title: Chronic aldosterone administration causes Nox2-mediated increases in reactive oxygen species production and endothelial dysfunction in the cerebral circulation.
abstract: OBJECTIVE
  An elevated plasma aldosterone level is an independent cardiovascular risk factor. Although excess aldosterone promotes cardiovascular disease, no studies have examined the effect of increased plasma aldosterone on the cerebral circulation. A major source of vascular reactive oxygen species (ROS) during cardiovascular disease is the NADPH oxidases. Because Nox2-containing NADPH oxidase (Nox2 oxidase) is highly expressed in the cerebral endothelium, we postulated that it might contribute to ROS generation and vascular dysfunction in response to aldosterone. Here, we examined the effect of aldosterone and Nox2 oxidase on ROS production and endothelial dysfunction in the cerebral circulation, and whether the effects of aldosterone are exacerbated in aged mice.
  
  
  RESULTS
  In adult (average age ∼24-25 weeks) wild-type and Nox2-deficient (Nox2(/y)) mice, neither vehicle nor aldosterone (0.28  mg/kg per day for 14 days) affected blood pressure (measured using tail-cuff). By contrast, aldosterone treatment reduced dilation of the basilar artery (measured using myography) to the endothelium-dependent agonist acetylcholine in wild-type mice (P < 0.05), but had no such effect in Nox2(/y) mice (P > 0.05). Aldosterone increased basal and phorbol dibutyrate-stimulated superoxide production (measured using L-012-enhanced chemiluminesence) in cerebral arteries from wild-type but not from Nox2(/y) mice. In aged wild-type mice (average age ∼70 weeks), aldosterone treatment increased blood pressure, but had a similar effect on cerebral artery superoxide levels as in adult wild-type mice.
  
  
  CONCLUSIONS
  These data indicate that Nox2 oxidase mediates aldosterone-induced increases in ROS production and endothelial dysfunction in cerebral arteries from adult mice independently of blood pressure changes. Aldosterone-induced hypertension is augmented during aging.
authors.affiliation: aVascular Biology & Immunopharmacology Group, Department of Pharmacology, Monash University, Clayton, Victoria, Australia bDepartments of Internal Medicine and Pharmacology, Cardiovascular Center, The University of Iowa Carver College of Medicine cIowa City Veterans Affairs Healthcare System, Iowa City, Iowa, USA.
authors.forename: Sophocles
authors.initials: S
authors.lastname: Chrissobolis
authors.forename: Grant R
authors.initials: GR
authors.lastname: Drummond
authors.forename: Frank M
authors.initials: FM
authors.lastname: Faraci
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Sobey
mesh_terms: D000367:Age Factors; D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002318:Cardiovascular Diseases / Q000209:etiology / Q000378:metabolism; D002536:Cerebral Arteries / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D008165:Luminol / Q000031:analogs & derivatives; D008297:Male; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000502:physiology*; D051379:Mice; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000172:deficiency / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012307:Risk Factors; D013481:Superoxides / Q000378:metabolism
chemical_list: D008562:Membrane Glycoproteins; D017382:Reactive Oxygen Species; D013481:Superoxides; C081614:L 012; D000450:Aldosterone; D008165:Luminol; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases