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Mysiewicz SC, Hawks SM, Bukiya AN, Dopico AM. Differential Functional Contribution of BK Channel Subunits to Aldosterone-Induced Channel Activation in Vascular Smooth Muscle and Eventual Cerebral Artery Dilation. Int J Mol Sci 2023; 24:ijms24108704. [PMID: 37240049 DOI: 10.3390/ijms24108704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/03/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
Calcium/voltage-activated potassium channels (BK) control smooth muscle (SM) tone and cerebral artery diameter. They include channel-forming α and regulatory β1 subunits, the latter being highly expressed in SM. Both subunits participate in steroid-induced modification of BK activity: β1 provides recognition for estradiol and cholanes, resulting in BK potentiation, whereas α suffices for BK inhibition by cholesterol or pregnenolone. Aldosterone can modify cerebral artery function independently of its effects outside the brain, yet BK involvement in aldosterone's cerebrovascular action and identification of channel subunits, possibly involved in steroid action, remains uninvestigated. Using microscale thermophoresis, we demonstrated that each subunit type presents two recognition sites for aldosterone: at 0.3 and ≥10 µM for α and at 0.3-1 µM and ≥100 µM for β1. Next, we probed aldosterone on SM BK activity and diameter of middle cerebral artery (MCA) isolated from β1-/- vs. wt mice. Data showed that β1 leftward-shifted aldosterone-induced BK activation, rendering EC50~3 μM and ECMAX ≥ 10 μM, at which BK activity increased by 20%. At similar concentrations, aldosterone mildly yet significantly dilated MCA independently of circulating and endothelial factors. Lastly, aldosterone-induced MCA dilation was lost in β1-/- mice. Therefore, β1 enables BK activation and MCA dilation by low µM aldosterone.
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Affiliation(s)
- Steven C Mysiewicz
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38103, USA
| | - Sydney M Hawks
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38103, USA
| | - Anna N Bukiya
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38103, USA
| | - Alex M Dopico
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38103, USA
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Shikata E, Miyamoto T, Yamaguchi T, Yamaguchi I, Kagusa H, Gotoh D, Shimada K, Tada Y, Yagi K, Kitazato KT, Kanematsu Y, Takagi Y. An imbalance between RAGE/MR/HMGB1 and ATP1α3 is associated with inflammatory changes in rat brain harboring cerebral aneurysms prone to rupture. J Neuroinflammation 2022; 19:161. [PMID: 35725479 PMCID: PMC9210698 DOI: 10.1186/s12974-022-02526-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/24/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND AND PURPOSE An aneurysmal subarachnoid hemorrhage is a devastating event. To establish an effective therapeutic strategy, its pathogenesis must be clarified, particularly the pathophysiology of brain harboring intracranial aneurysms (IAs). To elucidate the pathology in brain harboring IAs, we examined the significance of the receptor for advanced glycation end-products (RAGE)/mineralocorticoid receptor (MR) pathway and Na+/K+-ATPase (ATP1α3). METHODS Ten-week-old female rats were subjected to oophorectomy as well as hypertension and hemodynamic changes to induce IAs, and were fed a high-salt diet. Brain damage in these rats was assessed by inflammatory changes in comparison to sham-operated rats fed a standard diet. RESULTS Six weeks after IA induction (n = 30), irregular morphological changes, i.e., an enlarged vessel diameter and vascular wall, were observed in all of the left posterior cerebral arteries (Lt PCAs) prone to rupture. Approximately 20% of rats had ruptured IAs within 6 weeks. In brain harboring unruptured IAs at the PCA, the mRNA levels of RAGE and MR were higher, and that of ATP1α3 was lower than those in the sham-operated rats (p < 0.05, each). Immunohistochemically, elevated expression of RAGE and MR, and decreased expression of ATP1α3 were observed in the brain parenchyma adjacent to the Lt PCA, resulting in increased Iba-1 and S100B expression that reflected the inflammatory changes. There was no difference between the unruptured and ruptured aneurysm rat groups. Treatment with the MR antagonist esaxerenone abrogated these changes, and led to cerebral and vascular normalization and prolonged subarachnoid hemorrhage-free survival (p < 0.05). CONCLUSIONS Regulation of the imbalance between the RAGE/MR pathway and ATP1α3 may help attenuate the damage in brain harboring IAs, and further studies are warranted to clarify the significance of the down-regulation of the MR/RAGE pathway and the up-regulation of ATP1α3 for attenuating the pathological changes in brain harboring IAs.
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Affiliation(s)
- Eiji Shikata
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan.
| | - Takeshi Miyamoto
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Tadashi Yamaguchi
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Izumi Yamaguchi
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Hiroshi Kagusa
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Daiki Gotoh
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Kenji Shimada
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Yoshiteru Tada
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Kenji Yagi
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Keiko T Kitazato
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Yasuhisa Kanematsu
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Yasushi Takagi
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Tokushima University, Kuramoto-cho, Tokushima, 770-8503, Japan
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Zhao Q, Yan T, Chopp M, Venkat P, Chen J. Brain-kidney interaction: Renal dysfunction following ischemic stroke. J Cereb Blood Flow Metab 2020; 40:246-262. [PMID: 31766979 PMCID: PMC7370616 DOI: 10.1177/0271678x19890931] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Stroke is a leading cause of mortality and morbidity, with long-term debilitating effects. Accumulating evidence from experimental studies as well as observational studies in patients suggests a cross talk between the brain and kidney after stroke. Stroke may lead to kidney dysfunction which can adversely impact patient outcome. In this review article, we discuss the epidemiology and mechanisms of brain–kidney interaction following ischemic stroke. Specifically, we discuss the role of the central autonomic network, autoregulation, inflammatory and immune responses, the role of extracellular vesicles and their cargo microRNA, in mediating brain–kidney interaction following stroke. Understanding the bidirectional nature of interaction between the brain and kidney after cerebral injury would have clinical implications for the treatment of stroke and overall patient outcome.
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Affiliation(s)
- Qiang Zhao
- Tianjin Neurological Institute, Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Tao Yan
- Tianjin Neurological Institute, Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Michael Chopp
- Department of Neurology, Henry Ford Hospital, Detroit, MI, USA.,Department of Physics, Oakland University, Rochester, MI, USA
| | - Poornima Venkat
- Department of Neurology, Henry Ford Hospital, Detroit, MI, USA
| | - Jieli Chen
- Department of Neurology, Henry Ford Hospital, Detroit, MI, USA
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Chen Y, Yu Y, Qiao J, Zhu L, Xiao Z. Mineralocorticoid receptor excessive activation involved in glucocorticoid-related brain injury. Biomed Pharmacother 2019; 122:109695. [PMID: 31812016 DOI: 10.1016/j.biopha.2019.109695] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 11/15/2019] [Accepted: 11/22/2019] [Indexed: 02/05/2023] Open
Abstract
The mechanisms involved in brain damage during chronic glucocorticoid exposure are poorly understood. Since mineralocorticoid receptor (MR) activation has been proven to be important in the pathophysiology of vascular damage and MRs are highly expressed in many brain regions, we hypothesized that the cerebral injury observed in subjects with Cushing syndrome is in part associated with the overactivation of MR. The aim of this study was to determine whether the cerebral injury observed in chronic hyperglucocorticoidemia animal models is related to excessive MR activation. Male SD rats were divided into five groups: vehicle, hydrocortisone (HC, 5 mg/kg/day, i.g.), HC + spironolactone (SL, 20 mg/kg/d in chow), dexamethasone (DXM, 0.25 mg/kg/day, i.g.), and DXM + SL (20 mg/kg/d in chow). Compared to the vehicle-treated group, HC-treated rats had higher blood pressure and higher levels of cerebral vascular fibrosis, cortical/hippocampal atrophy, reactive oxygen species (ROS) production and proinflammatory gene expression. However, in HC-treated animals, treatment with SL markedly alleviated ROS production, cerebral and cerebrovascular morphological changes and inflammation but failed to reduce blood pressure. In contrast, DXM induced no cerebral morphological changes except fibrosis in cerebral vessels, an effect that was not ameliorated by SL treatment. These findings demonstrate that the excessive MR activation observed following chronic hyperglucocorticoidemia exposure contributes to cerebrovascular fibrosis and remodeling and promotes neural apoptosis in the cerebral cortex/hippocampus.
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Affiliation(s)
- Yaxi Chen
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yerong Yu
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
| | - Jingtao Qiao
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Leilei Zhu
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Zhen Xiao
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, Sichuan, China
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Wu F, Lin Y, Liu Q. The emerging role of aldosterone/mineralocorticoid receptors in the pathogenesis of erectile dysfunction. Endocrine 2018; 61:372-382. [PMID: 29721801 DOI: 10.1007/s12020-018-1610-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 04/17/2018] [Indexed: 12/26/2022]
Abstract
PURPOSE Aldosterone is an old hormone that has been discovered for more than fifty years. The clinical application of its receptors' inhibitors, especially spirolactone, has benifited patients for decades worldwide. In this review, we briefly summarized the molecular mechanism of aldosterone/mineralocorticoid receptors (Ald-MRs) signaling in cardiovascular diseases and its emerging role in erectile dysfunction. METHODS We searched PubMed, Web of Science, and Scopus for manuscripts published prior to December 2017 using key words " aldosterone " AND " erectile dysfunction " OR " cardiovascular disease " OR " mineralocorticoid receptors ". Related literature and clinical perspectives were collated, summarized and discussed in this review. RESULTS The increase of reactive oxygen species production, inhibition of endothelial nitric oxide synthase system, and induction of inflammation are ubiquitous in vascular endothelial cells or vascular smooth muscle cells after the activation of Ald-MRs pathway. In addition, in cardiovascular diseases with over-active Ald-MRs signaling, MRs blockade could reverse the injury and improve the prognosis. Notably, multiple studies have correlated aldosterone and MRs to the pathogenesis of erectile function, while the mechanism is largely unperfectly identified. CONCLUSION In conclusion, we summarize the current evidence to highlight the potential role of aldosterone in erectile dysfunction and provide critical insights into the treatment of the disease.
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Affiliation(s)
- Fei Wu
- Department of Urology, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, 250014, China.
| | - Yun Lin
- Department of Urology, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, 250014, China
| | - Qingyong Liu
- Department of Urology, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, 250014, China.
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Ripoll JG, Blackshear JL, Díaz-Gómez JL. Acute Cardiac Complications in Critical Brain Disease. Neurosurg Clin N Am 2018; 29:281-297. [PMID: 29502718 DOI: 10.1016/j.nec.2017.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Acute cardiac complications in critical brain disease should be understood as a clinical condition representing an intense brain-heart crosstalk and might mimic ischemic heart disease. Two main entities (neurogenic stunned myocardium [NSM] and stress cardiomyopathy) have been better characterized in the neurocritically ill patients and they portend worse clinical outcomes in these cases. The pathophysiology of NSM remains elusive. However, significant progress has been made on the early identification of neurocardiac compromise following acute critical brain disease. Effective prevention and treatment interventions are yet to be determined.
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Affiliation(s)
- Juan G Ripoll
- Department of Critical Care Medicine, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - Joseph L Blackshear
- Department of Cardiology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - José L Díaz-Gómez
- Departments of Critical Care Medicine, Anesthesiology and Neurologic Surgery, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
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Ripoll JG, Blackshear JL, Díaz-Gómez JL. Acute Cardiac Complications in Critical Brain Disease. Neurol Clin 2018; 35:761-783. [PMID: 28962813 DOI: 10.1016/j.ncl.2017.06.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Acute cardiac complications in critical brain disease should be understood as a clinical condition representing an intense brain-heart crosstalk and might mimic ischemic heart disease. Two main entities (neurogenic stunned myocardium [NSM] and stress cardiomyopathy) have been better characterized in the neurocritically ill patients and they portend worse clinical outcomes in these cases. The pathophysiology of NSM remains elusive. However, significant progress has been made on the early identification of neurocardiac compromise following acute critical brain disease. Effective prevention and treatment interventions are yet to be determined.
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Affiliation(s)
- Juan G Ripoll
- Department of Critical Care Medicine, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - Joseph L Blackshear
- Department of Cardiology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - José L Díaz-Gómez
- Departments of Critical Care Medicine, Anesthesiology and Neurologic Surgery, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
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Abstract
PURPOSE OF REVIEW The purpose of this study was to summarize recent findings about cardiovascular benefits and safety of aldosterone blockade in patients with end-stage renal disease (ESRD). RECENT FINDINGS It is now well recognized that aldosterone's deleterious cardiovascular impact is not limited to its pressor effect arising from an increase in sodium reabsorption in the kidneys. Aldosterone has also been shown to increase blood pressure by a direct activation of the sympathetic nervous system, to cause endothelial and vascular smooth muscle cell dysfunction, myocardial remodeling and fibrosis, and to have pro-arrhythmogenic actions in the heart. These unconventional extra-renal effects of aldosterone make its blockade feasible and potentially beneficial for patients with ESRD. Accumulating data support the idea that aldosterone antagonism leads to a better blood pressure control, reduction in left ventricular (LV) mass, improved LV function, and reduced all-cause and cardiovascular mortality in ESRD patients. Reassuringly, rates of major adverse events, especially, significant hyperkalemia-the most feared adverse consequence-were low with careful patient selection and monitoring.
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Affiliation(s)
- Radmila Lyubarova
- Division of Cardiology, Department of Medicine, Albany Medical College, Albany, NY, USA
| | - Elvira O Gosmanova
- Nephrology Section, Stratton VA Medical Center, 113 Holland Ave, Albany, NY, 12208, USA.
- Division of Nephrology and Hypertension, Department of Medicine, Albany Medical College, Albany, NY, USA.
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Dinh QN, Drummond GR, Sobey CG, Chrissobolis S. Cell-specific mineralocorticoid receptors: future therapeutic targets for stroke? Neural Regen Res 2016; 11:1230-1. [PMID: 27651763 PMCID: PMC5020814 DOI: 10.4103/1673-5374.189173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Quynh N Dinh
- Vascular Biology & Immunopharmacology Group, Cardiovascular Disease Program and Department of Pharmacology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Grant R Drummond
- Vascular Biology & Immunopharmacology Group, Cardiovascular Disease Program and Department of Pharmacology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Christopher G Sobey
- Vascular Biology & Immunopharmacology Group, Cardiovascular Disease Program and Department of Pharmacology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Sophocles Chrissobolis
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, OH, USA
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Liu S, Zhang Y, Zhao Y, Cui H, Cao C, Guo J. Effects of hypothermia on S100B and glial fibrillary acidic protein in asphyxia rats after cardiopulmonary resuscitation. Cell Biochem Biophys 2016; 71:401-6. [PMID: 25209741 DOI: 10.1007/s12013-014-0212-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The aim of the study was to investigate the effects of hypothermia on S100B and glial fibrillary acidic protein (GFAP) in serum and hippocampus CA1 area in asphyxiated rats after cardiopulmonary resuscitation (CPR). A total of 100 SD rats were designated into four groups: group A, sham operation group; group B, rats received conventional resuscitation; group C, rats received conventional resuscitation and hypothermia at cardiac arrest; group D, rats received conventional resuscitation and hypothermia at 30 min after restoration of spontaneous circulation (ROSC). Rats were then killed by cardiac arrest at 2 and 4 h after ROSC; brain tissue was taken to observe dynamic changes of S100B and GFAP in serum and hippocampus CA1 area. Following ROSC, S100B levels increased from 2 to 4 h in group B, C, and D. In addition, S100B in serum and hippocampus CA1 area was all significantly increased at different time points compared with group A (P < 0.05). Following ROSC, serum S100B level at 2 h in group C was significantly decreased compared with group B, but the difference was not statistically significant (P > 0.05). Moreover, S100B in serum at 4 h after ROSC was significantly decreased (P < 0.05), S100B in cortex was significantly decreased (P < 0.05). The expression of GFAP was also examined. GFAP level in hippocampus CA1 area was significantly decreased in group B, C, and D at 4 h after ROSC compared with group A (P < 0.05). S100B and GFAP were expressed in rat serum and hippocampus CA2 area at early stage after ROSC, which can be used as sensitive markers for brain injury diagnosis and prognosis prediction. Hypothermia is also shown to reduce brain injury after CPR.
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Affiliation(s)
- Sha Liu
- School of Traditional Chinese Medicine, Chongqing Medical University, Jieqing Road, Huxi University City, Chongqing, People's Republic of China
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Dinh QN, Young MJ, Evans MA, Drummond GR, Sobey CG, Chrissobolis S. Aldosterone-induced oxidative stress and inflammation in the brain are mediated by the endothelial cell mineralocorticoid receptor. Brain Res 2016; 1637:146-153. [DOI: 10.1016/j.brainres.2016.02.034] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 01/29/2016] [Accepted: 02/18/2016] [Indexed: 10/22/2022]
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Chronic aldosterone administration causes Nox2-mediated increases in reactive oxygen species production and endothelial dysfunction in the cerebral circulation. J Hypertens 2015; 32:1815-21. [PMID: 24991871 DOI: 10.1097/hjh.0000000000000259] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES 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. METHODS AND 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. CONCLUSION 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.
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The accumulation of brain water-free sodium is associated with ischemic damage independent of the blood pressure in female rats. Brain Res 2015; 1616:37-44. [PMID: 25957792 DOI: 10.1016/j.brainres.2015.04.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 04/25/2015] [Accepted: 04/27/2015] [Indexed: 12/28/2022]
Abstract
Estrogen deficiency worsens ischemic stroke outcomes. In ovariectomized (OVX(+)) rats fed a high-salt diet (HSD), an increase in the body Na(+)/water ratio, which characterizes water-free Na(+) accumulation, was associated with detrimental vascular effects independent of the blood pressure (BP). We hypothesized that an increase in brain water-free Na(+) accumulation is associated with ischemic brain damage in OVX(+)/HSD rats. To test our hypothesis we divided female Wistar rats into 4 groups, OVX(+) and OVX(-) rats fed HSD or a normal diet (ND), and subjected them to transient cerebral ischemia. The brain Na(+)/water ratio was increased even in OVX(+)/ND rats and augmented in OVX(+)/HSD rats. The increase in the brain Na(+)/water ratio was positively correlated with expansion of the cortical infarct volume without affecting the BP. Interestingly, OVX(+) was associated with the decreased expression of ATP1α3, a subtype of the Na(+) efflux pump. HSD increased the expression of brain Na(+) influx-related molecules and the mineralocorticoid receptor (MR). The pretreatment of OVX(+)/HSD rats with the MR antagonist eplerenone reduced brain water-free Na(+) accumulation, up-regulated ATP1α3, down-regulated MR, and reduced the cortical infarct volume. Our findings show that the increase in the brain Na(+)/water ratio elicited by estrogen deficiency or HSD is associated with ischemic brain damage BP-independently, suggesting the importance of regulating the accumulation of brain water-free Na(+). The up-regulation of ATP1α3 and the down-regulation of MR may provide a promising therapeutic strategy to attenuate ischemic brain damage in postmenopausal women.
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