title: Glucocorticoid modulates angiotensin II receptor expression patterns and protects the heart from ischemia and reperfusion injury.
abstract: Glucocorticoid regulates angiotensin II receptor (ATR) expression via activating glucocorticoid receptors and binding to glucocorticoid response elements. The regulation of ATR by glucocorticoids in the context of myocardial injury from ischemia/reperfusion (I/R) is yet to be elucidated. The present study determined the role of ATR in glucocorticoid-induced cardiac protection. Adult male rats were administered once a day i.p. 1 mg/kg/day dexamethasone or dexamethasone plus 10 mg/kg/day RU486 for 5 days. Hearts were then isolated and subjected to I/R injury in a Langendorff preparation. Dexamethasone treatment significantly decreased I/R injury and improved post-ischemic recovery of cardiac function. Dexamethasone increased glucocorticoid receptor binding to glucocorticoid response elements at AT1aR and AT2R promoters, resulting in a significant increase in expression of AT1R protein but a decrease in AT2R expression in the heart. In addition, dexamethasone treatment significantly increased PKCε expression and p-PKCε protein abundance. These dexamethasone-mediated effects were blocked by RU486. More importantly, blockade of AT1R and AT2R with losartan and PD123319 abrogated dexamethasone-induced protection of the heart from I/R injury. The results indicate that glucocorticoid promotes a cardioprotective phenotype associated with the upregulation of AT1R and PKCε and downregulation of AT2R in the heart.
authors.affiliation: Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, United States of America.
authors.forename: Qin
authors.initials: Q
authors.lastname: Xue
authors.affiliation: Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, United States of America.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Patterson
authors.affiliation: Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, United States of America.
authors.forename: Daliao
authors.initials: D
authors.lastname: Xiao
authors.affiliation: Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, United States of America.
authors.forename: Lubo
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000818:Animals; D047369:Chromatin Immunoprecipitation; D003907:Dexamethasone / Q000494:pharmacology*; D015536:Down-Regulation; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation / Q000187:drug effects*; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D011401:Promoter Regions, Genetic; D051744:Protein Kinase C-epsilon / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D011945:Receptors, Angiotensin / Q000235:genetics* / Q000378:metabolism; D015427:Reperfusion Injury / Q000517:prevention & control*; D015854:Up-Regulation
chemical_list: D011945:Receptors, Angiotensin; D003907:Dexamethasone; D051744:Protein Kinase C-epsilon