湿热应激诱导小鼠心肌细胞凋亡的机制

Mechanism involved in damp-heat induced mice myocardial cell apoptosis

目的探讨湿热应激诱导心肌细胞凋亡的作用机制。方法构建湿热应激小鼠模型,分为湿热应激组(42℃,RH 65%)(H组)和对照组(C组);TUNEL法原位标记凋亡的心肌细胞,EIISA检测AngⅡ的表达水平;体外培养小鼠心肌细胞,分别加入caspase-3抑制剂Z-DEVD-FMK和P38 MAPK抑制剂SB203580共培养24 h,随后加入AngⅡ共培养24 h;Annexin V-FITC凋亡试剂盒检测细胞凋亡率;Western blot检测P38 MAPK及caspase-3的表达水平。结果湿热应激条件导致小鼠心肌细胞凋亡率明显高于常规组,且伴随有大量AngⅡ的生成(P<0.05);体外实验证实,AngⅡ能够剂量依赖性的诱导心肌细胞凋亡,同时诱导caspase-3和P38 MAPK的活化;Z-DEVD-FMK预处理明显抑制Ang 1诱导的心肌细胞凋亡,表明AngⅡ主要通过caspase-3活化途径来诱导心肌细胞凋亡;此外,SB203580可抑制AngⅡ诱导的caspase-3的表达。结论湿热应激诱发心肌细胞凋亡主要是通过AngⅡ诱导的P38 MAPK-caspase-3通路来实现的。

Objective To explore the mechanism of damp-heat induced mice myocardial cell apoptosis. Methods In this study, mice was exposed to damp-heat （42℃, RH 65% ） （ H group） environment or room temperature （ C group）. The myocardial cell apoptosis rates in tissues were analyzed by TUNEL staining. The expression levels of Ang II were detected by EIISA assay. Cardiomyoeytes of rats with 1 day were pretreated with caspase-3 inhibitor Z- DEVD-FMK, or P38 MAPK inhibitor SB203580, for 24 h, followed by culturing with the indicated dose of Ang Ⅱ. AnnexinV-FITC was used to analyze cell apoptosis ratio. In addition, the expression of caspase-3 and P38 MAPK was assessed by Western blot. Results The rates of cell apoptosis and Ang Ⅱ expression levels in H group were significantly higher than those in C group （ P 〈 0. 05 ）. In vitro, Ang Ⅱ dose-dependently induced cardiomyo- eytes apoptosis, accompany with the up-regulation of caspase-3 and P38 MAPK expression. When preconditioning with Z-DEVD-FMK, the apoptotie ratio of cardiomyocytes was significantly attenuated in Ang lI -treated group, im- plying that Ang Ⅱ triggered cell apoptosis in caspase-3-depedent manner. Additionally, pretreatment with SB203580 dramatically abrogated caspase-3 expression induced by Ang Ⅱ. Conclusions Damp-heat environmentinduced cardiomyocytes apoptosis by Ang Ⅱ-activated P38 MAPK-caspase-3 pathway. Consequently, Ang Ⅱ may be a potential target for innovative strategies against cardiovascular diseases induced by Damp-heat environment.