目的 观察乙醛脱氢酶2(ALDH2)对大鼠心肌缺血/再灌注损伤及凋亡的影响以及潜在机制.方法 选择健康雄性SD大鼠40只,随机分成假手术组、激动剂(乙醇)+假手术组、缺血/再灌注组、激动剂+缺血/再灌注组,每组各10只.术前注射乙醇,后建立心肌缺血/再灌注损伤模型;假手术组仅开胸不结扎前降支.每组随机抽取5只用于心肌梗死面积测定,另外5只提取左心室组织进行苏木精-伊红(HE)染色,Western blot测定ALDH2、JNK、p-JNK、Bcl-2和Bax蛋白的表达,TUNEL检测细胞凋亡情况.结果 缺血/再灌注组心肌梗死比例较激动剂+缺血/再灌注组明显增大,(52.51±7.12)% vs. (24.10±5.37)%,差异有统计学意义(P<0.05).假手术组和激动剂+假手术组大鼠心肌纤维排列整齐,形态完整,结构正常.缺血/再灌注组大鼠心肌纤维排列紊乱,间质水肿,组织间隙明显增宽,心肌细胞多处肿胀、溶解断裂,细胞核肿胀,甚至消失;而激动剂+缺血/再灌注组的心肌损伤较轻.缺血/再灌注组ALDH2、Bcl-2表达低于激动剂+缺血/再灌注组[(25.28±3.92) vs. (37.42±7.27),(22.24 ±3.20) vs. (32.04±4.86)],差异有统计学意义(P均<0.05).缺血/再灌注组Bax表达较激动剂+缺血/再灌注组升高[(131.88±16.88)vs. (114.50±5.15)],而Bcl-2/Bax比值较激动剂+缺血/再灌注组降低[(0.17±0.04) vs. (0.28±0.05)],差异有统计学意义(P<0.05).缺血/再灌注组JNK、p-JNK蛋白表达高于激动剂+缺血/再灌注组[(193.03±3.98) vs. (154.17±9.82,(229.16±11.17) vs. (165.57 ±9.30)],p-JNK/JNK比值也高于激动剂+缺血/再灌注组,差异有统计学意义(P均<0.05).缺血/再灌注组和激动剂+缺血/再灌注组细胞凋亡率均高于假手术组和激动剂+假手术组,[(38.36±9.08)%、(16.33±2.29)% vs.(4.76±1.41)%、(5.19±0.62)%],差异有统计学意义(P均<0.05).四组心肌ALDH2表达量与心肌细胞凋亡率呈负相关(r=-0.799,P<0.01),与p-JNK/JNK呈负相关(r=-0.752,P<0.01).结论 ALDH2可能通过抑制JNK信号通路的活性,抑制心肌细胞凋亡,减轻大鼠心肌缺血/再灌注损伤,发挥心肌保护作用.
Objective To observe the influence of aldehyde dehydrogenase 2 (ALDH2) on ischemia reperfusion injury (IRI) and apoptosis of myocardial cells in rats and study potential mechanism. Methods Healthy male SD rats (n=40) were chosen and randomly divided into sham-operation group, agonist (ethanol)+sham-operation group, IRI group and agonist+IRI group (each n=10). Ethanol injection was given to rats and IRI model was established. Only opening chest without anterior descending branch ligation was given to sham-operation group. There were 5 rats were chosen from each group for detecting area of myocardial infarction (MI), and left ventricular tissue was collected from other 5 rats in each group for HE staining. The protein expressions of ALDH2, JNK, p-JNK, Bcl-2 and Bax were detected by using Western blotting assay, and apoptosis was detected by using TUNEL method. Results The proportion of MI was higher in IRI group than that in agonist+IRI group [(52.51±7.12)% vs. (24.10 ±5.37)%, P<0.05]. The structure of heart was normal in sham-operation group and agonist+sham-operation group, and injured seriously in IRI group. The myocardial injury was milder in agonist+IRI group. The expressions of ALDH2 and Bcl-2 were lower in IRI group than those in agonist+IRI group [(25.28±3.92) vs. (37.42±7.27), (22.24±3.20) vs. (32.04±4.86), all P<0.05]. The expression of Bax was higher [(131.88±16.88) vs. (114.50± 5.15)], and expression of Bcl-2/Bax was lower in IRI group than those in agonist+IRI group [(0.17±0.04) vs. (0.28 ±0.05), P<0.05]. The protein expressions of JNK and p-JNK was higher [(193.03±3.98) vs. (154.17±9.82), (229.16±11.17) vs. (165.57±9.30)], and ratio of p-JNK to JNK (p-JNK/JNK) was higher in IRI group than those in agonist+IRI group (all P<0.05). The rate of apoptosis was higher in IRI group and agonist+IRI group than that in sham-operation group and agonist+sham-operation [(38.36±9.08)% and (16.33±2.29)% vs. (4.76±1.41)% and (5.19±0.62)%]. The expression of ALDH2 was negatively correlated to rate of apoptosis (r=-0.799, P<0.01) and p-JNK/JNK (r=-0.752, P<0.01). Conclusion ALDH2 may inhibit apoptosis of myocardial cells, alleviate IRI and play a myocardial protective role through inhibiting activity of JNK signal pathway.