Abstract |
Overactivity of the renin-angiotensin system, oxidative stress, and cyclooxygenases (COX) in the brain are implicated in the pathogenesis of hypertension. We previously reported that angiotensin-converting enzyme 2 (ACE2) overexpression in the brain attenuates the development of deoxycorticosterone acetate- salt hypertension, a neurogenic hypertension model with enhanced brain renin-angiotensin system and sympathetic activity. To elucidate the mechanisms involved, we investigated whether oxidative stress, mitogen-activated protein kinase signaling and cyclooxygenase (COX) activation in the brain are modulated by ACE2 in neurogenic hypertension. Deoxycorticosterone acetate- salt hypertension significantly increased expression of Nox-2 (+61±5%), Nox-4 (+50±13%), and nitrotyrosine (+89±32%) and reduced activity of the antioxidant enzymes, catalase (-29±4%) and superoxide dismutase (-31±7%), indicating increased oxidative stress in the brain of nontransgenic mice. This increased oxidative stress was attenuated in transgenic mice overexpressing ACE2 in the brain. Deoxycorticosterone acetate- salt-induced reduction of neuronal nitric oxide synthase expression (-26±7%) and phosphorylated endothelial nitric oxide synthase/total endothelial nitric oxide synthase (-30±3%), and enhanced phosphorylation of protein kinase B and extracellular signal-regulated kinase 1/2 in the paraventricular nucleus, were reversed by ACE2 overexpression. In addition, ACE2 overexpression blunted the hypertension-mediated increase in gene and protein expression of COX-1 and COX-2 in the paraventricular nucleus. Furthermore, gene silencing of either COX-1 or COX-2 in the brain, reduced microglial activation and accompanied neuroinflammation, ultimately attenuating Deoxycorticosterone acetate- salt hypertension. Together, these data provide evidence that brain ACE2 overexpression reduces oxidative stress and COX-mediated neuroinflammation, improves antioxidant and nitric oxide signaling, and thereby attenuates the development of neurogenic hypertension.
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Authors | Srinivas Sriramula, Huijing Xia, Ping Xu, Eric Lazartigues |
Journal | Hypertension (Dallas, Tex. : 1979)
(Hypertension)
Vol. 65
Issue 3
Pg. 577-86
(Mar 2015)
ISSN: 1524-4563 [Electronic] United States |
PMID | 25489058
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
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Copyright | © 2014 American Heart Association, Inc. |
Chemical References |
- Antioxidants
- Isoenzymes
- Membrane Proteins
- Desoxycorticosterone Acetate
- Nitric Oxide Synthase
- Ptgs2 protein, mouse
- Cyclooxygenase 1
- Cyclooxygenase 2
- Ptgs1 protein, mouse
- Proto-Oncogene Proteins c-akt
- Peptidyl-Dipeptidase A
- Ace2 protein, mouse
- Angiotensin-Converting Enzyme 2
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Topics |
- Angiotensin-Converting Enzyme 2
- Animals
- Antioxidants
(metabolism)
- Brain
(metabolism)
- Cyclooxygenase 1
(genetics, metabolism)
- Cyclooxygenase 2
(genetics, metabolism)
- Desoxycorticosterone Acetate
(adverse effects)
- Disease Models, Animal
- Encephalitis
(metabolism, prevention & control)
- Gene Silencing
- Hypertension
(chemically induced, metabolism, prevention & control)
- Isoenzymes
(metabolism)
- MAP Kinase Signaling System
(physiology)
- Male
- Membrane Proteins
(genetics, metabolism)
- Mice
- Mice, Transgenic
- Nitric Oxide Synthase
(metabolism)
- Oxidative Stress
(physiology)
- Peptidyl-Dipeptidase A
(metabolism)
- Proto-Oncogene Proteins c-akt
(metabolism)
- Up-Regulation
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