Aberrant DNA methylation of hypothalamic angiotensin receptor in prenatal-programmed hypertension

Malnutrition during pregnancy, which causes prenatal exposure to excessive glucocorticoid, induces adverse metabolic programming leading to hypertension in offspring. Pregnant rats receiving a low-protein diet exhibited moderate downregulation of 11-beta-dehydrogenase isozyme 2, which inactivates corticosterone, in the placenta, resulting in prenatal exposure to excessive corticosterone. In offspring of pregnant rats receiving a low-protein diet or dexamethasone, mRNA expression of angiotensin receptor type 1a (Agtr1a) in the paraventricular nucleus (PVN) of the hypothalamus was upregulated, concurrent with reduced expression of DNA methyltransferase 3a (Dnmt3a), reduced binding of DNMT3a to the Agtr1a promoter, and DNA demethylation, suggesting hypothalamic Agtr1a expression is epigenetically modulated by excess glucocorticoid. Dexamethasone treatment of PVN cells downregulated DNMT3a while upregulating Agtr1a, and decreased DNMT3a binding and DNA demethylation at the Agtr1a promoter. Consistent with Agtr1a upregulation in the hypothalamus, salt loading increased BP in both types of offspring. Even without dexamethasone treatment, hypothalamic neuron-specific DNMT3a-deficient mice, in which Agtr1a was upregulated, exhibited salt-induced BP elevation. By contrast, dexamethasone-treated Agtr1a-deficient mice failed to show salt-induced BP elevation, despite reduced expression of DNMT3a. Thus, epigenetic modulation of hypothalamic angiotensin signaling contributes to salt-sensitive hypertension induced by prenatal glucocorticoid excess in offspring of mothers that are malnourished during pregnancy. The samples were extracted from 12-week-old male offspring whose mothers were treated with vehicle or 200μg/kg dexamethasone at the third trimester.