测心肌细胞凋亡率,Western Blotting测定PAR-2及P38MAPK、P-P38MAPK蛋白表达水平。结果:I/R组MDA浓度、心肌细胞凋亡率及P-P38MAPK水平均较SC组显著增加(P<0.05或P<0.01),SOD活性、PAR-2蛋白表达水平明显降低(P<0.01)。IPost组SOD活性及PAR-2水平较I/R组显著增加(P<0.05),P-P38MAPK水平、MDA浓度及心肌细胞凋亡率均下降(P<0.01)。PAR-2抑制剂则可抑制IPost作用,使P-P38MAPK蛋白表达水平上调、心肌细胞凋亡率增加、MDA浓度升高、SOD活性降低(P<0.05或P<0.01)。结论:IPost对老年糖尿病大鼠心肌I/R损伤有保护作用,其机制与PAR-2/P38MAPK信号通路的调节有关。

Objective： To investigate the role of protease-activated receptor 2（PAR-2）/P38MAPK pathway in protective effects of ischemic postconditioning （IPost） against myocardial ischemia reperfusion（I/R） injury of aged diabetic rats. Method： 32 healthy aged（22--24 months） male Wistar rats were obtained. 24 models of aged diabetic rats were induced by using streptozotocin（STZ） and then the diabetic rats were randomly divided into 3 groups （8 animals in each group） ： ischemia/reperfusion group （I/R group）, ischemic postconditioning group （IPost group ） and protease-activated receptor 2 inhibition group（PAR-2 group）. FSLLRY-NH2 was injected to inhibit PAR-2 an hour of ischemic treatment ago in PAR-2 group. The remaining treatment was the same as IPost group. In addition, the remaining 8 rats served as saline control group（SC group）. The activity of superoxide dismutase（SOD） was detected by xanthine oxidase method and the content of malonaldehyde（MDA） was measured by thiobarbituric acid colorimetry in each group. Myocardial apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling（TUNEL）staining. The protein levels of PAR-2, P38MAPK and P-P38MAPK were detected by Western blotting. Resuits： Compared with SC group, MDA contents, myocardial apoptosis rate and P-P38MAPK level increased significantly in I/R group（P〈0. 01）, the activity of SOD and protein level of PAR-2 decreased significantly （P〈0.01）. Compared with I/R group, the activity of SOD and protein level of PAR-2 increased in IPost group（P〈0.05）, the protein level of P-P38MAPK, MDA contents and myocardial apoptosis rate decreased in IPost group（P〈0.01）. However, the protective effect of IPost was inhibited by FSLLRY-NH2. The protein level of P-P38MAPK , MDA contents and myocardial apoptosis rate increased and the activity of SOD decreased significantly （P〈0.05 or P〈0.01）. Conclusion： Ischemic postconditioning has protective effect on myocardial ischemia reperfusion injury of aged diabetic rats. Its mechanism is related to the regulation of PAR-2/P38MAPK pathway.