title: Glucocorticoid effects on the programming of AT1b angiotensin receptor gene methylation and expression in the rat.
abstract: Adverse events in pregnancy may 'programme' offspring for the later development of cardiovascular disease and hypertension. Previously, using a rodent model of programmed hypertension we have demonstrated the role of the renin-angiotensin system in this process. More recently we showed that a maternal low protein diet resulted in undermethylation of the At1b angiotensin receptor promoter and the early overexpression of this gene in the adrenal of offspring. Here, we investigate the hypothesis that maternal glucocorticoid modulates this effect on fetal DNA methylation and gene expression. We investigated whether treatment of rat dams with the 11beta-hydroxylase inhibitor metyrapone, could prevent the epigenetic and gene expression changes we observed. Offspring of mothers subjected to a low protein diet in pregnancy showed reduced adrenal Agtr1b methylation and increased adrenal gene expression as we observed previously. Treatment of mothers with metyrapone for the first 14 days of pregnancy reversed these changes and prevented the appearance of hypertension in the offspring at 4 weeks of age. As a control for non-specific effects of programmed hypertension we studied offspring of mothers treated with dexamethasone from day 15 of pregnancy and showed that, whilst they had raised blood pressure, they failed to show any evidence of Agtr1b methylation or increase in gene expression. We conclude that maternal glucocorticoid in early pregnancy may induce changes in methylation and expression of the Agtr1b gene as these are clearly reversed by an 11 beta-hydroxylase inhibitor. However in later pregnancy a converse effect with dexamethasone could not be demonstrated and this may reflect either an alternative mechanism of this glucocorticoid or a stage-specific influence.
authors.affiliation: Centre for Endocrinology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.
authors.forename: Irina
authors.initials: I
authors.lastname: Bogdarina
authors.forename: Andrea
authors.initials: A
authors.lastname: Haase
authors.forename: Simon
authors.initials: S
authors.lastname: Langley-Evans
authors.forename: Adrian J L
authors.initials: AJ
authors.lastname: Clark
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure / Q000187:drug effects; D019175:DNA Methylation / Q000187:drug effects*; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology; D004044:Dietary Proteins / Q000008:administration & dosage; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D005938:Glucocorticoids / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008797:Metyrapone / Q000008:administration & dosage / Q000494:pharmacology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D017208:Rats, Wistar; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013252:Steroid 11-beta-Hydroxylase / Q000037:antagonists & inhibitors
chemical_list: D004044:Dietary Proteins; D004791:Enzyme Inhibitors; D005938:Glucocorticoids; D044140:Receptor, Angiotensin, Type 1; D003907:Dexamethasone; D013252:Steroid 11-beta-Hydroxylase; D008797:Metyrapone