丙氨酰谷氨酰胺在大鼠心肌梗死中的保护作用及其机制

Protective effect of alanyl glutamine on myocardial infarction in rats and its mechanism

摘要:

目的 研究丙氨酰谷氨酰胺(Ala-Gln)在大鼠心肌梗死中的作用,并探讨其可能的机制。方法 将36只SPF级雄性Wistar大鼠按随机数表法分为4组,即假手术组、心肌梗死模型组(模型组)、心肌梗死+Ala-Gln[0.75mg/(kg·d)]组(治疗组)、心肌梗死+槲皮素[100mg/(kg·d)]+Ala-Gln[0.75mg/(kg·d)]+二甲基亚砜(DMSO)组(槲皮素组),每组9例。模型组、治疗组、槲皮素组造模成功后,治疗组、槲皮素组继续给予相应处理至第7天时处死大鼠,假手术组给予上述各组等量生理盐水。HE染色法观察心肌梗死情况,直接称重法计算心肌梗死面积,免疫组织化学法观察心肌组织中热休克蛋白70(HSP70)表达情况并进行半定量分析,化学比色法检测血清心肌酶(AST、CK-MB、CK)、丙二醛(MDA)活性和超氧化物歧化酶(SOD)水平。采用SPSS 13.0 软件对数据进行分析。结果 模型组、治疗组、槲皮素组心肌梗死质量百分比分别为(0.241±0.054)%、(0.165±0.372)%、(0.248±0.035)%,与假手术组的(0.010±0.002)%比较,差异有统计学意义(P＜0.01)；治疗组心肌梗死质量百分比较模型组和槲皮素组显著缩小(均P＜0.01)。假手术组、模型组、槲皮素组HSP70表达水平分别为(0.154±0.036)、(0.151±0.033)、(0.151±0.025)ng/ml,组间比较差异无统计学意义(P＞0.05)；治疗组HSP70含量为(0.286±0.056)ng/ml,较其余各组均增加,差异有统计学意义(P＜0.01)。与假手术组比较,模型组、治疗组、槲皮素组中CK、AST、LDH均升高(均P＜0.01),而治疗组CK、AST、LDH低于模型组和槲皮素组(均P＜0.01)。与假手术组相比,模型组和槲皮素组MDA水平升高(P＜0.05),SOD水平下降(P＜0.05)；而治疗组MDA水平较模型组和槲皮素组下降(P＜0.05),SOD水平较模型组和槲皮素组升高(P＜0.05)。结论 Ala-Gln对大鼠心肌梗死具有保护作用,其机制可能与诱导HSP70表达、降低MDA活性、升高SOD水平、增强心肌细胞的抗氧化能力、降低活性自由基的损伤等有关。

Abstract:

Objective To explore the role of alanyl-glutamine (Ala-Gln) in myocardial infarction and its possible mechanism. Methods Thirty-six SPF male Wistar rats were randomized into four groups (n=9 each):sham operation group, model group (myocardial ischemic group), treatment group treated with isoproterenol [ISO, 5mg/(kg·d)]+Ala-Gln [0.75mg/(kg·d)], and quercetin group treated with ISO[5mg/(kg·d)]+quercetin [100mg/(kg·d)] +Ala-Gln [0.75mg/(kg·d)]+dimethylsulfoxide. After successful modeling, the treatment and quercetin groups were treated for 7 days,while the sham operation group were treated with the same amount of saline. The rats were sacrificed after 7 days. HE staining was used to observe myocardial ischemic necrosis, area of myocardial ischemic necrosis was calculated by direct weighing; immunohistochemical method was used to observe the expression and distribution of heat shock protein 70 (HSP70) and semi-quantitative analysis was performed; and chemical colorimetric method was used to detect the activities of serum myocardial creatases (aspartate aminotransferase, AST; lactate dehydrogenase, LDH; creatine kinase, CK) and malonaldehyde (MDA), and the level of superoxide dismutase (SOD). SPSS statistics 13.0 was used for data analysis. Results The percentage of myocardial infarction mass in model group [(0.241 ± 0.054)%], treatment group [(0.165 ± 0.372)]% and quercetin group [(0.248 ± 0.035)%] was statistically significantly different with that of the sham operation group [(0.01 ± 0.002)%,P＜0.01], and the mass of myocardial infarction in the treatment group was significantly smaller than that in the model group and quercetin group (P＜0.01). There was no significant difference in the expression levels of HSP70 between the sham operation group (0.154 ± 0.036), model group (0.151 ± 0.033) and quercetin group [(0.151 ± 0.025), P>0.05], but that of the treatment group (0.286 ± 0.056) was significantly higher than those of the other groups (P＜0.01). Compared with the sham operation group, CK, AST and LDH increased in model group, treatment group and quercetin group (P＜0.01), and they were lower in the treatment group than in the model group and the quercetin group (P＜0.01). Compared with the sham operation group, MDA in the model group and quercetin group increased (P＜0.05), and SOD decreased (P＜0.05). MDA was lower and SOD was higher (P＜0.05 for both) in the treatment group than that in the model group and quercetin group. Conclusion Ala-Gln has a protective effect on myocardial infarction in rats. Its mechanism may be related to the induction of HSP70 expression, reduction of MDA activity and increase of SOD level, thus enhancing the antioxidant capacity of cardiomyocytes and reducing the damage of active free radicals.