雌激素对大鼠心肌缺血再灌注过程中iNOS表达及凋亡相关性的实验研究

Effect of E_2 on the relationship of iNOS expression and apoptosis during myocardial ischemia-reperfusion process

[目的]通过比较单纯缺血再灌注及17β-雌二醇(E2)干预后的心肌诱导型一氧化氮合酶(iNOS)、过氧化物歧化酶(SOD)、丙二醛(MDA)及凋亡的表达,分析其变化规律,探讨雌激素的心肌保护机制。[方法]雄性SD大鼠24只,随机分为单纯缺血再灌注组(I/R组)及雌激素干预的缺血再灌注组(E2组)。两组大鼠均结扎冠状动脉左前降支(LAD)20 min后开放结扎恢复血流灌注,制备心肌缺血再灌注模型。利用南京建成生化检测试剂盒分别检测再灌注30、120及200 min心肌iNOS表达、SOD活性及MDA含量变化;利用流式细胞仪检测心肌细胞凋亡变化。[结果]再灌注30、120和200 min,单纯I/R组与E2组iNOS表达分别为:(1050.474±10.310)、(677.639±6.213)、(529.000±3.520)U/mg.prot及(1997.182±6.75)、(1955.830±10.237)、(1754.375±9.813)U/mg.prot。各时间点比较,E2组均显著高于I/R组,P<0.01。再灌注30 min时,E2组心肌SOD活性为(88.721±0.309)U/mL,高于I/R组(61.337±0.130)U/mL,P<0.05;与单纯I/R组(36.648±0.259)μmol/g比较,E2组MDA含量(33.994±0.110)μmol/g明显降低,二者间差异有显著性意义,P<0.05;E2组心肌细胞凋亡(0.1364±0.0016)亦低于I/R组(0.1525±0.0021),P<0.05。[结论]心肌NOS活性及NO水平变化是心肌再灌注损伤的重要机制之一,17β-雌二醇(E2)(E2)可通过调节心肌NOS活性,维持正常的NO水平,减少细胞凋亡起到保护心肌的作用。

[ Objective] To investigate the effect of E2 on cardiac expression of iNOS, SOD, MDA and apoptosis during myocardial ischemia - reperfusion process and analyze the mechanism of estrogen protective effects during this process. [ Methods] A total of 24 male SD rats were divided into two groups （ischemia -reperfusion （I/R） group and E2 treatment group） randomly. Myocardial I/R models of rats were duplicated by ligating LAD of rat for 20 minutes then reperfusion for 30 min, 120 min and 200 rain respectively. Then the cardiac expression of iNOS, superoxide dismutase （SOD） activity, malondialdehyde （MDA） content and apoptosis were detected at 3 points of reperfusion for the 2 groups respectively. [ Results ] After reperfusion 30, 120 and 200 min, the values of iNOS of the I/R group and E2 treatment group were （ 1050. 474 ± 10. 310）, （677. 639 ± 6. 213）, （529. 000 ± 3. 520） U/mg · prot and （ 1997. 182 ± 6.75 ）, （ 1955. 830 ± 10. 237）, （1754. 375 ± 9. 813） U/mg · prot respectively. The iNOS expressions of the E2 group were all significantly higher than the I/R group at each time point, P 〈0.01. After reperfusion 30 min, SOD activity of the E2 group was （88. 721 ±0. 309） U/mL,significantly higher than the I/R group （61. 337 ± 0. 130） U/mL, P 〈 0.05; compared to the I/R group （36. 648 ± 0. 259） μmol/g, MDA value of the E2 group, （33. 994 ± 0.110） μmol/g, was significantly lower, P 〈 0.05; E2 significantly decreased cardiac apoptosis （0. 1364 ± 0. 0016） comparing with the I/R group （0. 1525 ± 0. 0021 ）, P 〈 0.05. [ Conclusions] The abnormality of myocardial iNOS activity and NO production may be one important factor inducing myocardial ischemia - reperfusion injury. The myocardial protection mechanism of E2 may be attributed to its effect on maintaining normal NO level by regulating myocardial iNOS activity.