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目的内质网应激反应(endoplasmic reticulum stress,ERS)介导的凋亡是真核细胞重要凋亡途径之一,通过观察严重烧伤大鼠心肌ERS不同通路蛋白表达变化,探讨其在心肌细胞凋亡中的可能作用。方法雄性7周龄Wistar大鼠64只,体重200～220 g;随机分为两组,每组32只。实验组大鼠背部制备30%体表面积Ⅲ度烫伤;对照组制备假伤模型。伤后1、4、7、14 d两组各处死8只大鼠取心肌组织,透射电镜观察心肌超微结构变化,TUNEL法检测心肌细胞凋亡,Western blot检测ERS相关蛋白,如葡萄糖调节蛋白78(glucose regulated protein 78,GRP 78)、C/EBP同源蛋白(C/EBP-homologous protein,CHOP)、半胱氨酸天冬氨酸蛋白酶12(Caspase 12)剪切体表达变化。结果大鼠均存活至实验结束。透射电镜观察示实验组大鼠心肌细胞呈凋亡改变。伤后各时间点实验组心肌细胞凋亡指数均明显高于对照组(P<0.05),伤后1、4、7 d凋亡指数逐渐升高,14 d时下降,各时间点间比较差异均有统计学意义(P<0.05)。实验组心肌细胞GRP78、CHOP及Caspase 12剪切体蛋白表达持续升高,其中各时间点GRP 78及Caspase 12剪切体表达均较对照组显著升高,差异有统计学意义(P<0.05);除伤后1 d外,其余各时间点实验组CHOP蛋白表达均较对照组升高(P<0.05)。结论严重烧伤后大鼠心肌发生ERS,其中CHOP、Caspase 12介导的凋亡通路活化,ERS可能是心肌细胞凋亡的途径之一。
OBJECTIVE: Endoplasmic reticulum stress (ERS) -mediated apoptosis is one of the important apoptotic pathways of eukaryotic cells. By observing the changes of ERS pathway in severely burned rat myocardium, The possible role of death. Methods Sixty-four male Wistar rats aged 7 weeks, weighing 200-220 g, were randomly divided into two groups of 32 rats. Rats in the experimental group were given 30% body surface area Ⅲ degree scald on the back, and the control group were given sham model. At 1, 4, 7 and 14 days after injury, 8 rats in each group were sacrificed to take myocardial tissue, the ultrastructural changes of myocardial cells were observed by transmission electron microscopy, apoptosis of cardiomyocytes was detected by TUNEL method, and ERS-related proteins such as glucose-regulated protein 78 (GRP 78), C / EBP-homologous protein (CHOP) and Caspase 12 were detected by flow cytometry. Results All rats survived until the end of the experiment. Transmission electron microscopy showed that the experimental group of rat myocardial cells showed apoptotic changes. The apoptotic index of experimental group was significantly higher than that of control group at each time point (P <0.05), the apoptotic index increased gradually at 1, 4 and 7 days after injury, and decreased at 14th day All were statistically significant (P <0.05). The expression of GRP78, CHOP and Caspase 12 in experimental group increased continuously. The expressions of GRP 78 and Caspase 12 in each group were significantly higher than those in control group at each time point, the difference was statistically significant (P <0.05) Compared with the control group, the CHOP protein expression in the experimental group was significantly increased at all other time points (P <0.05) except 1 day after injury. Conclusions ERS occurs in the myocardium of rats after severe burns. Among them, CHOP and Caspase 12 mediate the activation of apoptotic pathway, and ERS may be one of the pathways of cardiomyocyte apoptosis.