妊娠期接触糖皮质激素对子代大鼠心肌血清和糖皮质激素调节的蛋白激酶1表达和心脏功能的印迹效应

目的 揭示妊娠期暴露于糖皮质激素(glucocorticoids,GCs)对子代大鼠心脏功能的印迹效应,探索GCs对子代心肌保护性因子的调节作用及其可能机制.方法 构建妊娠后期GCs暴露大鼠模型,通过2,3,5-氯化三苯基四氮唑(TTC)染色观察子代心肌缺血再灌注损伤后的梗死程度;实时定量PCR检测心肌保护因子血清和糖皮质激素调节的蛋白激酶1(Sgk1)、促肾上腺皮质激素释放激素(CRH)受体2(Crhr2)、CRH家族肽urocortin (Ucn)和Ucn2等基因的表达;蛋白质印迹分析检测SGK1蛋白的表达;亚硫酸氢盐处理后测序确定Sgk1基因启动子的甲基化水平.结果 妊娠期GCs暴露大鼠子代出生时和成年后体质量减轻(P＜0.01),子代雄性大鼠心肌对缺血再灌注损伤的耐受性下降(P＜0.01);SGK1的mRNA和蛋白在子代雄性大鼠心肌中的表达降低(P＜0.01或P＜0.05);Ucn和Ucn2在子代雌性大鼠心肌中的表达下降(P＜0.05);Sgk1基因启动子区域存在多个CpG岛,且近端CpG岛的甲基化水平在妊娠期GCs暴露的子代雄性大鼠心肌中升高(P＜0.01).结论 妊娠期GCs暴露可能通过下调心肌保护因子SGK1的表达对子代雄性大鼠心肌功能产生印迹效应,而Sgk1基因启动子区域CpG岛的高甲基化改变可能是介导GCs对Sgk1的印迹效应的重要机制.

Programming effect of glucocorticoid exposure during rat pregnancy on cardiac functions and expression of serum- and glucocorticoid-regulated protein kinase 1 in offspring

Objective: To investigate the programming effects of excess glucocorticoids exposure during pregnancy on the cardiac functions of adult offspring, as well as the underlying mechanisms. Methods: The infarction areas of hearts were evaluated by TTC staining after ischemia-reperfusion (I/R) injury. The mRNA levels of cardio-protective factors Sgk1, Crhr2, Ucn, and Ucn2 were determined by real-time PCR. The protein level of SGK1 was detected using Western blotting. BSP-sequencing method was employed to determine the methylation status of Sgk1 promoter. Results: The infarction area of hearts after ischemia-reperfusion in the adult males from GCs-exposed rats is significantly larger than that from the vehicle group. The mRNA and protein levels of Sgk1 were decreased in male adults hearts exposed to excess GCs prenatally, whereas Ucn and Ucn2 mRNA expression were decreased in the hearts of female adults exposed to excess GCs prenatally. The proximal CpG island in the Sgk1 promoter is hypermethylated in the heart of adult male offspring exposed to excess GCs during late pregnancy. Conclusion: Excess glucocorticoids exposure during pregnancy causes programming effects on cardiac functions of male adult offspring, potentially via the down-regulation of SGK1 expression in heart, which is largely due to the hypermethylation on Sgk1 promoter.