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目的:观察PPARγ激动剂吡格列酮对在体大鼠心肌缺血/再灌注(I/R)心肌细胞凋亡和线粒体超微结构的影响以及其可能机制。方法:将42只SD大鼠随机分为假手术组(对照组)、I/R组、吡咯列酮预处理组(预处理组)。I/R组、预处理组于I/R前24 h分别由尾静脉注射相应溶媒(0.9%氯化钠溶液)及吡格列酮(3 mg/kg)。对照组不结扎前降支,4 h后取出心脏;余2组结扎前降支30 min,再灌注4 h后取出心脏。每组取8只,用透射电镜观察心肌线粒体的超微结构改变,采用TUNEL法和免疫组化法检测各组缺血心肌细胞凋亡和Bcl-2、Bax、caspase-3蛋白的表达,RT-PCR法测p38 MAPK和JNK的mRNA表达;Western blot法测核转录因子-κBp65(NFκB p65)蛋白水平的表达;每组取6只,行心肌梗死面积测定。结果:①与I/R组相比,预处理组线粒体损伤程度明显减轻,梗死面积明显减少;②与I/R组相比,预处理组能明显增加Bcl-2蛋白的阳性细胞指数(P<0.05),降低心肌细胞凋亡率(P<0.05)及Bax、caspase-3蛋白的阳性细胞指数(P<0.05);③与对照组相比,I/R组p38 MAPK和JNK的mRNA表达水平及NFκB p65蛋白表达水平明显增加(P<0.05);与I/R组相比,预处理组能抑制以上水平的过度表达(P<0.05)。结论:吡格列酮预处理可通过保护心肌线粒体结构,减少心肌细胞凋亡起到抗I/R损伤作用,该保护作用机制可能与下调p38 MAPK和JNK的mRNA表达及NFκB p65蛋白表达活性有关。
Objective: To investigate the effect of PPARγ agonist pioglitazone on myocardial cell apoptosis and mitochondrial ultrastructure in myocardial ischemia / reperfusion (I / R) rats and its possible mechanism. Methods: Forty-two SD rats were randomly divided into sham-operated group (control group), I / R group and pyrrolnitril pretreatment group (pretreatment group). In the I / R group and the pretreatment group, the corresponding vehicle (0.9% sodium chloride solution) and pioglitazone (3 mg / kg) were respectively injected into the caudal vein 24 hours before I / R. In the control group, the anterior descending branch was not ligated and the heart was withdrawn after 4 hours. The other two groups were descending for 30 minutes before ligation, and then the heart was withdrawn 4 hours later. The ultrastructural changes of myocardial mitochondria were observed by transmission electron microscopy. The apoptosis and expressions of Bcl-2, Bax and caspase-3 in ischemic cardiomyocytes were detected by TUNEL and immunohistochemistry. RT The expression of p38 MAPK and JNK mRNA was detected by PCR and the expression of NF-κB p65 protein was detected by Western blot. The area of myocardial infarction was measured in 6 rats in each group. Results: Compared with I / R group, pretreatment group mitochondrial damage significantly reduced, infarct size significantly reduced; ② Compared with I / R group, pretreatment group can significantly increase the Bcl-2 protein positive cell index (P (P <0.05), and decreased the apoptotic rate of cardiomyocytes (P <0.05) and the positive cells index of Bax and caspase-3 (P <0.05); ③ Compared with the control group, the mRNA expressions of p38 MAPK and JNK (P <0.05). Compared with I / R group, the pretreatment group could inhibit the over expression of NFκB p65 protein (P <0.05). CONCLUSION: Pioglitazone preconditioning can protect myocardium mitochondrial structure and decrease cardiomyocyte apoptosis against I / R injury. The mechanism may be related to the down-regulation of p38 MAPK and JNK mRNA expression and NFκB p65 protein expression.