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Sutovska H, Molcan L, Majzunova M, Sykora M, Kopkan L, Zeman M. Mineralocorticoid receptor blockade protects the kidneys but does not affect inverted blood pressure rhythm in hypertensive transgenic (mRen-2)27 rats. Mol Cell Endocrinol 2023; 572:111967. [PMID: 37210027 DOI: 10.1016/j.mce.2023.111967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/17/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023]
Abstract
Aldosterone regulates blood pressure (BP) through water and sodium balance. In our study, we studied if continuous treatment with a mineralocorticoid receptor antagonist, spironolactone (30 mg/kg/day) for 20 days can: 1) attenuate hypertension development and restore inverted 24-h BP rhythm in hypertensive transgenic (mRen-2)27 rats (TGR) measured by telemetry; 2) improve function of the kidneys and heart; 3) be protective against high salt load (1% in water) by mitigating oxidative injury and improving kidney function. Spironolactone decreased albuminuria and 8-isoprostane in normal and salt load conditions in BP-independent effects. Salt load increased BP, impaired autonomic balance, suppressed plasma aldosterone level and increased natriuresis, albuminuria and oxidative injury in TGR. Spironolactone did not restore the inverted 24-h rhythm of BP in TGR, therefore, mineralocorticoids are not crucial in regulation of BP daily profile. Spironolactone improved kidney function, decreased oxidative stress and was protective against high salt load in the BP-independent manner.
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Affiliation(s)
- Hana Sutovska
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Lubos Molcan
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Miroslava Majzunova
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Matus Sykora
- Centre of Experimental Medicine, Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovak Republic.
| | - Libor Kopkan
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic.
| | - Michal Zeman
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
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Kawarazaki W, Fujita T. Role of Rho in Salt-Sensitive Hypertension. Int J Mol Sci 2021; 22:ijms22062958. [PMID: 33803946 PMCID: PMC8001214 DOI: 10.3390/ijms22062958] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/09/2021] [Accepted: 03/12/2021] [Indexed: 12/21/2022] Open
Abstract
A high amount of salt in the diet increases blood pressure (BP) and leads to salt-sensitive hypertension in individuals with impaired renal sodium excretion. Small guanosine triphosphatase (GTP)ase Rho and Rac, activated by salt intake, play important roles in the pathogenesis of salt-sensitive hypertension as key switches of intracellular signaling. Focusing on Rho, high salt intake in the central nervous system increases sodium concentrations of cerebrospinal fluid in salt-sensitive subjects via Rho/Rho kinase and renin-angiotensin system activation and causes increased brain salt sensitivity and sympathetic nerve outflow in BP control centers. In vascular smooth muscle cells, Rho-guanine nucleotide exchange factors and Rho determine sensitivity to vasoconstrictors such as angiotensin II (Ang II), and facilitate vasoconstriction via G-protein and Wnt pathways, leading to increased vascular resistance, including in the renal arteries, in salt-sensitive subjects with high salt intake. In the vascular endothelium, Rho/Rho kinase inhibits nitric oxide (NO) production and function, and high salt amounts further augment Rho activity via asymmetric dimethylarginine, an endogenous inhibitor of NO synthetase, causing aberrant relaxation and increased vascular tone. Rho-associated mechanisms are deeply involved in the development of salt-sensitive hypertension, and their further elucidation can help in developing effective protection and new therapies.
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Sueta D, Yamamoto E, Tsujita K. Mineralocorticoid Receptor Blockers: Novel Selective Nonsteroidal Mineralocorticoid Receptor Antagonists. Curr Hypertens Rep 2020; 22:21. [PMID: 32114686 DOI: 10.1007/s11906-020-1023-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE OF REVIEW Recently, nonsteroidal mineralocorticoid receptor (MR) antagonists (MRAs), which have been proposed to be called MR blockers (MRBs), have become available for clinical use, but their clinical role is unknown. We reviewed the clinical roles of MRAs and MRBs based on previous knowledge and as demonstrated in representative clinical trials. RECENT FINDINGS Steroidal MRAs, such as spironolactone and eplerenone, inhibit the action of aldosterone and cortisol in MRs expressed in several organs and cell types, and accumulating clinical studies have revealed that they exert hypotensive and cardiorenal protective effects. Recently, MRBs, including finerenone and esaxerenone, have been developed and are expected to lower the risk of hyperkalemia, which is common when steroidal MRAs are used. Although the differences between MRAs and MRBs in clinical practice have not yet been established, further studies in this field are expected to broaden our understanding. MRBs exert antihypertensive and cardiorenal protective effects, and their potency is thought to be far superior to that of MRAs, because MRBs have both strong MR inhibitory action and high selectivity. Thus, MRBs could be a promising agent for the treatment of hypertension and cardiorenal, cerebral, and metabolic disorders.
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Affiliation(s)
- Daisuke Sueta
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto City, 860-8556, Japan.
| | - Eiichiro Yamamoto
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto City, 860-8556, Japan
| | - Kenichi Tsujita
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto City, 860-8556, Japan
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Wang HW, Ahmad M, Jadayel R, Najjar F, Lagace D, Leenen FHH. Inhibition of inflammation by minocycline improves heart failure and depression-like behaviour in rats after myocardial infarction. PLoS One 2019; 14:e0217437. [PMID: 31233508 PMCID: PMC6590948 DOI: 10.1371/journal.pone.0217437] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 05/10/2019] [Indexed: 11/29/2022] Open
Abstract
RATIONALE Patients with heart failure have an increased incidence of depression. Central and peripheral inflammation play a major role in the pathophysiology of both heart failure and depression. AIM Minocycline is an antibiotic that inhibits microglia activation and release of pro-inflammatory cytokines. We assessed effects of minocycline on extent of heart failure and depression at 2 and 8 weeks post myocardial infarction. METHODS/RESULTS Male Wistar rats were randomly divided into 3 groups: (i) sham + vehicle; (ii) MI + vehicle; and (iii) MI + minocycline with n/group of 8, 9 and 9 at 2 weeks, and 10, 16, 8 at weeks, respectively. Oral minocycline (50 mg/kg/day) or vehicle started 2 days before surgery. Depression-like behaviour was assessed with sucrose preference and forced swim tests, and cardiac function with echo and hemodynamics. After myocardial infarction, microglia activation and plasma/brain pro-inflammatory cytokines increased, which were mostly prevented by minocycline. At 8 weeks, cardiac dysfunction was attenuated by minocycline: infarct size (MI + Vehicle 29±1, MI + Min 23±1%), ejection fraction (Sham 80±1, MI + Vehicle 48±2, MI + Min 58±2%) and end diastolic pressure (Sham 3.2±0.3, MI + Vehicle 18.2±1.1, MI + Min 8.5±0.9 mm Hg). Depression-like behaviour was significantly improved by minocycline in sucrose preference test (% Sucrose Intake: Sham 96±1, MI + Vehicle 78±2, MI + Min 87±2) and forced swim test (% Immobile: Sham 40±4, MI + Vehicle 61±3, MI + Min 37±6). CONCLUSION Rats post myocardial infarction develop systemic inflammation, heart failure and depression-like behaviour that are all attenuated by minocycline. Targeting (neuro) inflammation may represent new therapeutic strategy for patients with heart failure and depression.
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Affiliation(s)
- Hong-Wei Wang
- Brain and Heart Research Group, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Monir Ahmad
- Brain and Heart Research Group, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Rami Jadayel
- Brain and Heart Research Group, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Fatimah Najjar
- Brain and Heart Research Group, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Diane Lagace
- Neuroscience Research Program, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Frans H. H. Leenen
- Brain and Heart Research Group, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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Yu Y, Wei SG, Zhang ZH, Weiss RM, Felder RB. ERK1/2 MAPK signaling in hypothalamic paraventricular nucleus contributes to sympathetic excitation in rats with heart failure after myocardial infarction. Am J Physiol Heart Circ Physiol 2016; 310:H732-9. [PMID: 26801309 DOI: 10.1152/ajpheart.00703.2015] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 01/11/2016] [Indexed: 02/03/2023]
Abstract
Brain MAPK signaling pathways are activated in heart failure (HF) induced by myocardial infarction and contribute to augmented sympathetic nerve activity. We tested whether decreasing ERK1/2 (also known as p44/42 MAPK) signaling in the hypothalamic paraventricular nucleus (PVN), a forebrain source of presympathetic neurons, would reduce the upregulation of sympathoexcitatory mediators in the PVN and augmented sympathetic nerve activity in rats with HF. Sprague-Dawley rats underwent left anterior descending coronary artery ligation to induce HF, with left ventricular dysfunction confirmed by echocardiography. One week after coronary artery ligation or sham operation, small interfering (si)RNAs targeting ERK1/2 or a nontargeting control siRNA was microinjected bilaterally into the PVN. Experiments were conducted 5-7 days later. Confocal images revealed reduced phosphorylated ERK1/2 immunofluorescence in the PVN of HF rats treated with ERK1/2 siRNAs compared with HF rats treated with control siRNA. Western blot analysis confirmed significant reductions in both total and phosphorylated ERK1/2 in the PVN of HF rats treated with ERK1/2 siRNAs along with reduced expression of renin-angiotensin system components and inflammatory mediators. HF rats treated with ERK1/2 siRNAs also had reduced PVN neuronal excitation (fewer Fos-related antigen-like-immunoreactive neurons), lower plasma norepinephrine levels, and improved peripheral manifestations of HF compared with HF rats treated with control siRNAs. These results demonstrate that ERK1/2 signaling in the PVN plays a pivotal role in mediating sympathetic drive in HF induced by myocardial infarction and may be a novel target for therapeutic intervention.
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Affiliation(s)
- Yang Yu
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Shun-Guang Wei
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Zhi-Hua Zhang
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Robert M Weiss
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Robert B Felder
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
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Wei SG, Yu Y, Weiss RM, Felder RB. Inhibition of Brain Mitogen-Activated Protein Kinase Signaling Reduces Central Endoplasmic Reticulum Stress and Inflammation and Sympathetic Nerve Activity in Heart Failure Rats. Hypertension 2015; 67:229-36. [PMID: 26573710 DOI: 10.1161/hypertensionaha.115.06329] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 10/24/2015] [Indexed: 01/05/2023]
Abstract
Mitogen-activated protein kinase (MAPK) signaling and endoplasmic reticulum (ER) stress in the brain have been implicated in the pathophysiology of hypertension. This study determined whether ER stress occurs in subfornical organ and hypothalamic paraventricular nucleus in heart failure (HF) and how MAPK signaling interacts with ER stress and other inflammatory mediators. HF rats had significantly higher levels of the ER stress biomarkers (glucose-regulated protein 78, activating transcription factor 6, activating transcription factor 4, X-box binding protein 1, P58(IPK), and C/EBP homologous protein) in subfornical organ and paraventricular nucleus, which were attenuated by a 4-week intracerebroventricular infusion of inhibitors selective for p44/42 MAPK (PD98059), p38 MAPK (SB203580), or c-Jun N-terminal kinase (SP600125). HF rats also had higher mRNA levels of tumor necrosis factor-α, interleukin-1β, cyclooxygenase-2, and nuclear factor-κB p65, and a lower mRNA level of IκB-α, in subfornical organ and paraventricular nucleus, compared with SHAM rats, and these indicators of increased inflammation were attenuated in the HF rats treated with the MAPK inhibitors. Plasma norepinephrine level was higher in HF rats than in SHAM rats but was reduced in the HF rats treated with PD98059 and SB203580. A 4-week intracerebroventricular infusion of PD98059 also improved some hemodynamic and anatomic indicators of left ventricular function in HF rats. These data demonstrate that ER stress increases in the subfornical organ and paraventricular nucleus of rats with ischemia-induced HF and that inhibition of brain MAPK signaling reduces brain ER stress and inflammation and decreases sympathetic excitation in HF. An interaction between MAPK signaling and ER stress in cardiovascular regions of the brain may contribute to the development of HF.
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Affiliation(s)
- Shun-Guang Wei
- From the Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City (S.-G.W., Y.Y., R.M.W., R.B.F.); and Research Service, Veterans Affairs Medical Center, Iowa City, IA (R.B.F.)
| | - Yang Yu
- From the Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City (S.-G.W., Y.Y., R.M.W., R.B.F.); and Research Service, Veterans Affairs Medical Center, Iowa City, IA (R.B.F.)
| | - Robert M Weiss
- From the Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City (S.-G.W., Y.Y., R.M.W., R.B.F.); and Research Service, Veterans Affairs Medical Center, Iowa City, IA (R.B.F.)
| | - Robert B Felder
- From the Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City (S.-G.W., Y.Y., R.M.W., R.B.F.); and Research Service, Veterans Affairs Medical Center, Iowa City, IA (R.B.F.).
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Lincevicius GS, Shimoura CG, Nishi EE, Perry JC, Casarini DE, Gomes GN, Bergamaschi CT, Campos RR. Aldosterone Contributes to Sympathoexcitation in Renovascular Hypertension. Am J Hypertens 2015; 28:1083-90. [PMID: 25628418 DOI: 10.1093/ajh/hpu300] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 12/18/2014] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Although angiotensin II (Ang II) is essential to the development of renovascular hypertension, aldosterone plays a role as well. Recent studies have demonstrated a cross-talk between Ang II type 1 and mineralocorticoid receptors in the brain and kidneys. However, the role of aldosterone in the autonomic and renal dysfunction of renovascular hypertension is not well understood. AIM The current study evaluated whether aldosterone contributes to cardiovascular and renal dysfunction in the 2 kidney-1 clip (2K1C) model. METHODS Mean arterial pressure (MAP) and baroreceptor reflex for control of the heart rate were evaluated in 2K1C treated or not treated with spironolactone (200mg/kg/day, 7 days). Tonic and reflex control of renal sympathetic nerve activity (rSNA) were assessed in urethane-anaesthetized rats. Plasma renin activity (PRA), kidney renin protein expression, renal injury, and central AT1 receptor protein expression were assessed. RESULTS Spiro reduced MAP (198±4 vs. 170±9mm Hg; P < 0.05), normalized rSNA (147±9 vs. 96±10 pps; P < 0.05), and increased renal baroreceptor reflex sensitivity in the 2K1C rats. Spiro reduced α-smooth muscle actin expression in the nonclipped kidney in the 2K1C group (5±0.6 vs. 1.1±0.2%; P < 0.05). There was no change in PRA; however, a decrease in renin protein expression in the nonclipped kidney was found in the 2K1C treated group (217±30 vs. 160±19%; P < 0.05). Spiro treatment decreased AT1 receptor in the central nervous system (CNS) only in 2K1C rats (138±10 vs. 84±12%; P < 0.05). CONCLUSION Aldosterone contributes to autonomic dysfunction and intrarenal injury in 2K1C, these effects are mediated by the CNS.
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Affiliation(s)
- Gisele S Lincevicius
- Department of Physiology - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Caroline G Shimoura
- Department of Physiology - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Erika E Nishi
- Department of Physiology - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Juliana C Perry
- Department of Psychobiology - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Dulce E Casarini
- Nephrology Division, Department of Medicine - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Guiomar N Gomes
- Department of Physiology - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Cássia T Bergamaschi
- Department of Physiology - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Ruy R Campos
- Department of Physiology - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil;
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Drummond HA. Nontubular epithelial Na+ channel proteins in cardiovascular regulation. Physiol Rep 2015; 3:3/5/e12404. [PMID: 25991722 PMCID: PMC4463832 DOI: 10.14814/phy2.12404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Heather A Drummond
- Department of Physiology and Biophysics, University of Mississippi Medical, Jackson, Mississippi, USA
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Gomez-Sanchez EP. Brain mineralocorticoid receptors in cognition and cardiovascular homeostasis. Steroids 2014; 91:20-31. [PMID: 25173821 PMCID: PMC4302001 DOI: 10.1016/j.steroids.2014.08.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 07/10/2014] [Accepted: 08/04/2014] [Indexed: 12/20/2022]
Abstract
Mineralocorticoid receptors (MR) mediate diverse functions supporting osmotic and hemodynamic homeostasis, response to injury and inflammation, and neuronal changes required for learning and memory. Inappropriate MR activation in kidneys, heart, vessels, and brain hemodynamic control centers results in cardiovascular and renal pathology and hypertension. MR binds aldosterone, cortisol and corticosterone with similar affinity, while the glucocorticoid receptor (GR) has less affinity for cortisol and corticosterone. As glucocorticoids are more abundant than aldosterone, aldosterone activates MR in cells co-expressing enzymes with 11β-hydroxydehydrogenase activity to inactivate them. MR and GR co-expressed in the same cell interact at the molecular and functional level and these functions may be complementary or opposing depending on the cell type. Thus the balance between MR and GR expression and activation is crucial for normal function. Where 11β-hydroxydehydrogenase 2 (11β-HSD2) that inactivates cortisol and corticosterone in aldosterone target cells of the kidney and nucleus tractus solitarius (NTS) is not expressed, as in most neurons, MR are activated at basal glucocorticoid concentrations, GR at stress concentrations. An exception may be pre-autonomic neurons of the PVN which express MR and 11β-HSD1 in the absence of hexose-6-phosphate dehydrogenase required to generate the requisite cofactor for reductase activity, thus it acts as a dehydrogenase. MR antagonists, valuable adjuncts to the treatment of cardiovascular disease, also inhibit MR in the brain that are crucial for memory formation and exacerbate detrimental effects of excessive GR activation on cognition and mood. 11β-HSD1 inhibitors combat metabolic and cognitive diseases related to glucocorticoid excess, but may exacerbate MR action where 11β-HSD1 acts as a dehydrogenase, while non-selective 11β-HSD1&2 inhibitors cause injurious disruption of MR hemodynamic control. MR functions in the brain are multifaceted and optimal MR:GR activity is crucial. Therefore selectively targeting down-stream effectors of MR specific actions may be a better therapeutic goal.
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Affiliation(s)
- Elise P Gomez-Sanchez
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS 39216, USA.
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Rafatian N, Westcott KV, White RA, Leenen FHH. Cardiac macrophages and apoptosis after myocardial infarction: effects of central MR blockade. Am J Physiol Regul Integr Comp Physiol 2014; 307:R879-87. [PMID: 25100076 DOI: 10.1152/ajpregu.00075.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
After myocardial infarction (post-MI), inflammation and apoptosis contribute to progressive cardiac remodeling and dysfunction. Cardiac mineralocorticoid receptor (MR) and β-adrenergic signaling promote apoptosis and inflammation. Post-MI, MR activation in the brain contributes to sympathetic hyperactivity and an increase in cardiac aldosterone. In the present study, we assessed the time course of macrophage infiltration and apoptosis in the heart as detected by both terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and active caspase-3 immunostaining in both myocytes and nonmyocytes, as well as the effects of central MR blockade by intracerebroventricular infusion of eplerenone at 5 μg/day on peak changes in macrophage infiltration and apoptosis post-MI. Macrophage numbers were markedly increased in the infarct and peri-infarct zones and to a minor extent in the noninfarct part of the left ventricle at 10 days post-MI and decreased over the 3-mo study period. Apoptosis of both myocytes and nonmyocytes was clearly apparent in the infarct and peri-infarct areas at 10 days post-MI. For TUNEL, the increases persisted at 4 and 12 wk, but the number of active caspase-3-positive cells markedly decreased. Central MR blockade significantly decreased CD80-positive proinflammatory M1 macrophages and increased CD163-positive anti-inflammatory M2 macrophages in the infarct. Central MR blockade also reduced apoptosis of myocytes by 40-50% in the peri-infarct and to a lesser extent of nonmyocytes in the peri-infarct and infarct zones. These findings indicate that MR activation in the brain enhances apoptosis both in myocytes and nonmyocytes in the peri-infarct and infarct area post-MI and contributes to the inflammatory response.
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Affiliation(s)
- Naimeh Rafatian
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Katherine V Westcott
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Roselyn A White
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and
| | - Frans H H Leenen
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
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Abstract
The primary adrenal cortical steroid hormones, aldosterone, and the glucocorticoids cortisol and corticosterone, act through the structurally similar mineralocorticoid (MR) and glucocorticoid receptors (GRs). Aldosterone is crucial for fluid, electrolyte, and hemodynamic homeostasis and tissue repair; the significantly more abundant glucocorticoids are indispensable for energy homeostasis, appropriate responses to stress, and limiting inflammation. Steroid receptors initiate gene transcription for proteins that effect their actions as well as rapid non-genomic effects through classical cell signaling pathways. GR and MR are expressed in many tissues types, often in the same cells, where they interact at molecular and functional levels, at times in synergy, others in opposition. Thus the appropriate balance of MR and GR activation is crucial for homeostasis. MR has the same binding affinity for aldosterone, cortisol, and corticosterone. Glucocorticoids activate MR in most tissues at basal levels and GR at stress levels. Inactivation of cortisol and corticosterone by 11β-HSD2 allows aldosterone to activate MR within aldosterone target cells and limits activation of the GR. Under most conditions, 11β-HSD1 acts as a reductase and activates cortisol/corticosterone, amplifying circulating levels. 11β-HSD1 and MR antagonists mitigate inappropriate activation of MR under conditions of oxidative stress that contributes to the pathophysiology of the cardiometabolic syndrome; however, MR antagonists decrease normal MR/GR functional interactions, a particular concern for neurons mediating cognition, memory, and affect.
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Affiliation(s)
- Elise Gomez-Sanchez
- G.V.(Sonny) Montgomery V.A. Medical Center and Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi
| | - Celso E. Gomez-Sanchez
- G.V.(Sonny) Montgomery V.A. Medical Center and Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi
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12
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Drobysheva A, Ahmad M, White R, Wang HW, Leenen FHH. Cardiac sympathetic innervation and PGP9.5 expression by cardiomyocytes after myocardial infarction: effects of central MR blockade. Am J Physiol Heart Circ Physiol 2013; 305:H1817-29. [DOI: 10.1152/ajpheart.00445.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Central mechanisms involving mineralocorticoid receptor (MR) activation contribute to an increase in sympathetic tone after myocardial infarction (MI). We hypothesized that this central mechanism also contributes to cardiac sympathetic axonal sprouting and that central MR blockade reduces cardiac sympathetic hyperinnervation post-MI. Post-MI, tyrosine hydroxylase (TH) and norepinephrine transporter protein content in the noninfarcted base of the heart remained unaltered. In contrast, protein gene product (PGP)9.5 protein was increased twofold in the base of the heart and sixfold in the peri-infarct area at 1 wk post-MI and was associated with increased ubiquitin expression. These changes persisted to a lesser extent at 4 wk post-MI and were no longer present at 12 wk. Cardiac myocytes rather than sympathetic axons were the main source of this elevated PGP9.5 expression. At 7–10 days post-MI, in the peri-infarct area, sympathetic hyperinnervation was observed with a fourfold increase in growth-associated protein 43, a twofold increase in TH, and a 50% increase in PGP9.5-positive fibers compared with the epicardial side of the left ventricle in sham rats. Central infusion of the MR blocker eplerenone markedly attenuated these increases in nerve densities but did not affect overall cardiac PGP9.5 and ubiquitin protein overexpression. We conclude that central MR activation contributes to sympathetic hyperinnervation, possibly by decreasing cardiac sympathetic activity post-MI, or by affecting other mechanisms, such as the expression of nerve growth factor. Marked PGP9.5 expression occurs in cardiomyocytes early post-MI, which may contribute to the increase in ubiquitin.
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Affiliation(s)
- Anastasia Drobysheva
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Monir Ahmad
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Roselyn White
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Hong-Wei Wang
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Frans H. H. Leenen
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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13
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van den Berg TNA, Rongen GA, Fröhlich GM, Deinum J, Hausenloy DJ, Riksen NP. The cardioprotective effects of mineralocorticoid receptor antagonists. Pharmacol Ther 2013; 142:72-87. [PMID: 24275323 DOI: 10.1016/j.pharmthera.2013.11.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 11/04/2013] [Indexed: 01/14/2023]
Abstract
Despite state-of-the-art reperfusion therapy, morbidity and mortality remain significant in patients with an acute myocardial infarction. Therefore, novel strategies to limit myocardial ischemia-reperfusion injury are urgently needed. Mineralocorticoid receptor (MR) antagonists are attractive candidates for this purpose, since several clinical trials in patients with heart failure have reported a survival benefit with MR antagonist treatment. MRs are expressed by several cells of the cardiovascular system, including cardiomyocytes, cardiac fibroblasts, vascular smooth muscle cells, and endothelial cells. Experiments in animal models of myocardial infarction have demonstrated that acute administration of MR antagonists, either before ischemia or immediately at the moment of coronary reperfusion, limits infarct size. This action appears to be independent of the presence of aldosterone and cortisol, which are the endogenous ligands for the MR. The cardioprotective effect is mediated by a nongenomic intracellular signaling pathway, including adenosine receptor stimulation, and activation of several components of the Reperfusion Injury Salvage Kinase (RISK) pathway. In addition to limiting infarct size, MR antagonists can improve scar healing when administered shortly after reperfusion and can reduce cardiac remodeling post myocardial infarction. Clinical trials are currently being performed studying whether early administration of MR antagonists can indeed improve prognosis in patients with an acute myocardial infarction, independent of the presence of heart failure.
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Affiliation(s)
- T N A van den Berg
- Department of Pharmacology and Toxicology, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of General Internal Medicine, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Gerard A Rongen
- Department of Pharmacology and Toxicology, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of General Internal Medicine, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Georg M Fröhlich
- The Hatter Cardiovascular Institute, University College London, United Kingdom
| | - Jaap Deinum
- Department of General Internal Medicine, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Derek J Hausenloy
- The Hatter Cardiovascular Institute, University College London, United Kingdom
| | - Niels P Riksen
- Department of Pharmacology and Toxicology, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of General Internal Medicine, Radboud University Medical Centre, Nijmegen, the Netherlands.
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Ogawa K, Hirooka Y, Kishi T, Ide T, Sunagawa K. Partially silencing brain toll-like receptor 4 prevents in part left ventricular remodeling with sympathoinhibition in rats with myocardial infarction-induced heart failure. PLoS One 2013; 8:e69053. [PMID: 23874864 PMCID: PMC3706428 DOI: 10.1371/journal.pone.0069053] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Accepted: 06/04/2013] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Left ventricular (LV) remodeling and activation of sympathetic nervous system (SNS) are cardinal features of heart failure. We previously demonstrated that enhanced central sympathetic outflow is associated with brain toll-like receptor 4 (TLR4) probably mediated by brain angiotensin II type 1 receptor in mice with myocardial infarction (MI)-induced heart failure. The purpose of the present study was to examine whether silencing brain TLR4 could prevent LV remodeling with sympathoinhibition in MI-induced heart failure. METHODOLOGY/PRINCIPAL FINDINGS MI-induced heart failure model rats were created by ligation of left coronary artery. The expression level of TLR4 in brainstem was significantly higher in MI-induced heart failure treated with intracerebroventricular (ICV) injection of hGAPDH-SiRNA than in sham. TLR4 in brainstem was significantly lower in MI-induced heart failure treated with ICV injection of TLR4-SiRNA than in that treated with ICV injection of hGAPDH-SiRNA. Lung weight, urinary norepinephrine excretion, and LV end-diastolic pressure were significantly lower and LV dimension was significantly smaller in MI-induced heart failure treated with TLR4-SiRNA than in that treated with hGAPDH-SiRNA for 2 weeks. CONCLUSIONS Partially silencing brain TLR4 by ICV injection of TLR4-SiRNA for 2 weeks could in part prevent LV remodeling with sympathoinhibition in rats with MI-induced heart failure. Brain TLR4 has a potential to be a target of the treatment for MI-induced heart failure.
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Affiliation(s)
- Kiyohiro Ogawa
- Departments of Cardiovascular Medicine, Kyushu University Graduate School of Medical Science, Fukuoka, Japan
| | - Yoshitaka Hirooka
- Advanced Cardiovascular Regulation and Therapeutics, Kyushu University Graduate School of Medical Science, Fukuoka, Japan
- * E-mail:
| | - Takuya Kishi
- Advanced Therapeutics for Cardiovascular Diseases, Kyushu University Graduate School of Medical Science, Fukuoka, Japan
| | - Tomomi Ide
- Departments of Cardiovascular Medicine, Kyushu University Graduate School of Medical Science, Fukuoka, Japan
| | - Kenji Sunagawa
- Departments of Cardiovascular Medicine, Kyushu University Graduate School of Medical Science, Fukuoka, Japan
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Do high doses of AT(1)-receptor blockers attenuate central sympathetic outflow in humans with chronic heart failure? Clin Sci (Lond) 2013; 124:589-95. [PMID: 23163825 DOI: 10.1042/cs20120437] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In patients with CHF (chronic heart failure) sympathetic activity increases as cardiac performance decreases and filling pressures increase. We hypothesized that in patients with mild-to-moderate CHF, higher than conventional doses of an AT1-receptor [AngII (angiotensin II) type 1 receptor] antagonist would achieve greater central AT1-receptor blockade, resulting in diminished MSNA (muscle sympathetic nerve activity) and augmented MSNA variability, two indices of central effects on sympathetic outflow. In total, 13 patients with ischaemic cardiomyopathy [NYHA (New York Heart Association) class II-III] were weaned off all pharmacological RAS (renin-angiotensin system) modifiers, and then randomized to receive a low (50 mg/day) or high (200 mg/day) dose of losartan. Central haemodynamics, MSNA and its variability, plasma catecholamines, AngI (angiotensin I) and AngII and aldosterone were assessed both before and 3 months after randomization. Neither dose altered BP (blood pressure), PCWP (pulmonary capillary wedge pressure) or CI (cardiac index) significantly. Compared with 50 mg daily, losartan 200 mg/day decreased MSNA significantly (P<0.05), by approximately 15 bursts/min, and increased MSNA variability within the 0.27-0.33 Hz high-frequency range by 0.11 units(2)/Hz (P=0.06). PNE [plasma noradrenaline (norepinephrine)] fell in parallel with changes in MSNA (r=0.62; P<0.05). These findings support the hypothesis that higher than conventional doses of lipophilic ARBs (AT1-receptor blockers) can modulate the intensity and variability of central sympathetic outflow in patients with CHF. The efficacy and safety of this conceptual change in the therapeutic approach to heart failure merits prospective testing in clinical trials.
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Activation of mineralocorticoid receptors in the rostral ventrolateral medulla is involved in hypertensive mechanisms in stroke-prone spontaneously hypertensive rats. Hypertens Res 2012; 35:470-6. [DOI: 10.1038/hr.2011.220] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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17
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Zhang ZH, Yu Y, Wei SG, Felder RB. Aldosterone-induced brain MAPK signaling and sympathetic excitation are angiotensin II type-1 receptor dependent. Am J Physiol Heart Circ Physiol 2011; 302:H742-51. [PMID: 22081704 DOI: 10.1152/ajpheart.00856.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Angiotensin II (ANG II)-induced mitogen-activated protein kinase (MAPK) signaling upregulates angiotensin II type-1 receptors (AT(1)R) in hypothalamic paraventricular nucleus (PVN) and contributes to AT(1)R-mediated sympathetic excitation in heart failure. Aldosterone has similar effects to increase AT(1)R expression in the PVN and sympathetic drive. The present study was undertaken to determine whether aldosterone also activates the sympathetic nervous system via MAPK signaling and, if so, whether its effect is independent of ANG II and AT(1)R. In anesthetized rats, a 4-h intravenous infusion of aldosterone induced increases (P < 0.05) in phosphorylated (p-) p44/42 MAPK in PVN, PVN neuronal excitation, renal sympathetic nerve activity (RSNA), mean blood pressure (MBP), and heart rate (HR). Intracerebroventricular or bilateral PVN microinjection of the p44/42 MAPK inhibitor PD-98059 reduced the aldosterone-induced RSNA, HR, and MBP responses. Intracerebroventricular pretreatment (5 days earlier) with pooled small interfering RNAs targeting p44/42 MAPK reduced total and p-p44/42 MAPK, aldosterone-induced c-Fos expression in the PVN, and the aldosterone-induced increases in RSNA, HR, and MBP. Intracerebroventricular infusion of either the mineralocorticoid receptor antagonist RU-28318 or the AT(1)R antagonist losartan blocked aldosterone-induced phosphorylation of p44/42 MAPK and prevented the increases in RSNA, HR, and MBP. These data suggest that aldosterone-induced sympathetic excitation depends upon that AT(1)R-induced MAPK signaling in the brain. The short time course of this interaction suggests a nongenomic mechanism, perhaps via an aldosterone-induced transactivation of the AT(1)R as described in peripheral tissues.
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Affiliation(s)
- Zhi-Hua Zhang
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, owa City, IA52242, USA.
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Takahashi H, Yoshika M, Komiyama Y, Nishimura M. The central mechanism underlying hypertension: a review of the roles of sodium ions, epithelial sodium channels, the renin-angiotensin-aldosterone system, oxidative stress and endogenous digitalis in the brain. Hypertens Res 2011; 34:1147-60. [PMID: 21814209 PMCID: PMC3324327 DOI: 10.1038/hr.2011.105] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 05/08/2011] [Accepted: 05/15/2011] [Indexed: 02/07/2023]
Abstract
The central nervous system has a key role in regulating the circulatory system by modulating the sympathetic and parasympathetic nervous systems, pituitary hormone release, and the baroreceptor reflex. Digoxin- and ouabain-like immunoreactive materials were found >20 years ago in the hypothalamic nuclei. These factors appeared to localize to the paraventricular and supraoptic nuclei and the nerve fibers at the circumventricular organs and supposed to affect electrolyte balance and blood pressure. The turnover rate of these materials increases with increasing sodium intake. As intracerebroventricular injection of ouabain increases blood pressure via sympathetic activation, an endogenous digitalis-like factor (EDLF) was thought to regulate cardiovascular system-related functions in the brain, particularly after sodium loading. Experiments conducted mainly in rats revealed that the mechanism of action of ouabain in the brain involves sodium ions, epithelial sodium channels (ENaCs) and the renin-angiotensin-aldosterone system (RAAS), all of which are affected by sodium loading. Rats fed a high-sodium diet develop elevated sodium levels in their cerebrospinal fluid, which activates ENaCs. Activated ENaCs and/or increased intracellular sodium in neurons activate the RAAS; this releases EDLF in the brain, activating the sympathetic nervous system. The RAAS promotes oxidative stress in the brain, further activating the RAAS and augmenting sympathetic outflow. Angiotensin II and aldosterone of peripheral origin act in the brain to activate this cascade, increasing sympathetic outflow and leading to hypertension. Thus, the brain Na(+)-ENaC-RAAS-EDLF axis activates sympathetic outflow and has a crucial role in essential and secondary hypertension. This report provides an overview of the central mechanism underlying hypertension and discusses the use of antihypertensive agents.
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Affiliation(s)
- Hakuo Takahashi
- Department of Clinical Sciences and Laboratory Medicine, Kansai Medical University, Hirakata City, Osaka, Japan.
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19
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Huang BS, Zheng H, Tan J, Patel KP, Leenen FHH. Regulation of hypothalamic renin-angiotensin system and oxidative stress by aldosterone. Exp Physiol 2011; 96:1028-38. [PMID: 21824999 DOI: 10.1113/expphysiol.2011.059840] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In rats with salt-induced hypertension or postmyocardial infarction, angiotensin II type 1 receptor (AT(1)R) densities and oxidative stress increase and neuronal NO synthase (nNOS) levels decrease in the paraventricular nucleus (PVN). The present study was designed to determine whether these changes may depend on activation of the aldosterone -'ouabain' neuromodulatory pathway. After intracerebroventricular (i.c.v.) infusion of aldosterone (20 ng h(-1)) for 14 days, blood pressure (BP) and heart rate (HR) were recorded in conscious Wistar rats, and mRNA and protein for nNOS, endothelial NO synthase (eNOS), AT(1)R and NADPH oxidase subunits were assessed in brain tissue. Blood pressure and HR were significantly increased by aldosterone. Aldosterone significantly increased mRNA and protein of AT(1)R, P22phox, P47phox, P67phox and Nox2, and decreased nNOS but not eNOS mRNA and protein in the PVN, as well as increased the angiotensin-converting enzyme and AT(1)R binding densities in the PVN and supraoptic nucleus. The increases in BP and HR, as well as the changes in mRNA, proteins and angiotensin-converting enzyme and AT(1)R binding densities were all largely prevented by concomitant i.c.v. infusion of Digibind (to bind 'ouabain') or benzamil (to block presumed epithelial sodium channels). These data indicate that aldosterone, via 'ouabain', increases in the PVN angiotensin-converting enzyme, AT(1)R and oxidative stress, but decreases nNOS, and suggest that endogenous aldosterone may cause the similar pattern of changes observed in salt-sensitive hypertension and heart failure postmyocardial infarction.
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Affiliation(s)
- Bing S Huang
- University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario, Canada K1Y 4W7
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20
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Albaghdadi M, Gheorghiade M, Pitt B. Mineralocorticoid receptor antagonism: therapeutic potential in acute heart failure syndromes. Eur Heart J 2011; 32:2626-33. [DOI: 10.1093/eurheartj/ehr170] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
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Heshka J, Ruzicka M, Hiremath S, McCormick BB. Spironolactone for difficult to control hypertension in chronic kidney disease: an analysis of safety and efficacy. ACTA ACUST UNITED AC 2011; 4:295-301. [PMID: 21130976 DOI: 10.1016/j.jash.2010.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 09/09/2010] [Accepted: 09/28/2010] [Indexed: 01/01/2023]
Abstract
Spironolactone is effective at treating difficult to control hypertension in the general population, and it is unknown if it is safe or effective for those with chronic kidney disease (CKD) and difficult-to-control hypertension. In a retrospective cohort design, 88 patients with difficult-to-control hypertension study were assessed for blood pressure (BP) response to spironolactone as well as for biochemical changes. In the CKD group (34 patients), the average systolic BP (SBP) fell from 153 ± 18 to 143 ± 20 mm Hg (P = .006) compared with a fall in SBP from 150 ± 17 to 135 ± 17 mm Hg (P < .0001) in the non-CKD group (P < .0001). In 44% of those with CKD and 59% of those without CKD, SBP decreased by >10 mm Hg (defined as responders; P = .22). Potassium rose by 0.5 ± 0.6 mmol/L in the CKD group and 0.3 ± 0.5 mmol/L in the non-CKD group (P = .12). The overall incidence of hyperkalemia was 5.7% in the CKD group and 0% in the non-CKD group (P = .07). Spironolactone is associated with a significant fall in BP among those with CKD and difficult-to-control BP. It is associated with a modest rise in serum potassium, which is more pronounced among those with glomerular filtration rate below 45 mL/minute.
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Affiliation(s)
- Jodi Heshka
- Department of Medicine, University of Ottawa, Ottawa, Ontario
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22
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Blockade of mineralocorticoid receptors improves salt-induced left-ventricular systolic dysfunction through attenuation of enhanced sympathetic drive in mice with pressure overload. J Hypertens 2010; 28:1449-58. [PMID: 20589973 DOI: 10.1097/hjh.0b013e328338bb37] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES In a pressure overload model, sympathetic activity is augmented in response to salt intake. Mineralocorticoid receptors and epithelial Na channels (ENaCs) are thought to contribute to Na-processing, but the underlying mechanism is unknown. Here, we investigated the contribution of the brain mineralocorticoid receptor- ENaC pathway to salt-induced sympathetic activation in a pressure overload model. METHODS AND RESULTS Aortic banding was performed to produce a mouse pressure overload model. Four weeks after aortic banding (AB-4), left-ventricular (LV) wall thickness was increased without a change in percentage fractional shortening (%FS). Sympathetic activity increased in response to a 5-day high-salt diet in AB-4, but not in Sham-4. Brain mineralocorticoid receptor, alphaENaC, and angiotensin II type 1 receptor (AT1R) expression levels were greater in AB-4 than in Sham-4. The increase in sympathetic activity and in the expression of these proteins was blocked by intracerebroventricular (ICV) infusion of eplerenone, a mineralocorticoid receptor blocker. In another protocol, AB-4 mice were fed a high-salt diet (AB-H) for 4 additional weeks. At 4 weeks, %FS was decreased and sympathetic activity was increased in AB-H compared with Sham. Expression of mineralocorticoid receptors and AT1R in the brain was higher in AB-H than in Sham. ICV infusion of eplerenone in AB-H attenuated salt-induced sympathoexcitation and the decreased %FS. ICV infusion of eplerenone also decreased brain AT1R expression. CONCLUSIONS These findings indicate that activation of brain alphaENaC and AT1R through mineralocorticoid receptors contributes to the acquisition of Na sensitivity to induce sympathoexcitation. Therefore, high salt intake accelerates sympathetic activation and LV systolic dysfunction in a pressure overload model.
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Abrams JM, Engeland WC, Osborn JW. Effect of intracerebroventricular benzamil on cardiovascular and central autonomic responses to DOCA-salt treatment. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1500-10. [PMID: 20926762 DOI: 10.1152/ajpregu.00431.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
DOCA-salt treatment increases mean arterial pressure (MAP), while central infusion of benzamil attenuates this effect. The present study used c-Fos immunoreactivity to assess the role of benzamil-sensitive proteins in the brain on neural activity following chronic DOCA-salt treatment. Uninephrectomized rats were instrumented with telemetry transmitters for measurement of MAP and with an intracerebroventricular (ICV) cannula for benzamil administration. Groups included rats receiving DOCA-salt treatment alone, rats receiving DOCA-salt treatment with ICV benzamil, and appropriate controls. At study completion, MAP in vehicle-treated DOCA-salt rats reached 142 ± 4 mmHg. In contrast DOCA-salt rats receiving ICV benzamil had lower MAP (124 ± 3 mmHg). MAP in normotensive controls was 102 ± 3 mmHg. c-Fos immunoreactivity was quantified in the supraoptic nucleus (SON) and across subnuclei of the hypothalamic paraventricular nucleus (PVN), as well as other cardiovascular regulatory sites. Compared with vehicle-treated normotensive controls, c-Fos expression was increased in the SON and all subnuclei of the PVN, but not in other key autonomic nuclei, such as the rostroventrolateral medulla. Moreover, benzamil treatment decreased c-Fos immunoreactivity in the SON and in medial parvocellular and posterior magnocellular neurons of the PVN in DOCA-salt rats but not areas associated with regulation of sympathetic activity. Our results do not support the hypothesis that DOCA-salt increases neuronal activity (as indicated by c-Fos immunoreactivity) of other key regions that regulate sympathetic activity. These results suggest that ICV benzamil attenuates DOCA-salt hypertension by modulation of neuroendocrine-related PVN nuclei rather than inhibition of PVN sympathetic premotor neurons in the PVN and rostroventrolateral medulla.
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Affiliation(s)
- Joanna M Abrams
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
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Huang BS, Ahmadi S, Ahmad M, White RA, Leenen FHH. Central neuronal activation and pressor responses induced by circulating ANG II: role of the brain aldosterone-“ouabain” pathway. Am J Physiol Heart Circ Physiol 2010; 299:H422-30. [DOI: 10.1152/ajpheart.00256.2010] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An increase in plasma ANG II causes neuronal activation in hypothalamic nuclei and a slow pressor response, presumably by increasing sympathetic drive. We evaluated whether the activation of a neuromodulatory pathway, involving aldosterone and “ouabain,” is involved in these responses. In Wistar rats, the subcutaneous infusion of ANG II at 150 and 500 ng·kg−1·min−1 gradually increased blood pressure up to 60 mmHg at the highest dose. ANG II at 500 ng·kg−1·min−1 increased plasma ANG II by 4-fold, plasma aldosterone by 25-fold, and hypothalamic aldosterone by 3-fold. The intracerebroventricular infusion of an aldosterone synthase (AS) inhibitor prevented the ANG II-induced increase in hypothalamic aldosterone without affecting the increase in plasma aldosterone. Neuronal activity, as assessed by Fra-like immunoreactivity, increased transiently in the subfornical organ (SFO) but progressively in the paraventricular nucleus (PVN) and supraoptic nucleus (SON). The central infusion of the AS inhibitor or a mineralocorticoid receptor blocker markedly attenuated the ANG II-induced neuronal activation in the PVN but not in the SON. Pressor responses to ANG II at 150 ng·kg−1·min−1 were abolished by an intracerebroventricular infusion of the AS inhibitor. Pressor responses to ANG II at 500 ng·kg−1·min−1 were attenuated by the central infusion of the AS inhibitor or the mineralocorticoid receptor blocker by 70–80% and by Digibind (to bind “ouabain”) by 50%. These results suggest a novel central nervous system mechanism for the ANG II-induced slow pressor response, i.e., circulating ANG II activates the SFO, leading to the direct activation of the PVN and SON, and, in addition, via aldosterone-dependent amplifying mechanisms, causes sustained activation of the PVN and thereby hypertension.
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Affiliation(s)
- Bing S. Huang
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Sara Ahmadi
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Monir Ahmad
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Roselyn A. White
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Frans H. H. Leenen
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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Wray DW, Supiano MA. Impact of aldosterone receptor blockade compared with thiazide therapy on sympathetic nervous system function in geriatric hypertension. Hypertension 2010; 55:1217-23. [PMID: 20368505 DOI: 10.1161/hypertensionaha.109.147058] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Aldosterone receptor blockade and thiazide therapy effectively lower blood pressure in geriatric hypertension. Their impact on sympathetic nervous system function has not been evaluated. In a double-blind, randomized study, 36 patients with stage 1 hypertension underwent 6 months of therapy with either aldosterone receptor blockade (spironolactone, n=19; 68+/-1 years) or hydrochlorothiazide (n=17; 68+/-2 years). Arterial blood pressure, [(3)H]-norepinephrine (NE) kinetics (extravascular NE release rate), and alpha-adrenergic responsiveness (forearm vasoconstriction to graded intrabrachial artery NE infusions) were evaluated at baseline, after a 4-week antihypertensive medication withdrawal, and after spironolactone or hydrochlorothiazide treatment. Arterial blood pressure decreased significantly with both spironolactone (160+/-3 to 134+/-2 mm Hg; 77+/-2 to 68+/-2 mm Hg) and hydrochlorothiazide (161+/-4 to 145+/-4 mm Hg; 78+/-2 to 73+/-2 mm Hg) treatment. Sympathetic nervous system activity was significantly reduced after spironolactone (plasma NE: 378+/-40 to 335+/-20 pg/mL, P=0.04; [(3)H]-NE release rate: 2.74+/-0.3 to 1.97+/-0.2 microg/min per meter squared, P=0.04) but not hydrochlorothiazide (plasma NE: 368+/-25 to 349+/-23 pg/mL, P=0.47; [(3)H]-NE release rate: 2.63+/-0.4 to 2.11+/-0.2 mg/min per meter squared, P=0.21). alpha-Adrenergic responsiveness was unchanged with either drug treatment. These findings demonstrate a beneficial effect of aldosterone receptor blockade on reducing sympathetic nervous system activity and blood pressure in hypertensive older patients.
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Affiliation(s)
- D Walter Wray
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT 84132, USA.
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The Renin-Angiotensin System in the Development of Salt-Sensitive Hypertension in Animal Models and Humans. Pharmaceuticals (Basel) 2010; 3:940-960. [PMID: 27713283 PMCID: PMC4034015 DOI: 10.3390/ph3040940] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 02/25/2010] [Accepted: 03/08/2010] [Indexed: 02/07/2023] Open
Abstract
Hypertension is still one of the major causes of death from cardiovascular failure. Increased salt intake may aggravate the rise in blood pressure and the development of consequential damage of the heart, the vessels and other organs. The general necessity of restricted salt intake regardless of blood pressure or salt sensitivity has been a matter of debate over the past decades. This review summarizes the main pathogenic mechanisms of hypertension and salt sensitivity in rat models, particularly in the spontaneously hypertensive rat (SHR), and in patients with essential hypertension (EH). Although SHRs are commonly considered to be salt-resistant, there is much evidence that salt loading may deteriorate blood pressure and cardiovascular function even in these animals. Similarly, EH is not a homogenous disorder - some patients, but not all, exhibit pronounced salt sensitivity. The renin-angiotensin system (RAS) plays a key role in the regulation of blood pressure and salt and fluid homeostasis and thus is one of the main targets of antihypertensive therapy. This review focuses on the contribution of the RAS to the pathogenesis of salt-sensitive hypertension in SHRs and patients with EH.
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Yu Y, Zhang ZH, Wei SG, Serrats J, Weiss RM, Felder RB. Brain perivascular macrophages and the sympathetic response to inflammation in rats after myocardial infarction. Hypertension 2010; 55:652-9. [PMID: 20142564 DOI: 10.1161/hypertensionaha.109.142836] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Inflammation is associated with increased sympathetic drive in cardiovascular diseases. Blood-borne proinflammatory cytokines, markers of inflammation, induce cyclooxygenase 2 (COX-2) activity in perivascular macrophages of the blood-brain barrier. COX-2 generates prostaglandin E(2), which may enter the brain and increase sympathetic nerve activity. We examined the contribution of this mechanism to augmented sympathetic drive in rats after myocardial infarction (MI). Approximately 24 hours after acute MI, rats received an intracerebroventricular injection (1 microL/min over 40 minutes) of clodronate liposomes (MI+CLOD) to eliminate brain perivascular macrophages, liposomes alone, or artificial cerebrospinal fluid. A week later, COX-2 immunoreactivity in perivascular macrophages and COX-2 mRNA and protein had increased in hypothalamic paraventricular nucleus of MI rats treated with artificial cerebrospinal fluid or liposomes alone compared with sham-operated rats. In MI+CLOD rats, neither perivascular macrophages nor COX-2 immunoreactivity was seen in the paraventricular nucleus, and COX-2 mRNA and protein levels were similar to those in sham-operated rats. Prostaglandin E(2) in cerebrospinal fluid, paraventricular nucleus neuronal excitation, and plasma norepinephrine were less in MI+CLOD rats than in MI rats treated with artificial cerebrospinal fluid or liposomes alone but more than in sham-operated rats. Intracerebroventricular CLOD had no effect on interleukin 1beta and tumor necrosis factor-alpha mRNA and protein in the paraventricular nucleus or plasma interleukin-1beta and tumor necrosis factor-alpha, which were increased in MI compared with sham-operated rats. In normal rats, pretreatment with intracerebroventricular CLOD reduced (P<0.05) the renal sympathetic, blood pressure, and heart rate responses to intracarotid artery injection of tumor necrosis factor-alpha (0.5 microg/kg); intracerebroventricular liposomes had no effect. The results suggest that proinflammatory cytokines stimulate sympathetic excitation after MI by inducing COX-2 activity and prostaglandin E(2) production in perivascular macrophages of the blood-brain barrier.
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Affiliation(s)
- Yang Yu
- Department of Veterans' Affairs Medical Center, Iowa City, Iowa, USA
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Gomez-Sanchez EP, Gomez-Sanchez CM, Plonczynski M, Gomez-Sanchez CE. Aldosterone synthesis in the brain contributes to Dahl salt-sensitive rat hypertension. Exp Physiol 2009; 95:120-30. [PMID: 19837774 DOI: 10.1113/expphysiol.2009.048900] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The enzymes required for aldosterone synthesis from cholesterol are expressed in rat and human brains. The hypertension of Dahl salt-sensitive (SS) rats is mitigated by the intracerebroventricular (i.c.v.) infusion of antagonists of the mineralocorticoid receptor (MR) and downstream effectors of mineralocorticoid action, as well as ablations of brain areas that also abrogate mineralocorticoid-salt excess hypertension in normotensive rats. We used real time RT-PCR to measure mRNA of aldosterone synthase and 11beta-hydroxylase, the requisite enzymes for the last step in the synthesis of aldosterone and corticosterone, respectively, MR and the determinants of MR ligand specificity, 11beta-hydroxysteroid dehydrogenase types 1 and 2 (11beta-HSD1&2) and hexose-6-phosphate dehydrogenase (H6PDH). A combination of extraction and ELISA was used to measure aldosterone concentrations in tissue and urine of SS and Sprague-Dawley (SD) rats. Aldosterone synthase mRNA expression was higher in the brains and lower in the adrenal glands of SS compared with SD rats. The amounts of mRNA for MR, 11beta-hydroxylase, 11beta-HSD1&2 and H6PD were similar. Aldosterone concentrations were greater in brains of SS than SD rats, yet, in keeping with the literature, the circulating and total aldosterone production of aldosterone in SS rats were not. The selective inhibitor of aldosterone synthase, FAD286, was infused i.c.v. or subcutaneously in a cross-over blood pressure study in hypertensive SS rats further challenged by a high-salt diet. The i.c.v. infusion of FAD286, at a dose that had no effect systemically, significantly and reversibly lowered blood pressure in SS rats. Aldosterone synthesis in brains of SS rats is greater than in SD rats and is important in the genesis of their salt-sensitive hypertension.
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Affiliation(s)
- Elise P Gomez-Sanchez
- Veterans Administration Medical Center (151), 1500 East Woodrow Wilson Drive, Jackson, MS, 39216-5199, USA.
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Felder RB, Yu Y, Zhang ZH, Wei SG. Pharmacological treatment for heart failure: a view from the brain. Clin Pharmacol Ther 2009; 86:216-20. [PMID: 19553933 DOI: 10.1038/clpt.2009.117] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Systolic heart failure is a feed-forward phenomenon with devastating consequences. Impaired cardiac function is the initiating event, but central nervous system mechanisms activated by persistent altered neural and humoral signals from the periphery play an important sustaining role. Animals with experimentally induced heart failure have neurochemical abnormalities in the brain that, when manipulated, profoundly affect sympathetic drive, volume regulation, and cardiac remodeling--critical determinants of outcome. This brief review explores recent studies that provide a strong rationale for the development of pharmaceutical agents that target central nervous system abnormalities in heart failure.
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Affiliation(s)
- R B Felder
- Medical Service, Department of Veterans Affairs Medical Center, Iowa City, Iowa, USA.
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30
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Huang BS, Leenen FHH. The brain renin-angiotensin-aldosterone system: A major mechanism for sympathetic hyperactivity and left ventricular remodeling and dysfunction after myocardial infarction. Curr Heart Fail Rep 2009; 6:81-8. [DOI: 10.1007/s11897-009-0013-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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31
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Ito K, Hirooka Y, Sunagawa K. Acquisition of brain Na sensitivity contributes to salt-induced sympathoexcitation and cardiac dysfunction in mice with pressure overload. Circ Res 2009; 104:1004-11. [PMID: 19299647 DOI: 10.1161/circresaha.108.188995] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In animal models of salt-sensitive hypertension, high salt augments sympathetic outflow via central mechanisms. It is not known, however, whether pressure overload affects salt sensitivity, thereby modifying central sympathetic outflow and cardiac function. We induced left ventricular hypertrophy with aortic banding in mice. Four weeks after aortic banding (AB-4), the left ventricle wall thickness was increased without changing the percentage fractional shortening. AB-4 mice were then fed either a high-salt (8%) diet or regular-salt diet for additional 4 weeks. Cardiac dysfunction, wall thickness, and 24-hour urinary catecholamine excretion were increased with high-salt diet compared with regular-salt diet. We then examined brain Na sensitivity. Intracerebroventricular infusion of high-Na (0.2 mol/L) artificial cerebrospinal fluid into AB-4 mice and mice Sham-4 increased urinary catecholamine excretion, arterial pressure, and heart rate more in AB-4 mice than in Sham-4 mice. Intracerebroventricular infusion of an epithelial Na channel blocker (benzamil) into mice with high-salt diet significantly decreased urinary catecholamine excretion and improved cardiac function. Infusion of either an angiotensin II type 1 receptor blocker or a Rho-kinase inhibitor also attenuated the salt-induced sympathetic hyperactivation and cardiac dysfunction in mice with high-salt diet. The levels of angiotensin II type 1 receptor and phosphorylated moesin, a substrate of Rho-kinase, were significantly greater in AB-4 mice than in Sham-4 mice. These results suggest that mice with pressure overload acquire brain Na sensitivity because of the activation of epithelial Na channel via Rho-kinase and angiotensin II, and this mechanism contributes to salt-induced sympathetic hyperactivation, further pressure overload, and cardiac dysfunction.
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Affiliation(s)
- Koji Ito
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
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Wei SG, Yu Y, Zhang ZH, Weiss RM, Felder RB. Mitogen-activated protein kinases mediate upregulation of hypothalamic angiotensin II type 1 receptors in heart failure rats. Hypertension 2008; 52:679-86. [PMID: 18768402 DOI: 10.1161/hypertensionaha.108.113639] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In heart failure (HF), angiotensin II type 1 receptor (AT(1)-R) expression is upregulated in brain regions regulating sympathetic drive, blood pressure, and body fluid homeostasis. However, the mechanism by which brain AT(1)-R are upregulated in HF remains unknown. The present study examined the hypothesis that the angiotensin II (Ang II)-triggered mitogen-activated protein kinases (MAPKs) p44/42, p38, and c-Jun N-terminal kinase contribute to upregulation of the AT(1)-R in the hypothalamus of rats with HF. AT(1)-R protein, AT(1)-R mRNA, and AT(1)-R immunoreactivity increased in the paraventricular nucleus of hypothalamus and the subfornical organ of rats with ischemia-induced HF compared with sham-operated controls. Phosphorylated p44/42 MAPK, c-Jun N-terminal kinase, and p38 MAPK also increased in paraventricular nucleus and subfornical organ. A 4-week ICV infusion of the AT(1)-R antagonist losartan decreased AT(1)-R protein and phosphorylation of p44/42 MAPK, c-Jun N-terminal kinase, and p38 MAPK in the HF rats. A 4-week ICV infusion of the p44/42 MAPK inhibitor PD98059 or the c-Jun N-terminal kinase inhibitor SP600125 significantly decreased AT(1)-R protein and AT(1)-R immunoreactivity in the paraventricular nucleus and subfornical organ, but the p38 MAPK inhibitor SB203580 did not. Treatment with ICV losartan, PD98059, and SP600125 had no effect on AT(1)-R expression by Western blot in sham-operated rats. In untreated HF rats 4 weeks after coronary ligation, a 3-hour ICV infusion of PD98059, SP600125, or losartan reduced AT(1)-R mRNA in paraventricular nucleus and subfornical organ. These data indicate that MAPK plays an important role in the upregulation of AT(1)-R in the rat forebrain in HF and suggest that Ang II upregulates its own receptor by this mechanism.
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Affiliation(s)
- Shun-Guang Wei
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, IA 52242, USA
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Wong HK, Bauer PO, Kurosawa M, Goswami A, Washizu C, Machida Y, Tosaki A, Yamada M, Knöpfel T, Nakamura T, Nukina N. Blocking acid-sensing ion channel 1 alleviates Huntington's disease pathology via an ubiquitin-proteasome system-dependent mechanism. Hum Mol Genet 2008; 17:3223-35. [DOI: 10.1093/hmg/ddn218] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Angiotensin-converting Enzyme Inhibitors, Inhibition of Brain and Peripheral Angiotensin-converting Enzymes, and Left Ventricular Dysfunction in Rats After Myocardial Infarction. J Cardiovasc Pharmacol 2008; 51:565-72. [DOI: 10.1097/fjc.0b013e318177090d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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36
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Sun Z, Bello-Roufai M, Wang X. RNAi inhibition of mineralocorticoid receptors prevents the development of cold-induced hypertension. Am J Physiol Heart Circ Physiol 2008; 294:H1880-7. [DOI: 10.1152/ajpheart.01319.2007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective was to determine whether the mineralocorticoid receptor (MR) plays a role in the initiation and development of cold-induced hypertension (CIH) by testing the hypothesis that the RNA interference (RNAi) inhibition of the MR attenuates CIH. The recombinant adeno-associated virus (AAV) carrying a short-hairpin small-interference RNA for MR (MRshRNA) or a scrambled sequence (ControlshRNA) was constructed. Six groups of albino mice were used (6 mice/group). Three groups were exposed to cold (6.7°C), whereas the remaining three groups were kept at room temperature (RT; warm) as controls. In each temperature condition, three groups received an intravenous injection of MRshRNA, ControlshRNA, or virus-free PBS, respectively, before exposure to cold. The viral complexes (0.35 × 1011 particles/mouse, 0.5 ml) or PBS (0.5 ml) was delivered into the circulation via the tail vein. The blood pressure (BP) of the mice treated with ControlshRNA or PBS increased significantly during exposure to cold, whereas the BP of the cold-exposed MRshRNA-treated mice did not increase and remained at the level of the control group kept at RT. Thus AAV delivery of MRshRNA prevented the initiation of CIH. MRshRNA significantly attenuated cardiac and renal hypertrophy. MRshRNA decreased the cold-induced increase in MR protein expression to the control level in the hypothalamus, kidneys, and heart, indicating an effective prevention of the cold-induced upregulation of MR. RNAi inhibition of MR resulted in significant decreases in the plasma level of norepinephrine, plasma renin activity, and plasma level of aldosterone in cold-exposed mice. MR played a critical role in the initiation and development of CIH. AAV delivery of MRshRNA may serve as a new approach for the prevention of cold-induced hypertension.
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Yu Y, Wei SG, Zhang ZH, Gomez-Sanchez E, Weiss RM, Felder RB. Does aldosterone upregulate the brain renin-angiotensin system in rats with heart failure? Hypertension 2008; 51:727-33. [PMID: 18227408 DOI: 10.1161/hypertensionaha.107.099796] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The brain renin-angiotensin system (RAS) contributes to increased sympathetic drive in heart failure (HF). The factors upregulating the brain RAS in HF remain unknown. We hypothesized that aldosterone (ALDO), a downstream product of the systemic RAS that crosses the blood-brain barrier, signals the brain to increase RAS activity in HF. We examined the relationship between circulating and brain ALDO in normal intact rats, in adrenalectomized rats receiving subcutaneous infusions of ALDO, and in rats with ischemia-induced HF and sham-operated controls. Brain ALDO levels were proportional to plasma ALDO levels across the spectrum of rats studied. Compared with sham-operated controls rats, HF rats had higher plasma and hypothalamic tissue levels of ALDO. HF rats also had higher expression of mRNA and protein for angiotensin-converting enzyme and angiotensin type 1 receptors in the hypothalamus, increased reduced nicotinamide-adenine dinucleotide phosphate oxidase activity and superoxide generation in the paraventricular nucleus of the hypothalamus, increased excitation of paraventricular nucleus neurons, and increased plasma norepinephrine. HF rats treated for 4 weeks with intracerebroventricular RU28318 (1 microg/h), a selective mineralocorticoid receptor antagonist, had less hypothalamic angiotensin-converting enzyme and angiotensin type 1 receptor mRNA and protein, less reduced nicotinamide-adenine dinucleotide phosphate-induced superoxide in the paraventricular nucleus, fewer excited paraventricular nucleus neurons, and lower plasma norepinephrine. RU28318 had no effect on plasma ALDO or on angiotensin-converting enzyme or angiotensin type 1 receptor expression in brain cortex. The data demonstrate that ALDO of adrenal origin enters the hypothalamus in direct proportion to plasma levels and suggest that ALDO contributes to the upregulation of hypothalamic RAS activity and sympathetic drive in heart failure.
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Affiliation(s)
- Yang Yu
- Department of Internal Medicine, University of Iowa, Iowa City 52242, USA
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38
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39
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Yu Y, Zhang ZH, Wei SG, Chu Y, Weiss RM, Heistad DD, Felder RB. Central gene transfer of interleukin-10 reduces hypothalamic inflammation and evidence of heart failure in rats after myocardial infarction. Circ Res 2007; 101:304-12. [PMID: 17569888 DOI: 10.1161/circresaha.107.148940] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The expression of proinflammatory cytokines increases in hypothalamus of rats with myocardial infarction (MI) and heart failure. We used central gene transfer of human interleukin (IL)-10, a potent antiinflammatory cytokine, to counter the effects of brain proinflammatory cytokines and examine their functional significance. Sprague-Dawley rats underwent coronary ligation to induce MI or sham surgery (SHAM). One week later, adenoviral vectors encoding human IL-10 (AdIL-10) or beta-galactosidase (betaGal) were injected (30 microL over 30 minutes) into lateral ventricle. One week after injection, there was abundant expression of human IL-10 in the brain of MI+AdIL-10 and SHAM+AdIL-10 rats. Compared with SHAM+betaGal, MI+betaGal had increased (P<0.05) IL-1beta and cyclooxygenase-2 mRNA and protein and nuclear factor kappaB activity in the hypothalamus, cyclooxygenase-2 fluorescence in perivascular cells of the paraventricular nucleus of hypothalamus, prostaglandin E(2) in cerebrospinal fluid, and Fra-like activity (indicating neuronal excitation) in paraventricular nucleus. Plasma norepinephrine levels, lung/body weight, right ventricle/body weight, and left ventricular end-diastolic pressure were increased and maximal left ventricular dP/dt was decreased. All of these findings were ameliorated in MI rats treated with AdIL-10. Hypothalamic tumor necrosis factor-alpha and circulating tumor necrosis factor-alpha and IL-1beta levels, also increased in MI+betaGal, were not affected by AdIL-10 treatment. Rat native IL-10 was not affected by MI or AdIL-10. AdIL-10 had no effects on SHAM rats. The results demonstrate that cardiovascular and autonomic mechanisms leading to heart failure after MI can be modulated by manipulating the balance between proinflammatory and antiinflammatory cytokines in the brain.
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Affiliation(s)
- Yang Yu
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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Abstract
With an increasingly aging population, the need for effective treatment of cardiovascular diseases (eg, heart failure, hypertension, and ischemic heart disease) cannot be overemphasized. The vital importance of mineralocorticoid receptor antagonists for treating cardiovascular conditions has only been appreciated in the last decade. The re-emergence of mineralocorticoid receptor antagonists has provided clinicians with an important tool towards complete blockade of the renin-angiotensin-aldosterone axis.
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Affiliation(s)
- Hari Krishnan Parthasarathy
- Hypertension Research Centre, Division of Medicine & Therapeutics, Ninewells Hospital & Medical School, University of Dundee, Dundee, Scotland, DD1 9SY, UK
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41
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Kang YM, Zhang ZH, Johnson RF, Yu Y, Beltz T, Johnson AK, Weiss RM, Felder RB. Novel effect of mineralocorticoid receptor antagonism to reduce proinflammatory cytokines and hypothalamic activation in rats with ischemia-induced heart failure. Circ Res 2006; 99:758-66. [PMID: 16960100 DOI: 10.1161/01.res.0000244092.95152.86] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Blocking brain mineralocorticoid receptors (MRs) reduces the high circulating levels of tumor necrosis factor (TNF)-alpha in heart failure (HF) rats. TNF-alpha and other proinflammatory cytokines activate neurons in the paraventricular nucleus (PVN) of hypothalamus, including corticotropin-releasing hormone (CRH) neurons, by inducing cyclooxygenase (COX)-2 activity and synthesis of prostaglandin E2 by perivascular cells of the cerebral vasculature. We tested the hypothesis that systemic treatment with a MR antagonist would reduce hypothalamic COX-2 expression and PVN neuronal activation in HF rats. Rats underwent coronary ligation to induce HF, confirmed by echocardiography, or sham surgery, followed by 6 weeks treatment with eplerenone (30 mg/kg per day, orally) or vehicle (drinking water). Eplerenone-treated HF rats had lower plasma TNF-alpha, interleukin (IL)-1beta and IL-6, less COX-2 staining of small blood vessels penetrating PVN, fewer PVN neurons expressing Fra-like activity (indicating chronic neuronal activation), and fewer PVN neurons staining for TNF-alpha, IL-1beta, and CRH than vehicle-treated HF rats. COX-2 and CRH protein expression in hypothalamus were 1.7- and 1.9-fold higher, respectively, in HF+vehicle versus sham+vehicle rats; these increases were attenuated (26% and 25%, respectively) in HF+eplerenone rats. Eplerenone-treated HF rats had less prostaglandin E2 in cerebrospinal fluid, lower plasma norepinephrine levels, lower left ventricular end-diastolic pressure, and lower right ventricle/body weight and lung/body weight ratios, but no improvement in left ventricular function. Treatment of HF rats with anticytokine agents, etanercept or pentoxifylline, produced very similar results. This study reveals a previously unrecognized effect of MR antagonism to minimize cytokine-induced central neural excitation in rats with HF.
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Affiliation(s)
- Yu-Ming Kang
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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Abstract
Hypertension - the chronic elevation of blood pressure - is a major human health problem. In most cases, the root cause of the disease remains unknown, but there is mounting evidence that many forms of hypertension are initiated and maintained by an elevated sympathetic tone. This review examines how the sympathetic tone to cardiovascular organs is generated, and discusses how elevated sympathetic tone can contribute to hypertension.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, Health Sciences Center, University of Virginia, 1300 Jefferson Park Avenue, Charlottesville, Virginia 22908-0735, USA.
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43
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Titze J, Luft FC, Bauer K, Dietsch P, Lang R, Veelken R, Wagner H, Eckardt KU, Hilgers KF. Extrarenal Na
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Balance, Volume, and Blood Pressure Homeostasis in Intact and Ovariectomized Deoxycorticosterone-Acetate Salt Rats. Hypertension 2006; 47:1101-7. [PMID: 16636196 DOI: 10.1161/01.hyp.0000221039.17735.1a] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Water-free Na+ storage may buffer extracellular volume and mean arterial pressure (MAP) in spite of Na+ retention. We studied the relationship among internal Na+, K+, water balance, and MAP in Sprague-Dawley rats, with or without deoxycorticosterone-acetate (DOCA) salt, with or without ovariectomy (OVX). The rats were fed a low-salt (0.1% NaCl) or high-salt (8% NaCl) diet for 5 weeks. DOCA salt increased MAP (161+/-14 versus 123+/-4 mm Hg; P<0.05), and DOCA-OVX salt increased MAP further (181+/-22 mm Hg; P<0.05). DOCA salt increased the total body Na+ by &40% to 45%; however, water-free Na+ retention by osmotically inactive Na+ storage and by osmotically neutral Na+/K+ exchange allowed the rats to maintain the extracellular volume close to normal. DOCA-OVX salt rats showed similar Na+ retention. However, their osmotically inactive Na+ storage capacity was greatly reduced and only partially compensated by neutral Na+/K+ exchange, resulting in greater volume retention despite similar Na+ retention. For every 1% wet weight total body water gain, MAP increased by 2.3+/-0.2 mm Hg in DOCA salt rats and 2.5+/-0.3 mm Hg in DOCA-OVX salt rats. Because water-free Na+ retention buffered total body water content by 8% to 11% wet weight, we conclude that this internal Na+ escape buffered MAP. Extrarenal Na+ and volume balance seem to play an important role in long-term volume and MAP control.
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Affiliation(s)
- Jens Titze
- Department of Nephrology and Hypertension, Friedrich-Alexander-University, Erlangen-Nürnberg, Germany.
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Amin MS, Wang HW, Reza E, Whitman SC, Tuana BS, Leenen FHH. Distribution of epithelial sodium channels and mineralocorticoid receptors in cardiovascular regulatory centers in rat brain. Am J Physiol Regul Integr Comp Physiol 2005; 289:R1787-97. [PMID: 16141309 DOI: 10.1152/ajpregu.00063.2005] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epithelial sodium channels (ENaC) are important for regulating sodium transport across epithelia. Functional studies indicate that neural mechanisms acting through mineralocorticoid receptors (MR) and sodium channels (presumably ENaC) are crucial to the development of sympathoexcitation and hypertension in experimental models of salt-sensitive hypertension. However, expression and localization of the ENaC in cardiovascular regulatory centers of the brain have not yet been studied. RT-PCR and immunohistochemistry were performed to study ENaC and MR expression at the mRNA and protein levels, respectively. Both mRNA and protein for alpha-, beta-, and gamma-ENaC subunits and MR were found to be expressed in the rat brain. All three ENaC subunits and MR were present in the supraoptic nucleus, magnocellular paraventricular nucleus, hippocampus, choroid plexus, ependyma, and brain blood vessels, suggesting the presence of multimeric channels and possible regulation by mineralocorticoids. In most cortical areas, thalamus, amygdala, and suprachiasmatic nucleus, notable expression of gamma-ENaC was undetectable, whereas alpha- and beta-ENaC were abundantly expressed pointing to the possibility of a heterogeneous population of channels. The findings suggest that stoichiometrically different populations of ENaC may be present in both epithelial and neural components in the brain, which may contribute to regulation of cerebrospinal fluid and interstitial Na+ concentration as well as neuronal excitation.
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Affiliation(s)
- Md Shahrier Amin
- Hypertension Unit, Univ. of Ottawa Heart Institute, Ottawa, ON, Canada K1Y 4W7
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