NF-кB/Ⅰ-кB在过氧化氢所致心肌细胞损伤中的作用

目的探讨氧化应激损伤心肌细胞的分子机制.方法采用0.5 mmol/L过氧化氢(hydrogen peroxide,H2O2)作用于原代培养的新生大鼠心肌细胞;末端标记检测细胞凋亡;Westernblot检测蛋白质含量;免疫组化检测NF-κB在细胞内的分布.结果①H2O2损伤3 h,心肌细胞死亡率和乳酸脱氢酶(LDH)释放率均较对照组明显升高(P＜0.01);②H2O2损伤24 h,末端标记发现大量凋亡细胞;Westemblot示NF-κB内源性抑制蛋白I-KB(inhibitor KB,I-KB)在H2O2损伤5 min即减少,15 min时减至最低,而后逐渐恢复;免疫组化显示H2O2损伤0.5 h可引起心肌细胞中NF-κB从胞浆向胞核移位;与单纯损伤组比,NF-κB抑制剂吡咯烷二硫代氨基甲酸盐(pyrrolidine dithiocarbamate,PDTC)能明显降低心肌细胞LDH释放率(P＜0.01).结论在H2O2所致心肌细胞损伤中,既有坏死,又有凋亡的发生,而NF-κB/I-κB信号通路的激活可能介导了H2O2所致的心肌细胞损伤.

Role of NF- κB/Ⅰ-κB in cardiomyocyte injury induced by hydrogen peroxide

Objective:This study was designed to investigate the role of NF - κB/I - κB in cardiomyocyte in-jury during the oxidative stress. Methods: Injury of neonatal rat cardiomyocytes was induced by exposure to 0.5mmol/L hydrogen peroxide ( H2 O2 ) for different durations. Cardiomyocyte necrosis and apoptosis were determined by cell death rate, LDH release rate and terminal deoxynucleotidyl transferase - mediated biotin - dUTP nick - end labe-ling (TUNEL) respectively. The change of I- κB was assayed by Western Blot. The translocation of NF-κ B from cytoplasm to nucleus was observed by immunohistochemical analysis. Results: Exposure to 0. 5 mmol/L H2O2 resul-ted in neonatal ratcardiomyocyte necrosis and apoptosis as shown by increase of cell death rate, LDH release rate and TUNEL positivity respectively. Level of I - κB, an endogenous inhibitory protein of NF - κB ,began to decrease after 5 min of H2 O2 treatment, reached nadir at 15 min, and recovered at 1 h. The translocation of NF - κB from cytoplasm to nucleus in cardiomyocytes was observed after exposure to H2 O2 for 0.5 h. Pyrrolidine dithiocarbamate ( PDTC ), an inhibitor of NF - κB, could attenuate H2O2 - induced increase of LDH release rate in cardiomyocyte (P＜ 0.01 ). Conclusion: H2O2 could induce both necrosis and apoptosis of cultured neonatal rat cardiomyocytes, which could be mediated by activation of NF - κB/I - κB pathway.