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Sato R, Vatic M, Peixoto da Fonseca GW, Anker SD, von Haehling S. Biological basis and treatment of frailty and sarcopenia. Cardiovasc Res 2024:cvae073. [PMID: 38828887 DOI: 10.1093/cvr/cvae073] [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: 07/27/2022] [Revised: 11/23/2022] [Accepted: 12/20/2022] [Indexed: 06/05/2024] Open
Abstract
In an ageing society, the importance of maintaining healthy life expectancy has been emphasized. As a result of age-related decline in functional reserve, frailty is a state of increased vulnerability and susceptibility to adverse health outcomes with a serious impact on healthy life expectancy. The decline in skeletal muscle mass and function, also known as sarcopenia, is key in the development of physical frailty. Both frailty and sarcopenia are highly prevalent in patients not only with advanced age but also in patients with illnesses that exacerbate their progression like heart failure (HF), cancer, or dementia, with the prevalence of frailty and sarcopenia in HF patients reaching up to 50-75% and 19.5-47.3%, respectively, resulting in 1.5-3 times higher 1-year mortality. The biological mechanisms of frailty and sarcopenia are multifactorial, complex, and not yet fully elucidated, ranging from DNA damage, proteostasis impairment, and epigenetic changes to mitochondrial dysfunction, cellular senescence, and environmental factors, many of which are further linked to cardiac disease. Currently, there is no gold standard for the treatment of frailty and sarcopenia, however, growing evidence supports that a combination of exercise training and nutritional supplement improves skeletal muscle function and frailty, with a variety of other therapies being devised based on the underlying pathophysiology. In this review, we address the involvement of frailty and sarcopenia in cardiac disease and describe the latest insights into their biological mechanisms as well as the potential for intervention through exercise, diet, and specific therapies.
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Affiliation(s)
- Ryosuke Sato
- Department of Cardiology and Pneumology, University of Göttingen Medical Center, Robert-Koch-Str. 40, 37075 Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
| | - Mirela Vatic
- Department of Cardiology and Pneumology, University of Göttingen Medical Center, Robert-Koch-Str. 40, 37075 Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
| | - Guilherme Wesley Peixoto da Fonseca
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Stefan D Anker
- Department of Cardiology (CVK) of German Heart Center Charité; German Centre for Cardiovascular Research (DZHK) partner site Berlin, Charité Universitätsmedizin, Berlin, Germany
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
| | - Stephan von Haehling
- Department of Cardiology and Pneumology, University of Göttingen Medical Center, Robert-Koch-Str. 40, 37075 Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
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van Thiel BS, van der Linden J, Ridwan Y, Garrelds IM, Vermeij M, Clahsen-van Groningen MC, Qadri F, Alenina N, Bader M, Roks AJM, Danser AHJ, Essers J, van der Pluijm I. In Vivo Renin Activity Imaging in the Kidney of Progeroid Ercc1 Mutant Mice. Int J Mol Sci 2021; 22:ijms222212433. [PMID: 34830315 PMCID: PMC8619549 DOI: 10.3390/ijms222212433] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 11/08/2021] [Accepted: 11/12/2021] [Indexed: 12/21/2022] Open
Abstract
Changes in the renin–angiotensin system, known for its critical role in the regulation of blood pressure and sodium homeostasis, may contribute to aging and age-related diseases. While the renin–angiotensin system is suppressed during aging, little is known about its regulation and activity within tissues. However, this knowledge is required to successively treat or prevent renal disease in the elderly. Ercc1 is involved in important DNA repair pathways, and when mutated causes accelerated aging phenotypes in humans and mice. In this study, we hypothesized that unrepaired DNA damage contributes to accelerated kidney failure. We tested the use of the renin-activatable near-infrared fluorescent probe ReninSense680™ in progeroid Ercc1d/− mice and compared renin activity levels in vivo to wild-type mice. First, we validated the specificity of the probe by detecting increased intrarenal activity after losartan treatment and the virtual absence of fluorescence in renin knock-out mice. Second, age-related kidney pathology, tubular anisokaryosis, glomerulosclerosis and increased apoptosis were confirmed in the kidneys of 24-week-old Ercc1d/− mice, while initial renal development was normal. Next, we examined the in vivo renin activity in these Ercc1d/− mice. Interestingly, increased intrarenal renin activity was detected by ReninSense in Ercc1d/− compared to WT mice, while their plasma renin concentrations were lower. Hence, this study demonstrates that intrarenal RAS activity does not necessarily run in parallel with circulating renin in the aging mouse. In addition, our study supports the use of this probe for longitudinal imaging of altered RAS signaling in aging.
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Affiliation(s)
- Bibi S. van Thiel
- Department of Molecular Genetics, Cancer Genomics Center, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (B.S.v.T.); (J.v.d.L.); (Y.R.)
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (I.M.G.); (A.J.M.R.); (A.H.J.D.)
- Department of Vascular Surgery, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands
| | - Janette van der Linden
- Department of Molecular Genetics, Cancer Genomics Center, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (B.S.v.T.); (J.v.d.L.); (Y.R.)
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (I.M.G.); (A.J.M.R.); (A.H.J.D.)
- Department of Experimental Cardiology, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands
| | - Yanto Ridwan
- Department of Molecular Genetics, Cancer Genomics Center, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (B.S.v.T.); (J.v.d.L.); (Y.R.)
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (I.M.G.); (A.J.M.R.); (A.H.J.D.)
| | - Ingrid M. Garrelds
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (I.M.G.); (A.J.M.R.); (A.H.J.D.)
| | - Marcel Vermeij
- Department of Pathology, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (M.V.); (M.C.C.-v.G.)
| | | | | | - Natalia Alenina
- Max Delbrück Center, 13125 Berlin, Germany; (F.Q.); (N.A.); (M.B.)
- DZHK (German Center for Cardiovascular Research), Partner Site Berlin, 10785 Berlin, Germany
| | - Michael Bader
- Max Delbrück Center, 13125 Berlin, Germany; (F.Q.); (N.A.); (M.B.)
- DZHK (German Center for Cardiovascular Research), Partner Site Berlin, 10785 Berlin, Germany
- Charité—University Medicine, 10117 Berlin, Germany
- Institute for Biology, University of Lübeck, 23562 Lübeck, Germany
| | - Anton J. M. Roks
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (I.M.G.); (A.J.M.R.); (A.H.J.D.)
| | - A. H. Jan Danser
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (I.M.G.); (A.J.M.R.); (A.H.J.D.)
| | - Jeroen Essers
- Department of Molecular Genetics, Cancer Genomics Center, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (B.S.v.T.); (J.v.d.L.); (Y.R.)
- Department of Vascular Surgery, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands
- Department of Radiation Oncology, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands
- Correspondence: (J.E.); (I.v.d.P.); Tel.: +31-10-7043604 (J.E.); +31-10-7043724 (I.v.d.P.); Fax: +31-10-7044743 (J.E. & I.v.d.P.)
| | - Ingrid van der Pluijm
- Department of Molecular Genetics, Cancer Genomics Center, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands; (B.S.v.T.); (J.v.d.L.); (Y.R.)
- Department of Vascular Surgery, Erasmus University Medical Center, 3015GD Rotterdam, The Netherlands
- Correspondence: (J.E.); (I.v.d.P.); Tel.: +31-10-7043604 (J.E.); +31-10-7043724 (I.v.d.P.); Fax: +31-10-7044743 (J.E. & I.v.d.P.)
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Spatio-temporal correlates of gene expression and cortical morphology across lifespan and aging. Neuroimage 2020; 224:117426. [PMID: 33035668 DOI: 10.1016/j.neuroimage.2020.117426] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 09/29/2020] [Accepted: 09/29/2020] [Indexed: 11/23/2022] Open
Abstract
Evidence from neuroimaging and genetic studies supports the concept that brain aging mirrors development. However, it is unclear whether mechanisms linking brain development and aging provide new insights to delay aging and potentially reverse it. This study determined biological mechanisms and phenotypic traits underpinning brain alterations across the lifespan and in aging by examining spatio-temporal correlations between gene expression and cortical volumes using datasets d with the age range from 2 to 82 years. We revealed that a large proportion of genes whose expression was associated with cortical volumes across the lifespan were in astrocytes. These genes, which showed up-regulation during development and down-regulation during aging, contributed to fundamental homeostatic functions of astrocytes. Included among these genes were those encoding components of cAMP, Ras, and retrograde endocannabinoid signaling pathways. Genes associated with cortical volumes in the same data aged above 55 years were also enriched for the sphingolipid, renin-angiotensin system (RAS), proteasome, and TGF-β signaling pathway, which is linked to senescence-associated secretory phenotypes. Neuroticism, drinking, and smoking were the common phenotypic traits in the lifespan and aging, while memory was the unique phenotype associated with aging. These findings provide biological mechanisms mirroring development and aging as well as unique to aging.
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Obert LA, Frazier KS. Intrarenal Renin–Angiotensin System Involvement in the Pathogenesis of Chronic Progressive Nephropathy—Bridging the Informational Gap Between Disciplines. Toxicol Pathol 2019; 47:799-816. [DOI: 10.1177/0192623319861367] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Chronic progressive nephropathy (CPN) is the most commonly encountered spontaneous background finding in laboratory rodents. Various theories on its pathogenesis have been proposed, but there is a paucity of data regarding specific mechanisms or physiologic pathways involved in early CPN development. The current CPN mechanism of action for tumorigenesis is largely based on its associated increase in tubular cell proliferation without regard to preceding subcellular degenerative changes. Combing through the published literature from multiple biology disciplines provided insight into the preceding cellular events. Mechanistic pathways involved in the progressive age-related decline in rodent kidney function and several key inflexion points have been identified. These critical pathway factors were then connected using data from renal models from multiple rodent strains, other species, and mechanistic work in humans to form a cohesive picture of pathways and protein interactions. Abundant data linked similar renal pathologies to local events involving hypoxia (hypoxia-inducible factor 1α), altered intrarenal renin–angiotensin system (RAS), oxidative stress (nitric oxide), and pro-inflammatory pathways (transforming growth factor β), with positive feedback loops and downstream effectors amplifying the injury and promoting scarring. Intrarenal RAS alterations seem to be central to all these events and may be critical to CPN development and progression.
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Jang IA, Kim EN, Lim JH, Kim MY, Ban TH, Yoon HE, Park CW, Chang YS, Choi BS. Effects of Resveratrol on the Renin-Angiotensin System in the Aging Kidney. Nutrients 2018; 10:E1741. [PMID: 30424556 PMCID: PMC6267480 DOI: 10.3390/nu10111741] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/02/2018] [Accepted: 11/09/2018] [Indexed: 02/07/2023] Open
Abstract
The renin-angiotensin system (RAS), especially the angiotensin II (Ang II)/angiotensin II type 1 receptor (AT1R) axis, plays an important role in the aging process of the kidney, through increased tissue reactive oxygen species production and progressively increased oxidative stress. In contrast, the angiotensin 1-7 (Ang 1-7)/Mas receptor (MasR) axis, which counteracts the effects of Ang II, is protective for end-organ damage. To evaluate the ability of resveratrol (RSV) to modulate the RAS in aging kidneys, eighteen-month-old male C57BL/6 mice were divided into two groups that received either normal mouse chow or chow containing resveratrol, for six months. Renal expressions of RAS components, as well as pro- and antioxidant enzymes, were measured and mouse kidneys were isolated for histopathology. Resveratrol-treated mice demonstrated better renal function and reduced albuminuria, with improved renal histologic findings. Resveratrol suppressed the Ang II/AT1R axis and enhanced the AT2R/Ang 1-7/MasR axis. Additionally, the expression of nicotinamide adenine dinucleotide phosphate oxidase 4, 8-hydroxy-2'-deoxyguanosine, 3-nitrotyrosine, collagen IV, and fibronectin was decreased, while the expression of endothelial nitric oxide synthase and superoxide dismutase 2 was increased by resveratrol treatment. These findings demonstrate that resveratrol exerts protective effects on aging kidneys by reducing oxidative stress, inflammation, and fibrosis, through Ang II suppression and MasR activation.
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Affiliation(s)
- In-Ae Jang
- Department of Internal medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
| | - Eun Nim Kim
- Division of Medical Cell Biology, Department of Biomedical Science, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
| | - Ji Hee Lim
- Division of Medical Cell Biology, Department of Biomedical Science, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
| | - Min Young Kim
- Division of Medical Cell Biology, Department of Biomedical Science, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
| | - Tae Hyun Ban
- Department of Internal medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
- Division of Nephrology, Department of Internal Medicine, Seoul St. Mary's Hospital, Seoul 06591, Korea.
| | - Hye Eun Yoon
- Department of Internal medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
- Division of Nephrology, Department of Internal Medicine, Incheon St. Mary's Hospital, Incheon 21431, Korea.
| | - Cheol Whee Park
- Department of Internal medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
- Division of Nephrology, Department of Internal Medicine, Seoul St. Mary's Hospital, Seoul 06591, Korea.
| | - Yoon Sik Chang
- Department of Internal medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
- Division of Nephrology, Department of Internal Medicine, Yeouido St. Mary's Hospital, Seoul 07345, Korea.
| | - Bum Soon Choi
- Department of Internal medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
- Division of Nephrology, Department of Internal Medicine, St. Paul's Hospital, Seoul 02559, Korea.
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Hezel M, Peleli M, Liu M, Zollbrecht C, Jensen BL, Checa A, Giulietti A, Wheelock CE, Lundberg JO, Weitzberg E, Carlström M. Dietary nitrate improves age-related hypertension and metabolic abnormalities in rats via modulation of angiotensin II receptor signaling and inhibition of superoxide generation. Free Radic Biol Med 2016; 99:87-98. [PMID: 27474450 DOI: 10.1016/j.freeradbiomed.2016.07.025] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 07/06/2016] [Accepted: 07/25/2016] [Indexed: 12/14/2022]
Abstract
Advanced age is associated with increased risk for cardiovascular disease and type 2 diabetes. A proposed central event is diminished amounts of nitric oxide (NO) due to reduced generation by endothelial NO synthase (eNOS) and increased oxidative stress. In addition, it is widely accepted that increased angiotensin II (ANG II) signaling is also implicated in the pathogenesis of endothelial dysfunction and hypertension by accelerating formation of reactive oxygen species. This study was designed to test the hypothesis that dietary nitrate supplementation could reduce blood pressure and improve glucose tolerance in aged rats, via attenuation of NADPH oxidase activity and ANG II receptor signaling. Dietary nitrate supplementation for two weeks reduced blood pressure (10-15mmHg) and improved glucose clearance in old, but not in young rats. These favorable effects were associated with increased insulin responses, reduced plasma creatinine as well as improved endothelial relaxation to acetylcholine and attenuated contractility to ANG II in resistance arteries. Mechanistically, nitrate reduced NADPH oxidase-mediated oxidative stress in the cardiovascular system and increased cGMP signaling. Finally, nitrate treatment in aged rats normalized the gene expression profile of ANG II receptors (AT1A, AT2, AT1A/AT2 ratio) in the renal and cardiovascular systems without altering plasma levels of renin or ANG II. Our results show that boosting the nitrate-nitrite-NO pathway can partly compensate for age-related disturbances in endogenous NO generation via inhibition of NADPH oxidase and modulation of ANG II receptor expression. These novel findings may have implications for nutrition-based preventive and therapeutic strategies against cardiovascular and metabolic diseases.
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Affiliation(s)
- Michael Hezel
- Department of Physiology and Pharmacology, Karolinska Institutet, S-17177 Stockholm, Sweden.
| | - Maria Peleli
- Department of Physiology and Pharmacology, Karolinska Institutet, S-17177 Stockholm, Sweden
| | - Ming Liu
- Department of Physiology and Pharmacology, Karolinska Institutet, S-17177 Stockholm, Sweden
| | - Christa Zollbrecht
- Department of Physiology and Pharmacology, Karolinska Institutet, S-17177 Stockholm, Sweden
| | - Boye L Jensen
- Department of Cardiovascular and Renal Research, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Antonio Checa
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-17177 Stockholm, Sweden
| | - Alessia Giulietti
- Department of Physiology and Pharmacology, Karolinska Institutet, S-17177 Stockholm, Sweden
| | - Craig E Wheelock
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-17177 Stockholm, Sweden
| | - Jon O Lundberg
- Department of Physiology and Pharmacology, Karolinska Institutet, S-17177 Stockholm, Sweden
| | - Eddie Weitzberg
- Department of Physiology and Pharmacology, Karolinska Institutet, S-17177 Stockholm, Sweden
| | - Mattias Carlström
- Department of Physiology and Pharmacology, Karolinska Institutet, S-17177 Stockholm, Sweden.
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Age-Associated Changes in the Vascular Renin-Angiotensin System in Mice. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:6731093. [PMID: 27200147 PMCID: PMC4855022 DOI: 10.1155/2016/6731093] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 03/08/2016] [Accepted: 03/31/2016] [Indexed: 11/25/2022]
Abstract
Background. This study evaluated whether the change in the renin-angiotensin system (RAS) is associated with arterial aging in mice. Methods. Histologic changes and expressions of transforming growth factor-β (TGF-β), collagen IV, fibronectin, angiotensin II (Ang II), angiotensin-converting enzyme (ACE), angiotensin-converting enzyme 2 (ACE2), angiotensin II type 1 receptor (AT1R), angiotensin II type 2 receptor (AT2R), prorenin receptor (PRR), Mas receptor (MasR), endothelial nitric oxide synthase (eNOS), NADPH oxidase 2 and oxidase 4 (Nox2 and Nox4), 8-hydroxy-2′-deoxyguanosine (8-OHdG), 3-nitrotyrosine, and superoxide dismutase 1 and dismutase 2 (SOD1 and SOD2) were measured in the thoracic aortas from 2-month-old, 12-month-old, and 24-month-old C57/BL6 mice. Results. Twenty-four-month-old mice showed significantly increased aortic media thickness and expressions of TGF-β, collagen IV, and fibronectin, compared to 2-month-old and 12-month-old mice. The expressions of PRR, ACE, and Ang II, and AT1R-positive area significantly increased, whereas expressions of ACE2 and MasR and AT2R-positive area decreased with age. The expressions of phosphorylated serine1177-eNOS, SOD1, and SOD2 decreased, and the 8-OHdG-positive area and the 3-nitrotyrosine-positive area increased with age. The expression of Nox2 significantly increased with age, but that of Nox4 did not change. Conclusions. The enhanced PRR-ACE-Ang II-AT1R axis and reduced ACE2-MasR axis were associated with arterial aging in mice.
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Chappell MC. Biochemical evaluation of the renin-angiotensin system: the good, bad, and absolute? Am J Physiol Heart Circ Physiol 2015; 310:H137-52. [PMID: 26475588 DOI: 10.1152/ajpheart.00618.2015] [Citation(s) in RCA: 172] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/15/2015] [Indexed: 02/07/2023]
Abstract
The renin-angiotensin system (RAS) constitutes a key hormonal system in the physiological regulation of blood pressure through peripheral and central mechanisms. Indeed, dysregulation of the RAS is considered a major factor in the development of cardiovascular pathologies, and pharmacological blockade of this system by the inhibition of angiotensin-converting enzyme (ACE) or antagonism of the angiotensin type 1 receptor (AT1R) offers an effective therapeutic regimen. The RAS is now defined as a system composed of different angiotensin peptides with diverse biological actions mediated by distinct receptor subtypes. The classic RAS comprises the ACE-ANG II-AT1R axis that promotes vasoconstriction; water intake; sodium retention; and increased oxidative stress, fibrosis, cellular growth, and inflammation. In contrast, the nonclassical RAS composed primarily of the ANG II/ANG III-AT2R and the ACE2-ANG-(1-7)-AT7R pathways generally opposes the actions of a stimulated ANG II-AT1R axis. In lieu of the complex and multifunctional aspects of this system, as well as increased concerns on the reproducibility among laboratories, a critical assessment is provided on the current biochemical approaches to characterize and define the various components that ultimately reflect the status of the RAS.
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Affiliation(s)
- Mark C Chappell
- The Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina
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de Cavanagh EMV, Inserra F, Ferder L. Angiotensin II blockade: how its molecular targets may signal to mitochondria and slow aging. Coincidences with calorie restriction and mTOR inhibition. Am J Physiol Heart Circ Physiol 2015; 309:H15-44. [PMID: 25934099 DOI: 10.1152/ajpheart.00459.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 04/30/2015] [Indexed: 02/07/2023]
Abstract
Caloric restriction (CR), renin angiotensin system blockade (RAS-bl), and rapamycin-mediated mechanistic target of rapamycin (mTOR) inhibition increase survival and retard aging across species. Previously, we have summarized CR and RAS-bl's converging effects, and the mitochondrial function changes associated with their physiological benefits. mTOR inhibition and enhanced sirtuin and KLOTHO signaling contribute to the benefits of CR in aging. mTORC1/mTORC2 complexes contribute to cell growth and metabolic regulation. Prolonged mTORC1 activation may lead to age-related disease progression; thus, rapamycin-mediated mTOR inhibition and CR may extend lifespan and retard aging through mTORC1 interference. Sirtuins by deacetylating histone and transcription-related proteins modulate signaling and survival pathways and mitochondrial functioning. CR regulates several mammalian sirtuins favoring their role in aging regulation. KLOTHO/fibroblast growth factor 23 (FGF23) contribute to control Ca(2+), phosphate, and vitamin D metabolism, and their dysregulation may participate in age-related disease. Here we review how mTOR inhibition extends lifespan, how KLOTHO functions as an aging suppressor, how sirtuins mediate longevity, how vitamin D loss may contribute to age-related disease, and how they relate to mitochondrial function. Also, we discuss how RAS-bl downregulates mTOR and upregulates KLOTHO, sirtuin, and vitamin D receptor expression, suggesting that at least some of RAS-bl benefits in aging are mediated through the modulation of mTOR, KLOTHO, and sirtuin expression and vitamin D signaling, paralleling CR actions in age retardation. Concluding, the available evidence endorses the idea that RAS-bl is among the interventions that may turn out to provide relief to the spreading issue of age-associated chronic disease.
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Affiliation(s)
- Elena M V de Cavanagh
- Center of Hypertension, Cardiology Department, Austral University Hospital, Derqui, Argentina; School of Biomedical Sciences, Austral University, Buenos Aires, Argentina; and
| | - Felipe Inserra
- Center of Hypertension, Cardiology Department, Austral University Hospital, Derqui, Argentina; School of Biomedical Sciences, Austral University, Buenos Aires, Argentina; and
| | - León Ferder
- Department of Physiology and Pharmacology, Ponce School of Medicine, Ponce, Puerto Rico
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Kadoguchi T, Kinugawa S, Takada S, Fukushima A, Furihata T, Homma T, Masaki Y, Mizushima W, Nishikawa M, Takahashi M, Yokota T, Matsushima S, Okita K, Tsutsui H. Angiotensin II can directly induce mitochondrial dysfunction, decrease oxidative fibre number and induce atrophy in mouse hindlimb skeletal muscle. Exp Physiol 2015; 100:312-22. [DOI: 10.1113/expphysiol.2014.084095] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 01/08/2015] [Indexed: 12/22/2022]
Affiliation(s)
- Tomoyasu Kadoguchi
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Shintaro Kinugawa
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Shingo Takada
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Arata Fukushima
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Takaaki Furihata
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Tsuneaki Homma
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Yoshihiro Masaki
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Wataru Mizushima
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Mikito Nishikawa
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Masashige Takahashi
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Takashi Yokota
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Shouji Matsushima
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
| | - Koichi Okita
- Graduate School of Lifelong Sport; Hokusho University; Hokkaido Ebetsu Japan
| | - Hiroyuki Tsutsui
- Department of Cardiovascular Medicine; Hokkaido University Graduate School of Medicine; Kita-ku, Hokkaido Sapporo Japan
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Simon CB, Lee-McMullen B, Phelan D, Gilkes J, Carter CS, Buford TW. The renin-angiotensin system and prevention of age-related functional decline: where are we now? AGE (DORDRECHT, NETHERLANDS) 2015; 37:9753. [PMID: 25663422 PMCID: PMC4320995 DOI: 10.1007/s11357-015-9753-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 01/27/2015] [Indexed: 05/19/2023]
Abstract
Declining physical function is a major health problem for older adults as it is associated with multiple comorbidities and mortality. Exercise has been shown to improve physical function, though response to exercise is variable. Conversely, drugs targeting the renin-angiotensin system (RAS) pathway, including angiotensin-converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARBs), are also reported to improve physical function. In the past decade, significant strides have been made to understand the complexity and specificity of the RAS system as it pertains to physical function in older adults. Prior findings have also determined that interactions between antihypertensive medications and exercise may influence physical function above and beyond either factor alone. We review the latest research on RAS, exercise, and physical function for older adults. We also outline future research aims in this area, including genetic influences and clinical phenotyping, for the purpose of maintaining or improving physical function through tailored treatments.
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Affiliation(s)
- Corey B. Simon
- />Pain Research and Intervention Center of Excellence, University of Florida, Gainesville, FL USA
| | - Brittany Lee-McMullen
- />Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL USA
| | - Dane Phelan
- />Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL USA
| | - Janine Gilkes
- />Department of Medicine, College of Medicine, University of Florida, Gainesville, FL USA
| | - Christy S. Carter
- />Department of Aging and Geriatric Research, College of Medicine, University of Florida, Gainesville, FL USA
| | - Thomas W. Buford
- />Department of Aging and Geriatric Research, College of Medicine, University of Florida, Gainesville, FL USA
- />Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL USA
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12
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Abstract
The effects of brain AngII (angiotensin II) depend on AT(1) receptor (AngII type 1 receptor) stimulation and include regulation of cerebrovascular flow, autonomic and hormonal systems, stress, innate immune response and behaviour. Excessive brain AT(1) receptor activity associates with hypertension and heart failure, brain ischaemia, abnormal stress responses, blood-brain barrier breakdown and inflammation. These are risk factors leading to neuronal injury, the incidence and progression of neurodegerative, mood and traumatic brain disorders, and cognitive decline. In rodents, ARBs (AT(1) receptor blockers) ameliorate stress-induced disorders, anxiety and depression, protect cerebral blood flow during stroke, decrease brain inflammation and amyloid-β neurotoxicity and reduce traumatic brain injury. Direct anti-inflammatory protective effects, demonstrated in cultured microglia, cerebrovascular endothelial cells, neurons and human circulating monocytes, may result not only in AT(1) receptor blockade, but also from PPARγ (peroxisome-proliferator-activated receptor γ) stimulation. Controlled clinical studies indicate that ARBs protect cognition after stroke and during aging, and cohort analyses reveal that these compounds significantly reduce the incidence and progression of Alzheimer's disease. ARBs are commonly used for the therapy of hypertension, diabetes and stroke, but have not been studied in the context of neurodegenerative, mood or traumatic brain disorders, conditions lacking effective therapy. These compounds are well-tolerated pleiotropic neuroprotective agents with additional beneficial cardiovascular and metabolic profiles, and their use in central nervous system disorders offers a novel therapeutic approach of immediate translational value. ARBs should be tested for the prevention and therapy of neurodegenerative disorders, in particular Alzheimer's disease, affective disorders, such as co-morbid cardiovascular disease and depression, and traumatic brain injury.
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Affiliation(s)
- Juan M Saavedra
- Section on Pharmacology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
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13
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Chugh G, Pokkunuri I, Asghar M. Renal dopamine and angiotensin II receptor signaling in age-related hypertension. Am J Physiol Renal Physiol 2012; 304:F1-7. [PMID: 23097467 DOI: 10.1152/ajprenal.00441.2012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Kidneys play a vital role in long-term regulation of blood pressure. This is achieved by actions of many renal and nonrenal factors acting on the kidney that help maintain the body's water and electrolyte balance and thus control blood pressure. Several endogenously formed or circulating hormones/peptides, by acting within the kidney, regulate fluid and water homeostasis and blood pressure. Dopamine and angiotensin II are the two key renal factors that, via acting on their receptors and counterregulating each other's function, maintain water and sodium balance. In this review, we provide recent advances in the signaling cascades of these renal receptors, especially at the level of their cross talk, and discuss their roles in blood pressure regulation in the aging process.
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Affiliation(s)
- Gaurav Chugh
- Heart and Kidney Institute, College of Pharmacy, Univ. of Houston, Houston, TX 77204, USA
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14
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Abstract
Aging is associated with an imbalance in sympathetic and parasympathetic outflow to cardiovascular effector organs. This autonomic imbalance contributes to the decline in cardiovagal baroreceptor reflex function during aging, which allows for unrestrained activation of the sympathetic nervous system to negatively impact resting systolic blood pressure and its variability. Further, impaired baroreflex function can contribute to the development of insulin resistance and other features of the metabolic syndrome during aging through overlap in autonomic neural pathways that regulate both cardiovascular and metabolic functions. Increasing evidence supports a widespread influence of the renin-angiotensin system (RAS) on both sympathetic and parasympathetic activity through receptors distributed to peripheral and central sites of action. Indeed, therapeutic interventions to block the RAS are well established for the treatment of hypertension in elderly patients, and reduce the incidence of new-onset diabetes in clinical trials. Further, RAS blockade increases lifespan and improves numerous age-related pathologies in rodents, often independent of blood pressure. The beneficial effects of these interventions are at least in part attributed to suppression of angiotensin II formed locally within the brain. In particular, recent insights from transgenic rodents provide evidence that long-term alteration in the brain RAS modulates the balance between angiotensin II and angiotensin-(1-7), and related intracellular signaling pathways, to influence cardiovascular and metabolic function in the context of hypertension and aging.
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15
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Nautiyal M, Shaltout HA, de Lima DC, do Nascimento K, Chappell MC, Diz DI. Central angiotensin-(1-7) improves vagal function independent of blood pressure in hypertensive (mRen2)27 rats. Hypertension 2012; 60:1257-65. [PMID: 23045456 DOI: 10.1161/hypertensionaha.112.196782] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypertensive transgenic (mRen2)27 rats with overexpression of the mRen2 gene have impaired baroreflex sensitivity for heart rate control and high nicotinamide adenine dinucleotide phosphate oxidase and kinase-to-phosphatase signaling activity in medullary tissue compared with normotensive Hannover Sprague-Dawley control rats. They also exhibit insulin resistance at a young age. To determine whether blocking angiotensin II actions, supplementing angiotensin-(1-7), or scavenging reactive oxygen species in brain differentially alters mean arterial pressure, baroreflex sensitivity, or metabolic function, while altering medullary signaling pathways in these animals, we compared intracerebroventricular infusions of the angiotensin II type 1 receptor antagonist candesartan (4 μg/5 μL/h), angiotensin-(1-7) (0.1 μg/5 μL/h), a reactive oxygen species scavenger tempol (25 μg/5 μL/h), or artificial cerebrospinal fluid (5 μL/h) for 2 weeks. Mean arterial pressure was reduced in candesartan-treated rats without significantly improving the vagal components of baroreflex function or heart rate variability. In contrast, angiotensin-(1-7) treatment significantly improved the vagal components of baroreflex function and heart rate variability at a dose that did not significantly lower mean arterial pressure. Tempol significantly reduced nicotinamide adenine dinucleotide phosphate oxidase activity in brain dorsal medullary tissue but had no effect on mean arterial pressure or autonomic function. Candesartan tended to reduce fat mass, but none of the treatments significantly altered indices of metabolic function or mitogen-activated protein kinase signaling pathways in dorsal medulla. Although additional dose response studies are necessary to determine the potential maximal effectiveness of each treatment, the current findings demonstrate that blood pressure and baroreflex function can be essentially normalized independently of medullary nicotinamide adenine dinucleotide phosphate oxidase or mitogen-activated protein kinase in hypertensive (mRen2)27 rats.
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Affiliation(s)
- Manisha Nautiyal
- Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1032, USA
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16
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Marques MB, Ribeiro-Oliveira A, Guimarães J, Nascimento GF, Anjos AP, Vilas-Boas WW, Santos RAS, Thomas JD, Igreja SM, Grossman AB, Kola B, Korbonits M. Modifications in basal and stress-induced hypothalamic AMP-activated protein kinase (AMPK) activity in rats chronically treated with an angiotensin II receptor blocker. Stress 2012; 15:554-61. [PMID: 22217206 DOI: 10.3109/10253890.2011.648673] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
5' adenosine monophosphate-activated protein kinase (AMPK) plays a prominent role as a metabolic stress sensor. The role of hypothalamic AMPK in response to restraint and surgical stress has not been previously investigated. It has been recently suggested that the renin-angiotensin system, in addition to its role in stress regulation, may play a significant role in regulating metabolic pathways including the regulation of the AMPK system. This study was thus aimed to evaluate the effects of candesartan, an angiotensin II AT1 receptor blocker drug, on hypothalamic AMPK activity under basal conditions and after restraint in conscious rats or after surgical stress under general anesthesia. Male Wistar rats were treated with 5 mg/kg/day candesartan in the drinking water for 2 weeks. The hypothalamic AMPK activity was determined under basal and stress conditions, using a kinase activity assay. Chronic administration of candesartan significantly increased hypothalamic AMPK activity. Hypothalamic AMPK activity was also increased by restraint stress whereas no change was observed during surgical stress under anesthesia. The high levels of hypothalamic AMPK activation observed in candesartan-treated rats were not changed by restraint stress but were reduced to control levels by anesthesia and surgery. In conclusion, chronic candesartan treatment and restraint stress in conscious rats stimulate the hypothalamic AMPK activity, whereas surgical stress under anesthesia inhibits pathways regulating the AMPK activity even in candesartan-treated rats.
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Affiliation(s)
- Mirna B Marques
- Department of Internal Medicine, School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Brazil.
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17
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Low glial angiotensinogen improves body habitus, diastolic function, and exercise tolerance in aging male rats. Cardiovasc Endocrinol 2012; 1:49-58. [PMID: 23795309 DOI: 10.1097/xce.0b013e32835a2159] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVES Long-term systemic blockade of the renin-angiotensin system (RAS) with either an angiotensin (Ang) II type 1 receptor antagonist or an angiotensin-converting enzyme inhibitor attenuates age-related cardiac remodeling and oxidative damage, and improves myocardial relaxation. However, the role of the brain RAS in mediating the development of diastolic dysfunction during aging is not known. We hypothesized that low brain RAS protects against the development of age-related diastolic dysfunction and left ventricular remodeling. METHODS Sixty-week-old transgenic male ASrAOGEN rats (n =9), with normal circulating Ang II and functionally low brain Ang II, because of a GFAP promoter-linked angiotensinogen antisense targeted to glia, and age-matched and sex-matched Hannover Sprague-Dawley (SD; n= 9) rats, with normal levels of both circulating and brain Ang II, underwent echocardiograms to evaluate cardiac structure and function. Postmortem hearts were further compared for histological, molecular, and biochemical changes consistent with cardiac aging. RESULTS ASrAOGEN rats showed preserved systolic and diastolic function at mid-life and this was associated with a lower, more favorable ratio of the phospholamban-SERCA2 ratio, reduced incidence of histological changes in the left ventricle, and increased cardiac Ang-(1-7) when compared with the in-vivo functional, and ex-vivo structural and biochemical indices from age-matched SD rats. Moreover, ASrAOGEN rats had lower percent body fat and a superior exercise tolerance when compared with SD rats of the same age. CONCLUSION Our data indicate that the central RAS plays a role in the maintenance of diastolic function and exercise tolerance in mid-life and this may be related to effects on body habitus.
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18
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Affiliation(s)
- Sara Conti
- Mario Negri Institute for Pharmacological Research, Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, via Stezzano, 87-24126 Bergamo, Italy
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19
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Lee TC, Greene-Schloesser D, Payne V, Diz DI, Hsu FC, Kooshki M, Mustafa R, Riddle DR, Zhao W, Chan MD, Robbins ME. Chronic administration of the angiotensin-converting enzyme inhibitor, ramipril, prevents fractionated whole-brain irradiation-induced perirhinal cortex-dependent cognitive impairment. Radiat Res 2012; 178:46-56. [PMID: 22687052 PMCID: PMC3422865 DOI: 10.1667/rr2731.1] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2023]
Abstract
We hypothesized that chronic administration of the angiotensin-converting enzyme inhibitor, ramipril, to young adult male rats would prevent/ameliorate fractionated whole-brain irradiation-induced perirhinal cortex-dependent cognitive impairment. Eighty 12-14-week-old young adult male Fischer 344 rats received either: (1) sham irradiation, (2) 40 Gy of fractionated whole-brain irradiation delivered as two 5 Gy fractions/week for 4 weeks, (3) sham irradiation plus continuous administration of 15 mg/L of ramipril in the drinking water starting 3 days before irradiation, or (4) fractionated whole-brain irradiation plus ramipril. Cognitive function was assessed using a perirhinal cortex-dependent version of the novel object recognition task 26 weeks after irradiation. Microglial activation was determined in the perirhinal cortex and the dentate gyrus of the hippocampus 28 weeks after irradiation using the ED1 antibody. Neurogenesis was assessed in the granular cell layer and subgranular zones of the dentate gyrus using a doublecortin antibody. Fractionated whole-brain irradiation led to: (1) a significant impairment in perirhinal cortex-dependent cognitive function, (2) a significant increase in activated microglia in the dentate gyrus but not in the perirhinal cortex, and (3) a significant decrease in neurogenesis. Continuous administration of ramipril before, during, and after irradiation prevented the fractionated whole-brain irradiation-induced changes in perirhinal cortex-dependent cognitive function, as well as in microglial activation in the dentate gyrus. Thus, as hypothesized, continuous administration of the angiotensin-converting enzyme inhibitor, ramipril, can prevent the fractionated whole-brain irradiation-induced impairment in perirhinal cortex-dependent cognitive function.
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Affiliation(s)
- Tammy C Lee
- Department of Molecular Medicine and Translational Science, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USA
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20
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Rodriguez R, Viscarra JA, Minas JN, Nakano D, Nishiyama A, Ortiz RM. Angiotensin receptor blockade increases pancreatic insulin secretion and decreases glucose intolerance during glucose supplementation in a model of metabolic syndrome. Endocrinology 2012; 153:1684-95. [PMID: 22355070 PMCID: PMC3320242 DOI: 10.1210/en.2011-1885] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Renin-angiotensin system blockade improves glucose intolerance and insulin resistance, which contribute to the development of metabolic syndrome. However, the contribution of impaired insulin secretion to the pathogenesis of metabolic syndrome is not well defined. To assess the contributions of angiotensin receptor type 1 (AT₁) activation and high glucose intake on pancreatic function and their effects on insulin signaling in skeletal muscle and adipose tissue, an oral glucose tolerance test (oGTT) was performed in five groups (n = 10/group) of rats: 1) lean strain-control 2) obese Otsuka Long-Evans Tokushima Fatty (OLETF), 3) OLETF + angiotensin receptor blocker (ARB; 10 mg/kg · d olmesartan for 6 wk; OLETF ARB), 4) OLETF + 5% glucose water (HG) for 6 wk (OLETF HG), and 5) OLETF + HG + ARB (OLETF HG/ARB). The glucose response to the oGTT increased 58% in OLETF compared with lean-strain control, whereas glucose supplementation increased it an additional 26%. Blockade of angiotensin receptor reduced the oGTT response 19% in the ARB-treated groups and increased pancreatic insulin secretion 64 and 113% in OLETF ARB and OLETF HG/ARB, respectively. ARB treatment in OLETF ARB and OLETF HG/ARB did not have an effect on insulin signaling proteins in skeletal muscle; however, it reduced pancreatic AT₁ protein expression 20 and 27%, increased pancreatic glucagon-like peptide-1 (GLP-1) receptor protein expression 41 and 88%, respectively, and increased fasting plasma GLP-1 approximately 2.5-fold in OLETF ARB. The results suggest that improvement of glucose intolerance is independent of an improvement in muscle insulin signaling, but rather by improved glucose-stimulated insulin secretion associated with decreased pancreatic AT₁ activation and increased GLP-1 signaling.
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MESH Headings
- Adipose Tissue/drug effects
- Adipose Tissue/metabolism
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Animals
- Blood Pressure/drug effects
- Dietary Supplements
- Disease Models, Animal
- Glucagon-Like Peptide-1 Receptor
- Glucose/administration & dosage
- Glucose/pharmacology
- Glucose Intolerance/metabolism
- Glucose Intolerance/prevention & control
- Insulin/metabolism
- Leptin/blood
- Male
- Metabolic Syndrome/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Pancreas/metabolism
- Rats
- Rats, Inbred OLETF
- Rats, Inbred Strains
- Receptor, Angiotensin, Type 1/drug effects
- Receptor, Angiotensin, Type 1/metabolism
- Receptors, Glucagon/metabolism
- Triglycerides/blood
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Affiliation(s)
- Ruben Rodriguez
- School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California 95343, USA
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21
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Gwathmey TM, Alzayadneh EM, Pendergrass KD, Chappell MC. Novel roles of nuclear angiotensin receptors and signaling mechanisms. Am J Physiol Regul Integr Comp Physiol 2011; 302:R518-30. [PMID: 22170620 DOI: 10.1152/ajpregu.00525.2011] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The renin-angiotensin system (RAS) constitutes an important hormonal system in the physiological regulation of blood pressure. The dysregulation of the RAS is considered a major influence in the development and progression of cardiovascular disease and other pathologies. Indeed, experimental and clinical evidence indicates that blockade of this system with angiotensin-converting enzyme (ACE) inhibitors or angiotensin type 1 receptor (AT1R) antagonists is an effective therapy to attenuate hypertension and diabetic renal injury, and to improve heart failure. Originally defined as a circulating system, multiple tissues express a complete RAS, and compelling evidence now favors an intracellular system involved in cell signaling and function. Within the kidney, intracellular expression of the three predominant ANG receptor subtypes is evident in the nuclear compartment. The ANG type 1 receptor (AT1R) is coupled to the generation of reactive oxygen species (ROS) through the activation of phosphoinositol-3 kinase (PI3K) and PKC. In contrast, both ANG type 2 (AT2R) and ANG-(1-7) (AT7R) receptors stimulate nitric oxide (NO) formation, which may involve nuclear endothelial NO synthase (eNOS). Moreover, blockade of either ACE2-the enzyme that converts ANG II to ANG-(1-7)-or the AT7 receptor exacerbates the ANG II-ROS response on renal nuclei. Finally, in a model of fetal programmed hypertension, the nuclear ROS response to ANG II is enhanced, while both AT2 and AT7 stimulation of NO is attenuated, suggesting that an imbalance in the intracellular RAS may contribute to the development of programming events. We conclude that a functional intracellular or nuclear RAS may have important implications in the therapeutic approaches to cardiovascular disease.
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Affiliation(s)
- TanYa M Gwathmey
- The Hypertension and Vascular Research Center, Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1032, USA
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22
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Abstract
The aging process affects all organs, including the kidneys. As part of this process, progressive scarring and a measurable decline in renal function occur in most people over time. The improved understanding of the processes that can lead to and/or hasten scarring and loss of renal function over time parallels advances in our understanding of the aging process. Clinical factors, including hypertension, diabetes mellitus, obesity, abnormal lipid levels and vitamin D deficiency, have been associated with increasing renal sclerosis with age. In addition, tissue factors such as angiotensin II, advanced glycation end products, oxidative stress and Klotho are associated with renal aging. These associations and possible interventions, including the control of blood pressure, blood sugar, weight, diet and calorie restriction might make renal aging more preventable than inevitable.
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23
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Gilliam-Davis S, Gallagher PE, Payne VS, Kasper SO, Tommasi EN, Westwood BM, Robbins ME, Chappell MC, Diz DI. Long-term systemic angiotensin II type 1 receptor blockade regulates mRNA expression of dorsomedial medulla renin-angiotensin system components. Physiol Genomics 2011; 43:829-35. [PMID: 21540301 DOI: 10.1152/physiolgenomics.00167.2010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In Fischer 344 (F344) rats, renin-angiotensin system (RAS) blockade for 1 yr with the angiotensin II type 1 (AT(1)) receptor blocker L-158,809 prevents age-related impairments in metabolic function, similar to transgenic rats with low glial angiotensinogen (Aogen). Brain RAS regulation may contribute to the benefits of long-term systemic AT(1) antagonism. We assessed the mRNA of RAS components in the dorsomedial medulla of F344 rats at 3 (young; n = 8) or 15 mo of age (old; n = 7) and in rats treated from 3 to 15 mo of age with 20 mg/l of the AT(1) receptor antagonist L-158,809 (Old+L; n = 6). Aogen and renin mRNA were lower in the young compared with old group. Angiotensin-converting enzyme (ACE) mRNA was lower in the old and Old+L compared with the young group. ACE2 and neprilysin expression were significantly higher in Old+L compared with young or old rats. AT(1b), AT(2), and Mas receptor mRNA were higher with treatment. Leptin receptor mRNA was lower in the old rats and this was prevented by L-158,809 treatment. Dual-specificity phosphatase 1 (DUSP1) mRNA was highest in the Old+L group. Aggregate correlate summation revealed a positive relationship for Mas receptor mRNA with food intake. The findings provide evidence for regulation of dorsomedial medullary renin and Aogen mRNA during aging. Long-term AT(1) receptor blockade increases the mRNA of the enzymes ACE2 and neprilysin and the MAS receptor, which could potentially shift the balance from ANG II to ANG-(1-7) and prevent age-related declines in the leptin receptor and its signaling pathway.
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Affiliation(s)
- Shea Gilliam-Davis
- The Hypertension & Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1032, USA
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Arnold AC, Shaltout HA, Gilliam-Davis S, Kock ND, Diz DI. Autonomic control of the heart is altered in Sprague-Dawley rats with spontaneous hydronephrosis. Am J Physiol Heart Circ Physiol 2011; 300:H2206-13. [PMID: 21460193 DOI: 10.1152/ajpheart.01263.2010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The renal medulla plays an important role in cardiovascular regulation, through interactions with the autonomic nervous system. Hydronephrosis is characterized by substantial loss of renal medullary tissue. However, whether alterations in autonomic control of the heart are observed in this condition is unknown. Thus we assessed resting hemodynamics and baroreflex sensitivity (BRS) for control of heart rate in urethane/chloralose-anesthetized Sprague-Dawley rats with normal or hydronephrotic kidneys. While resting arterial pressure was similar, heart rate was higher in rats with hydronephrosis (290 ± 12 normal vs. 344 ± 11 mild/moderate vs. 355 ± 13 beats/min severe; P < 0.05). The evoked BRS to increases, but not decreases, in pressure was lower in hydronephrotic rats (1.06 ± 0.06 normal vs. 0.72 ± 0.10 mild/moderate vs. 0.63 ± 0.07 ms/mmHg severe; P < 0.05). Spectral analysis methods confirmed reduced parasympathetic function in hydronephrosis, with no differences in measures of indirect sympathetic activity among conditions. As a secondary aim, we investigated whether autonomic dysfunction in hydronephrosis is associated with activation of the renin-angiotensin system (RAS). There were no differences in circulating angiotensin peptides among conditions, suggesting that the impaired autonomic function in hydronephrosis is independent of peripheral RAS activation. A possible site for angiotensin II-mediated BRS impairment is the solitary tract nucleus (NTS). In normal and mild/moderate hydronephrotic rats, NTS administration of the angiotensin II type 1 receptor antagonist candesartan significantly improved the BRS, suggesting that angiotensin II provides tonic suppression to the baroreflex. In contrast, angiotensin II blockade produced no significant effect in severe hydronephrosis, indicating that at least within the NTS baroreflex suppression in these animals is independent of angiotensin II.
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Affiliation(s)
- Amy C Arnold
- The Hypertension & Vascular Research Center, Wake Forest Univ. School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1032, USA.
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25
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Thornton SN. Angiotensin inhibition and longevity: a question of hydration. Pflugers Arch 2010; 461:317-24. [PMID: 21165644 DOI: 10.1007/s00424-010-0911-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 11/25/2010] [Accepted: 11/29/2010] [Indexed: 01/07/2023]
Abstract
With the advancement of medical and investigative science, it is somewhat surprising that although it is possible to stabilise medical patients with hypertension and the associated kidney dysfunction, obesity, diabetes and even cancer, there is still no clear method of significantly reducing these chronic disease pathologies, and thus, extending life expectancy. There is one hormone common to these pathologies, the antagonism of which goes some way to clinical improvements, and this is angiotensin, which is released during hypovolaemia. Angiotensin antagonists are used to treat many of these pathologies, and it has been shown in the obesity literature that angiotensin antagonists decrease weight, but also increase the drinking of water. Increased cellular hydration, and hence, improved mitochondrial metabolism could be one of the mechanisms for the reduction in weight seen in these studies, as well as for reducing the other pathologies, all showing metabolic dysfunction. It appears that the application of straightforward physiological regulation might be an appropriate medical approach to the prevention of hypertension, kidney disease, obesity, diabetes and cancer, and thus, to an increased life expectancy.
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26
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Robbins ME, Zhao W, Garcia-Espinosa MA, Diz DI. Renin-angiotensin system blockers and modulation of radiation-induced brain injury. Curr Drug Targets 2010; 11:1413-22. [PMID: 20583976 PMCID: PMC3068470 DOI: 10.2174/1389450111009011413] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2009] [Accepted: 04/05/2010] [Indexed: 01/05/2023]
Abstract
Radiation-induced brain injury remains a major cause of morbidity in cancer patients with primary or metastatic brain tumors. Approximately 200,000 individuals/year are treated with fractionated partial or whole-brain irradiation, and > half will survive long enough (≤6 months) to develop radiation-induced brain injury, including cognitive impairment. Although short-term treatments have shown efficacy, no long-term treatments or preventive approaches are presently available for modulating radiation-induced brain injury. Based on previous preclinical studies clearly demonstrating that renin-angiotensin system (RAS) blockers can modulate radiation-induced late effects in the kidney and lung, we and others hypothesized that RAS blockade would similarly modulate radiation-induced brain injury. Indeed, studies in the last 5 years have shown that both angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor antagonists (AT(1)RAs) can prevent/ameliorate radiation-induced brain injury, including cognitive impairment, in the rat. The mechanistic basis for this RAS blocker-mediated effect remains the subject of ongoing investigations. Putative mechanisms include, i] blockade of Ang II/NADPH oxidase-mediated oxidative stress and neuroinflammation, and ii] a change in the balance of angiotensin (Ang) peptides from the pro-inflammatory and pro-oxidative Ang II to the anti-inflammatory and anti-oxidative Ang-1-7). However, given that both ACEIs and AT(1)RAs are 1] well-tolerated drugs routinely prescribed for hypertension, 2] exhibit some antitumor properties, and 3] can prevent/ameliorate radiation-induced brain injury, they appear to be ideal drugs for future clinical trials, offering the promise of improving the quality of life of brain tumor patients receiving brain irradiation.
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Affiliation(s)
- M E Robbins
- Department of Radiation Oncology, Brain Tumor Center of Excellence, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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de Cavanagh EMV, Inserra F, Ferder L. Angiotensin II blockade: a strategy to slow ageing by protecting mitochondria? Cardiovasc Res 2010; 89:31-40. [PMID: 20819950 DOI: 10.1093/cvr/cvq285] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Protein and lipid oxidation-mainly by mitochondrial reactive oxygen species (mtROS)-was proposed as a crucial determinant of health and lifespan. Angiotensin II (Ang II) enhances ROS production by activating NAD(P)H oxidase and uncoupling endothelial nitric oxide synthase (NOS). Ang II also stimulates mtROS production, which depresses mitochondrial energy metabolism. In rodents, renin-angiotensin system blockade (RAS blockade) increases survival and prevents age-associated changes. RAS blockade reduces mtROS and enhances mitochondrial content and function. This suggests that Ang II contributes to the ageing process by prompting mitochondrial dysfunction. Since Ang II is a pleiotropic peptide, the age-protecting effects of RAS blockade are expected to involve a variety of other mechanisms. Caloric restriction (CR)-an age-retarding intervention in humans and animals-and RAS blockade display a number of converging effects, i.e. they delay the manifestations of hypertension, diabetes, nephropathy, cardiovascular disease, and cancer; increase body temperature; reduce body weight, plasma glucose, insulin, and insulin-like growth factor-1; ameliorate insulin sensitivity; lower protein, lipid, and DNA oxidation, and mitochondrial H(2)O(2) production; and increase uncoupling protein-2 and sirtuin expression. A number of these overlapping effects involve changes in mitochondrial function. In CR, peroxisome proliferator-activated receptors (PPARs) seem to contribute to age-retardation partly by regulating mitochondrial function. RAS inhibition up-regulates PPARs; therefore, it is feasible that PPAR modulation is pivotal for mitochondrial protection by RAS blockade during rodent ageing. Other potential mechanisms that may underlie RAS blockade's mitochondrial benefits are TGF-β down-regulation and up-regulation of Klotho and sirtuins. In conclusion, the available data suggest that RAS blockade deserves further research efforts to establish its role as a potential tool to mitigate the growing problem of age-associated chronic disease.
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Affiliation(s)
- Elena M V de Cavanagh
- Center of Hypertension, Cardiology Department, Austral University Hospital, Derqui, Argentina
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Yanes LL, Romero DG, Iliescu R, Zhang H, Davis D, Reckelhoff JF. Postmenopausal hypertension: role of the Renin-Angiotensin system. Hypertension 2010; 56:359-63. [PMID: 20679182 DOI: 10.1161/hypertensionaha.110.152975] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
After menopause, blood pressure increases in women. However, the underlying mechanisms responsible for postmenopausal hypertension are not completely understood. This study was conducted to determine the role that the renin-angiotensin system (RAS) plays in post-menopausal hypertension. Post-estrous cycling (postmenopausal) spontaneously hypertensive rats or young female controls were treated with losartan, an angiotensin (Ang) II type 1 receptor blocker, for 25 days. Mean arterial pressure was recorded continuously by radiotelemetry. Losartan significantly decreased blood pressure in postmenopausal rats and young female controls but failed to normalize blood pressure in postmenopausal rats to levels found in young controls. Plasma renin activity and plasma angiotensinogen were significantly elevated, and intrarenal Ang II type 1 receptor and renin mRNA expression were significantly downregulated in postmenopausal rats. Therefore, RAS only partially contributes to hypertension in postcycling spontaneously hypertensive rats, whereas hypertension in young females is mediated mainly by the RAS. The data suggest that other mechanisms besides activation of the RAS are likely involved in postmenopausal hypertension.
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Affiliation(s)
- Licy L Yanes
- Department of Physiology and Biophysics, University of Mississippi Medical Center, 2500 N State Street, Jackson, MS 39216-4505, USA
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Weinstein JR, Anderson S. The aging kidney: physiological changes. Adv Chronic Kidney Dis 2010; 17:302-7. [PMID: 20610357 DOI: 10.1053/j.ackd.2010.05.002] [Citation(s) in RCA: 376] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 05/03/2010] [Accepted: 05/06/2010] [Indexed: 12/28/2022]
Abstract
Age-associated loss of kidney function has been recognized for decades. With aging, many subjects exhibit progressive decreases in glomerular filtration rate and renal blood flow, with wide variability among individuals. The fall in glomerular filtration rate is because of reductions in the glomerular capillary plasma flow rate and the glomerular capillary ultrafiltration coefficient. In addition, a primary reduction in afferent arteriolar resistance is associated with an increase in glomerular capillary hydraulic pressure. These hemodynamic changes occur in concert with structural changes, including loss of renal mass; hyalinization of afferent arterioles and in some cases, development of aglomerular arterioles; an increase in the percentage of sclerotic glomeruli; and tubulointerstitial fibrosis. Aging is associated with altered activity and responsiveness to vasoactive stimuli, such that responses to vasoconstrictor stimuli are enhanced, whereas vasodilatory responses are impaired. Changes in the activity of the renin-angiotensin and nitric oxide systems appear to be particularly important, as is the modulating effect of gender. These changes may predispose the older kidney to acute kidney injury, including normotensive ischemic nephropathy, as well as progressive chronic kidney disease.
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Direct renin inhibition improved insulin resistance and adipose tissue dysfunction in type 2 diabetic KK-Ay mice. J Hypertens 2010; 28:1471-81. [DOI: 10.1097/hjh.0b013e32833bc420] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Conner KR, Payne VS, Forbes ME, Robbins ME, Riddle DR. Effects of the AT1 receptor antagonist L-158,809 on microglia and neurogenesis after fractionated whole-brain irradiation. Radiat Res 2010; 173:49-61. [PMID: 20041759 DOI: 10.1667/rr1821.1] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cognitive dysfunction develops in approximately 50% of patients who receive fractionated whole-brain irradiation and survive 6 months or more. The mechanisms underlying these deficits are unknown. A recent study demonstrated that treatment with the angiotensin II type 1 receptor antagonist (AT(1)RA) L-158,809 before, during and after fractionated whole-brain irradiation prevents or ameliorates radiation-induced cognitive deficits in adult rats. Given that (1) AT(1)RAs may function as anti-inflammatory drugs, (2) inflammation is thought to contribute to radiation injury, and (3) radiation-induced inflammation alters progenitor cell populations, we tested whether the cognitive benefits of L-158,809 treatment were associated with amelioration of the sustained neuroinflammation and changes in neurogenesis that are induced by fractionated whole-brain irradiation. In rats examined 28 and 54 weeks after irradiation, L-158,809 treatment did not alter the effects of radiation on the number and activation of microglia in the perirhinal cortex and hippocampus, nor did it prevent the radiation-induced decrease in proliferating cells and immature neurons in the hippocampus. These findings suggest that L-158,809 does not prevent or ameliorate radiation-induced cognitive deficits by modulation of chronic inflammatory mechanisms, but rather may reduce radiation-induced changes that occur earlier in the postirradiation period and that lead to cognitive dysfunction.
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Affiliation(s)
- Kelly R Conner
- Program in Neuroscience, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1010, USA
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Arnold AC, Shaltout HA, Gallagher PE, Diz DI. Leptin impairs cardiovagal baroreflex function at the level of the solitary tract nucleus. Hypertension 2009; 54:1001-8. [PMID: 19770402 DOI: 10.1161/hypertensionaha.109.138065] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Circulating leptin is elevated in some forms of obesity-related hypertension, associated with impaired baroreflex function. Leptin receptors are present on vagal afferent fibers and neurons within the solitary tract nucleus, providing an anatomic distribution consistent with baroreflex modulation. Although solitary tract nucleus microinjection of 144 fmol/60 nL of leptin had no significant effect on baroreflex sensitivity for control of the heart rate in urethane/chloralose-anesthetized Sprague-Dawley rats, 500 fmol of leptin impaired baroreflex sensitivity for bradycardia in response to increases in pressure (1.15+/-0.04 versus 0.52+/-0.12 ms/mm Hg; P<0.01). Transgenic ASrAOGEN rats with low brain angiotensinogen have an upregulation of the leptin receptor and p85 alpha mRNA in the dorsal medulla relative to Sprague-Dawley rats. Consistent with these observations, the response to leptin was enhanced in ASrAOGEN rats, because both the 144-fmol (1.46+/-0.08 versus 0.75+/-0.10 ms/mm Hg; P<0.001) and 500-fmol (1.36+/-0.32 versus 0.44+/-0.06 ms/mm Hg; P<0.05) leptin microinjections impaired baroreflex sensitivity. At these doses, leptin microinjection had no effect on resting pressure, heart rate, or the tachycardic response to decreases in pressure in Sprague-Dawley or ASrAOGEN rats. Thus, exogenous leptin at sites within the solitary tract nucleus impairs the baroreflex sensitivity for bradycardia induced by increases in arterial pressure, consistent with a permissive role in mediating increases in arterial pressure. Baroreflex inhibition was enhanced in animals with evidence of increased leptin receptor and relevant signaling pathway mRNA.
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Affiliation(s)
- Amy C Arnold
- Hypertension and Vascular Research Center and Physiology and Pharmacology Department, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1032, USA
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Cassis P, Conti S, Remuzzi G, Benigni A. Angiotensin receptors as determinants of life span. Pflugers Arch 2009; 459:325-32. [DOI: 10.1007/s00424-009-0725-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 08/26/2009] [Indexed: 01/21/2023]
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Robbins ME, Payne V, Tommasi E, Diz DI, Hsu FC, Brown WR, Wheeler KT, Olson J, Zhao W. The AT1 receptor antagonist, L-158,809, prevents or ameliorates fractionated whole-brain irradiation-induced cognitive impairment. Int J Radiat Oncol Biol Phys 2008; 73:499-505. [PMID: 19084353 DOI: 10.1016/j.ijrobp.2008.09.058] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 09/03/2008] [Accepted: 09/28/2008] [Indexed: 11/29/2022]
Abstract
PURPOSE We hypothesized that administration of the angiotensin type 1 (AT1) receptor antagonist, L-158,809, to young adult male rats would prevent or ameliorate fractionated whole-brain irradiation (WBI)-induced cognitive impairment. MATERIALS AND METHODS Groups of 80 young adult male Fischer 344 x Brown Norway (F344xBN) rats, 12-14 weeks old, received either: (1) fractionated WBI; 40 Gy of gamma rays in 4 weeks, 2 fractions/week, (2) sham-irradiation; (3) WBI plus L-158,809 (20 mg/L drinking water) starting 3 days prior, during, and for 14, 28, or 54 weeks postirradiation; and (4) sham-irradiation plus L-158,809 for 14, 28, or 54 weeks postirradiation. An additional group of rats (n = 20) received L-158,809 before, during, and for 5 weeks postirradiation, after which they received normal drinking water up to 28 weeks postirradiation. RESULTS Administration of L-158,809 before, during, and for 28 or 54 weeks after fractionated WBI prevented or ameliorated the radiation-induced cognitive impairment observed 26 and 52 weeks postirradiation. Moreover, giving L-158,809 before, during, and for only 5 weeks postirradiation ameliorated the significant cognitive impairment observed 26 weeks postirradiation. These radiation-induced cognitive impairments occurred without any changes in brain metabolites or gross histologic changes assessed at 28 and 54 weeks postirradiation, respectively. CONCLUSIONS Administering L-158,809 before, during, and after fractionated WBI can prevent or ameliorate the chronic, progressive, cognitive impairment observed in rats at 26 and 52 weeks postirradiation. These findings offer the promise of improving the quality of life for brain tumor patients.
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Affiliation(s)
- Mike E Robbins
- Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
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Affiliation(s)
- Debra I Diz
- Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1032, USA.
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Diz DI, Varagic J, Groban L. Aging and the brain renin-angiotensin system: relevance to age-related decline in cardiac function. Future Cardiol 2008; 4:237-45. [PMID: 19804328 PMCID: PMC2929677 DOI: 10.2217/14796678.4.3.237] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
This article discusses evidence that impairments in control of autonomic outflow mediated by the brain renin-angiotensin system (RAS) contribute to the decline in baroreceptor reflex function and the development of insulin resistance that accompany hypertension and excess salt intake, especially during aging. Imbalances in the regulation of the sympathetic and parasympathetic limbs of the autonomic nervous system observed in older subjects underlie changes in heart-rate variability and play a role in the regulation of overall cardiac function. Age-related alterations in autonomic nervous system function may also explain the age-associated alterations in metabolism. Reduced heart-rate variability is linked to increased mortality in patients with cardiovascular disorders and, coupled with information that is known about local changes in the cardiac and brain RAS during aging, the evidence reveals potential mechanisms for the protective effects of systemic blockade of the RAS against age-related changes that impact the heart.
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Affiliation(s)
- Debra I Diz
- Wake Forest University School of Medicine, The Hypertension & Vascular Research Center, Medical Center Boulevard, Winston-Salem, NC 27157-1032, USA, Tel.: +1 336 716 2150; Fax: +1 336 716 2456;
| | - Jasmina Varagic
- Wake Forest University School of Medicine, The Hypertension & Vascular Research Center, Medical Center Boulevard, Winston-Salem, NC 27157-1032, USA, Tel.: +1 336 716 2738; Fax: +1 336 716 2456;
| | - Leanne Groban
- Wake Forest University School of Medicine, Department of Anesthesiology, Medical Center Boulevard, Winston-Salem, NC 27157-1032, USA, Tel.: +1 336 716 1187; Fax: +1 336 716 8190;
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Mice lacking angiotensin-converting enzyme have increased energy expenditure, with reduced fat mass and improved glucose clearance. Proc Natl Acad Sci U S A 2008; 105:6531-6. [PMID: 18443281 DOI: 10.1073/pnas.0802690105] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In addition to its role in the storage of fat, adipose tissue acts as an endocrine organ, and it contains a functional renin-angiotensin system (RAS). Angiotensin-converting enzyme (ACE) plays a key role in the RAS by converting angiotensin I to the bioactive peptide angiotensin II (Ang II). In the present study, the effect of targeting the RAS in body energy homeostasis and glucose tolerance was determined in homozygous mice in which the gene for ACE had been deleted (ACE(-/-)) and compared with wild-type littermates. Compared with wild-type littermates, ACE(-/-) mice had lower body weight and a lower proportion of body fat, especially in the abdomen. ACE(-/-) mice had greater fed-state total energy expenditure (TEE) and resting energy expenditure (REE) than wild-type littermates. There were pronounced increases in gene expression of enzymes related to lipolysis and fatty acid oxidation (lipoprotein lipase, carnitine palmitoyl transferase, long-chain acetyl CoA dehydrogenase) in the liver of ACE(-/-) mice and also lower plasma leptin. In contrast, no differences were detected in daily food intake, activity, fed-state plasma lipids, or proportion of fat excreted in fecal matter. In conclusion, the reduction in ACE activity is associated with a decreased accumulation of body fat, especially in abdominal fat depots. The decreased body fat in ACE(-/-) mice is independent of food intake and appears to be due to a high energy expenditure related to increased metabolism of fatty acids in the liver, with the additional effect of increased glucose tolerance.
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