Programming effect of glucocorticoid exposure during rat pregnancy on cardiac functions and expression of serum- and glucocorticoid-regulated protein kinase 1 in offspring / 第二军医大学学报

ABSTRACT

Objective To investigate the programming effects of glucocorticoids (GCs) exposure during rat pregnancy on the cardiac functions of adult offspring, so as to explore the cardiac protective effect of GCs and the underlying mechanisms. Methods Advanced pregnancy GCs exposure model was established with rats. The infarction degrees of myocardium of offspring rats were evaluated by 2,3,5-triphenyltetrazolium chloride (TTC) staining after ischemia-reperfusion (I/R) injury. The mRNA levels of cardio-protective factors serum- and glucocorticoid-regulated protein kinase 1(Sgk1), corticotropin-releasing hormone receptor 2 (Crhr2), urocortin (Ucn), and Ucn2 were determined by real-time PCR. The protein level of SGK1 was detected using Western blotting analysis. Bisulfite sequencing PCR (BSP) was employed to determine the methylation level of Sgk1 promoter. Results The body mass of the offsprings of GCs-exposed pregnant rats were significantly lower than that of the normal saline-injected pregnant rats (P<0.01). The ratio between infarction area and risk area of hearts after ischemia-reperfusion in the male adult offspring from GCs-exposed group was significantly larger than that from the vehicle group(P<0.01). The mRNA and protein levels of SGK1 were significantly decreased in male adult offspring hearts exposed to GCs prenatally (P<0.01, P<0.05), whereas Ucn and Ucn2 mRNA expressions were significantly decreased in the hearts of female adult offspring exposed to GCs prenatally (P<0.05). There were multiple CpG islands in Sgk1 promoter, with the proximal CpG island in the Sgk1 promoter being significantly hypermethylated in the heart of adult male offspring exposed to GCs during late pregnancy (P<0.01). Conclusion GCs exposure during pregnancy can cause programming effects on cardiac functions of male adult offspring in rats, probably via the down-regulation of SGK1 expression in the heart, which is largely due to the hypermethylation on Sgk1 promoter.