目的 探讨甘蔗叶多糖对心肌梗死大鼠心肌细胞凋亡的抑制作用及其机制.方法 结扎大鼠冠状动脉左前降支建立大鼠心肌梗死模型,造模成功后将30只大鼠随机分为模型对照组(MI组)、甘蔗叶多糖处理组(SLP组),另设假手术组(Sham组),Sham组只穿线未予结扎.造模后第1天开始连续4周灌胃,SLP组灌入浓度为4 mg/mL甘蔗叶多糖溶液,剂量为1 mL/100 g大鼠体质量,MI组、Sham组灌入相同剂量的生理盐水.4周后开胸取大鼠心脏,采用TUNEL检测梗死边缘区心肌组织细胞凋亡并进行HE染色,采用实时荧光定量PCR检测梗死边缘区组织BCL-2、BAX、Caspase-3 mRNA表达,采用Western blotting检测梗死边缘区组织p-AKT/AKT、p-PI3K/PI3K蛋白表达.结果 Sham组未见心肌细胞凋亡,MI组与SLP组梗死边缘区均有心肌细胞凋亡,Sham组、MI组、SLP组的凋亡率分别为0.017%±0.007%、0.307%±0.048%、0.109%±0.034%,各组间心肌细胞凋亡指数差异均有统计学意义(P均<0.05);与Sham组比较,MI组和SLP组心肌细胞凋亡指数升高,而SLP组相对MI组心肌细胞凋亡指数降低(P均<0.05);与Sham组比较,MI组中BAX、BCL-2、Caspase-3 mRNA表达升高(P均<0.05);与MI组比较,SLP组中BCL-2 mRNA表达升高,BAX、Caspase-3 mRNA表达降低(P均<0.05);与Sham组比较,MI组中p-AKT/AKT、p-PI3K/PI3K蛋白表达降低(P均<0.05).与MI组比较,SLP组中p-AKT/AKT、p-PI3K/PI3K表达升高(P均<0.05).结论 甘蔗叶多糖能抑制大鼠心肌梗死后心肌细胞凋亡,其机制可能与增加抑制凋亡基因BCL-2的表达,减少促凋亡基因BAX、Caspase3的表达,上调p-AKT/AKT、p-PI3K/PI3K蛋白的表达有关.%Objective To investigate the inhibitory effects of polysaccharide from sugarcane leaves on the cardiomyo -cyte apoptosis in rats withmyocardial infarction(MI).Methods We established the MI models by ligating the left anterior descending(LAD)of rats, and then 30 rats were randomly divided into themodel control group(MI group), sugarcane leaf polysaccharide group(SLP group), in addition, sham operation group was set, however, the rats in the sham group were only threaded without ligation.The rats in the SLP group were fed with 4 mg/mL SLP solution,and the rats in the MI group and sham group were fed with the same volume of normal saline.After 4 weeks,the rat's heart was obtained by thora-cotomy,we measured the myocardial apoptosis in the infarct marginal zone by TUNEL and performed HE staining,then we detected the gene expression of BCL-2,BAX,and Caspase3 by real-time PCR,detected the protein expression of p-AKT/AKT and p-PI3K /PI3K at the edge of myocardial infraction by Western blotting.Results The apoptosis in rats of the sham group was not detected,but was detected in the marginal zone of the MI group and SLP group.The apoptotic index of the sham group,MI group,and SLP group were 0.017%±0.007%,0.307%±0.048%,and 0.109%±0.034%, re-spectively.There was significant difference in the apoptotic index of myocardial cells between every two groups(P <0.05).Compared with the sham group.myocardial apoptosis index increased in the MI group and SLP group,but myocar-dial apoptosis index in the SLP group was lower than that in the MI group(all P<0.05).Compared with the sham group, BAX,BCL-2,and Caspase-3 increased in the MI group(P<0.05).Compared with the MI group,the expression of BCL-2 mRNA increased,while the expression of BAX and Caspase-3 mRNA decreased in the SLP group(all P<0.05).Com-pared with the sham group, the protein expression of p-AKT/AKT and p-PI3K/PI3K decreased in the MI group(P<0.05).Compared with the MI group,the expression of p-AKT/AKT and p-PI3K/PI3K increased in the SLP group(both P<0.05).Conclusions SLP could significantly inhibit the apoptosis of myocardial cells after MI,and its mechanism may be that SLP may increase the expression of the anti-apoptosis gene BCL-2, decrease the expression of pro-apoptosis gene BAX,Caspase-3,and up-regulate the expression of p-AKT/AKT and p-PI3K/PI3K protein.
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