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目的研究锌诱导的金属硫蛋白(MT)对阿霉素(DOX)所致心肌细胞凋亡的的抑制作用并探讨其作用机制。方法雄性C57BL小鼠随机分成4组(每组7只),即对照组、锌处理组、给药组和锌预处理给药组。各组小鼠连续2d皮下给予ZnSO4300μmol/kg(锌处理组和锌预处理给药组)或等量生理盐水(对照组和给药组),第3d单次腹腔注射DOX15mg/kg(给药组和锌预处理给药组)或等量生理盐水(对照组和锌处理组)。DOX给药后第4d处死小鼠,采用血红素镉饱和法测定心脏组织MT含量,ELISA法测定心肌凋亡指数,蛋白印迹分析(Westernblot)测定心肌组织凋亡相关蛋白Bax、Bcl-2的表达水平。结果与对照组相比,DOX引起小鼠心脏质量下降10%,且显著引起小鼠心肌细胞凋亡;经锌诱导后,心脏组织MT水平提高约25倍,且MT高表达能抑制DOX引起的凋亡细胞增加;进一步的研究发现,Bax蛋白表达水平在DOX给药后明显升高,而MT高表达抑制了Bax的表达升高;Bcl-2蛋白表达水平各组间的差异无统计学意义。结论锌诱导的MT高表达能抑制DOX引起的心肌细胞凋亡,其作用机制主要与抑制DOX引起的Bax蛋白表达升高以及Bax/Bcl-2比值增加有关。
Objective To study the inhibitory effect of zinc-induced metallothionein (MT) on cardiomyocyte apoptosis induced by doxorubicin (DOX) and its mechanism. Methods Male C57BL mice were randomly divided into 4 groups (7 in each group), namely control group, zinc treatment group, administration group and zinc pretreatment administration group. The mice in each group were given subcutaneous ZnSO4300μmol / kg (zinc treatment group and zinc pretreatment group) or normal saline (control group and administration group) subcutaneously for 2 days, and DOX15mg / kg And zinc pretreatment group) or the same amount of saline (control group and zinc treatment group). The mice were sacrificed on the 4th day after DOX administration, the content of MT in cardiac tissue was determined by heme saturation method, the myocardial apoptosis index was determined by ELISA, and the expression of Bax and Bcl-2 in myocardium was detected by Western blotting Level. Results Compared with the control group, DOX caused a 10% decrease in the heart mass of mice and markedly induced cardiomyocyte apoptosis in mice. After zinc induction, the level of MT in heart tissue increased about 25-fold, and the high expression of MT inhibited DOX-induced Apoptotic cells increased; further study found that Bax protein expression levels were significantly increased after DOX administration, and MT high expression inhibited the expression of Bax increased; Bcl-2 protein expression levels between the groups was not statistically significant . Conclusions Zinc-induced high expression of MT inhibits the apoptosis of cardiomyocytes induced by DOX. The mechanism is mainly related to the inhibition of DOX-induced increase of Bax protein expression and the increase of Bax / Bcl-2 ratio.