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Bhullar SK, Dhalla NS. Adaptive and maladaptive roles of different angiotensin receptors in the development of cardiac hypertrophy and heart failure. Can J Physiol Pharmacol 2024; 102:86-104. [PMID: 37748204 DOI: 10.1139/cjpp-2023-0226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Angiotensin II (Ang II) is formed by the action of angiotensin-converting enzyme (ACE) in the renin-angiotensin system. This hormone is known to induce cardiac hypertrophy and heart failure and its actions are mediated by the interaction of both pro- and antihypertrophic Ang II receptors (AT1R and AT2R). Ang II is also metabolized by ACE 2 to Ang-(1-7), which elicits the activation of Mas receptors (MasR) for inducing antihypertrophic actions. Since heart failure under different pathophysiological situations is preceded by adaptive and maladaptive cardiac hypertrophy, we have reviewed the existing literature to gain some information regarding the roles of AT1R, AT2R, and MasR in both acute and chronic conditions of cardiac hypertrophy. It appears that the activation of AT1R may be involved in the development of adaptive and maladaptive cardiac hypertrophy as well as subsequent heart failure because both ACE inhibitors and AT1R antagonists exert beneficial effects. On the other hand, the activation of both AT2R and MasR may prevent the occurrence of maladaptive cardiac hypertrophy and delay the progression of heart failure, and thus therapy with different activators of these antihypertrophic receptors under chronic pathological stages may prove beneficial. Accordingly, it is suggested that a great deal of effort should be made to develop appropriate activators of both AT2R and MasR for the treatment of heart failure subjects.
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Affiliation(s)
- Sukhwinder K Bhullar
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre and Department of Physiology and Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, Canada
| | - Naranjan S Dhalla
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre and Department of Physiology and Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, Canada
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Issotina Zibrila A, Li Y, Wang Z, Zhao G, Liu H, Leng J, Ahasan Ali M, Ampofo Osei J, Kang YM, Liu J. Acetylcholinesterase inhibition with Pyridostigmine attenuates hypertension and neuroinflammation in the paraventricular nucleus in rat model for Preeclampsia. Int Immunopharmacol 2021; 101:108365. [PMID: 34815190 DOI: 10.1016/j.intimp.2021.108365] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 10/30/2021] [Accepted: 11/09/2021] [Indexed: 11/15/2022]
Abstract
Preeclampsia (PE) is characterized by hypertension, autonomic imbalance and inflammation. The subfornical organ (SFO) reportedly relays peripheral inflammatory mediator's signals to the paraventricular nucleus (PVN), a brain autonomic center shown to mediate hypertension in hypertensive rat but not yet in PE rat models. Additionally, we previously showed that Pyridostigmine (PYR), an acetylcholinesterase inhibitor, attenuated placental inflammation and hypertension in PE models. In this study, we investigated the effect of PYR on the activities of these brain regions in PE model. PYR (20 mg/kg/day) was administered to reduced uterine perfusion pressure (RUPP) Sprague-Dawley rat from gestational day (GD) 14 to GD19. On GD19, the mean arterial pressure (MAP) was recorded and samples were collected for analysis. RUPP rats exhibited increased MAP (P = 0.0025), elevated circulating tumor necrosis factor-α (TNF-α, P = 0.0075), reduced baroreflex sensitivity (BRS), increased neuroinflammatory markers including TNF-α, interleukin-1β (IL-1β), microglial activation (P = 0.0039), oxidative stress and neuronal excitation within the PVN and the SFO. Changes in MAP, in molecular and cellular expression induced by RUPP intervention were improved by PYR. The ability of PYR to attenuate TNF-α mediated central effect was evaluated in TNF-α-infused pregnant rats. TNF-α infusion-promoted neuroinflammation in the PVN and SFO in dams was abolished by PYR. Collectively, our data suggest that PYR improves PE-like symptoms in rat by dampening placental ischemia and TNF-α-promoted inflammation and pro-hypertensive activity in the PVN. This broadens the therapeutical potential of PYR in PE.
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Affiliation(s)
- Abdoulaye Issotina Zibrila
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases, Xi'an 710061, Shaanxi, PR China
| | - Yubei Li
- School of Clinical Medicine, Xi'an Medical University, Xi'an 710021, Shaanxi, PR China
| | - Zheng Wang
- Department of Pharmacology, Xi'an Jiaotong University School of Basic Medical Sciences, Xi'an 710061, Shaanxi, PR China
| | - Gongxiao Zhao
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases, Xi'an 710061, Shaanxi, PR China
| | - Haotian Liu
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases, Xi'an 710061, Shaanxi, PR China
| | - Jing Leng
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases, Xi'an 710061, Shaanxi, PR China
| | - Md Ahasan Ali
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases, Xi'an 710061, Shaanxi, PR China
| | - James Ampofo Osei
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases, Xi'an 710061, Shaanxi, PR China
| | - Yu-Ming Kang
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases, Xi'an 710061, Shaanxi, PR China.
| | - Jinjun Liu
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases, Xi'an 710061, Shaanxi, PR China.
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Parmar HS, Nayak A, Gavel PK, Jha H, Bhagwat S, Sharma R. Cross talk between COVID-19 and breast cancer. Curr Cancer Drug Targets 2021; 21:575-600. [PMID: 33593260 DOI: 10.2174/1568009621666210216102236] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 12/17/2020] [Accepted: 12/26/2020] [Indexed: 01/08/2023]
Abstract
Cancer patients are more susceptible for COVID-19; however, the prevalence of COVID-19 in different types of cancer is still inconsistent and inconclusive. Here, we delineate the intricate relationship between breast cancer and COVID-19. Breast cancer and COVID-19 share involvement of common comorbidities, hormonal signalling pathways, gender differences, rennin-angiotensin system (RAS), angiotensin-converting enzyme-2 (ACE-2), transmembrane protease serine 2 (TMPRSS2) and dipeptidyl peptidase-IV (DPP-IV). We also shed light on the possible effects of therapeutic modalities of COVID-19 on breast cancer outcomes. Briefly, we conclude that breast cancer patients are more susceptible for COVID-19 in comparison with their normal counterparts. Women are more resistant for the occurrence and severity of COVID-19. Increased expression of ACE2 and TMPRSS2 are being correlated with occurrence and severity of COVID-19, but higher expression of ACE2 and lower expression of TMPRSS2 are prognostic markers for overall and disease free survival in breast cancer. The ACE2 inhibitors and ibuprofen therapies for COVID-19 treatment may aggravate the clinical condition of the breast cancer patients through chemo-resistance and metastasis. Most of the available therapeutic modalities for COVID-19 were also found to exert positive effects on breast cancer outcomes. Besides drugs in clinical trend, TMPRSS2 inhibitors, estrogen supplementation, androgen deprivation and DPP-IV inhibitors may also be used to treat breast cancer patients infected with SARS-CoV-2. However, drug-drug interactions suggest that some of the drugs used for the treatment of COVID-19 may modulate the drug metabolism of anticancer therapies which may leads to adverse drug reaction events.
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Affiliation(s)
| | - Aakruti Nayak
- School of Biotechnology, Devi Ahilya University, Indore-452001. M.P. India
| | - Pramod Kumar Gavel
- Department of Chemical Sciences, IIT, Indore, Simrol, Indore. M.P. India
| | - Hemchandra Jha
- Department of Bioscience and Bioengineering, IIT, Simrol, Indore. India
| | | | - Rajesh Sharma
- School of Pharamcy, Devi Ahilya University, Indore-452001., M.P. India
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Abstract
The renin-angiotensin system is an important component of the cardiovascular system. Mounting evidence suggests that the metabolic products of angiotensin I and II - initially thought to be biologically inactive - have key roles in cardiovascular physiology and pathophysiology. This non-canonical axis of the renin-angiotensin system consists of angiotensin 1-7, angiotensin 1-9, angiotensin-converting enzyme 2, the type 2 angiotensin II receptor (AT2R), the proto-oncogene Mas receptor and the Mas-related G protein-coupled receptor member D. Each of these components has been shown to counteract the effects of the classical renin-angiotensin system. This counter-regulatory renin-angiotensin system has a central role in the pathogenesis and development of various cardiovascular diseases and, therefore, represents a potential therapeutic target. In this Review, we provide the latest insights into the complexity and interplay of the components of the non-canonical renin-angiotensin system, and discuss the function and therapeutic potential of targeting this system to treat cardiovascular disease.
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Forrester SJ, Booz GW, Sigmund CD, Coffman TM, Kawai T, Rizzo V, Scalia R, Eguchi S. Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology. Physiol Rev 2018; 98:1627-1738. [PMID: 29873596 DOI: 10.1152/physrev.00038.2017] [Citation(s) in RCA: 614] [Impact Index Per Article: 102.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The renin-angiotensin-aldosterone system plays crucial roles in cardiovascular physiology and pathophysiology. However, many of the signaling mechanisms have been unclear. The angiotensin II (ANG II) type 1 receptor (AT1R) is believed to mediate most functions of ANG II in the system. AT1R utilizes various signal transduction cascades causing hypertension, cardiovascular remodeling, and end organ damage. Moreover, functional cross-talk between AT1R signaling pathways and other signaling pathways have been recognized. Accumulating evidence reveals the complexity of ANG II signal transduction in pathophysiology of the vasculature, heart, kidney, and brain, as well as several pathophysiological features, including inflammation, metabolic dysfunction, and aging. In this review, we provide a comprehensive update of the ANG II receptor signaling events and their functional significances for potential translation into therapeutic strategies. AT1R remains central to the system in mediating physiological and pathophysiological functions of ANG II, and participation of specific signaling pathways becomes much clearer. There are still certain limitations and many controversies, and several noteworthy new concepts require further support. However, it is expected that rigorous translational research of the ANG II signaling pathways including those in large animals and humans will contribute to establishing effective new therapies against various diseases.
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Affiliation(s)
- Steven J Forrester
- Cardiovascular Research Center, Lewis Katz School of Medicine at Temple University , Philadelphia, Pennsylvania ; Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center , Jackson, Mississippi ; Department of Pharmacology, Center for Hypertension Research, Roy J. and Lucille A. Carver College of Medicine, University of Iowa , Iowa City, Iowa ; and Duke-NUS, Singapore and Department of Medicine, Duke University Medical Center , Durham, North Carolina
| | - George W Booz
- Cardiovascular Research Center, Lewis Katz School of Medicine at Temple University , Philadelphia, Pennsylvania ; Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center , Jackson, Mississippi ; Department of Pharmacology, Center for Hypertension Research, Roy J. and Lucille A. Carver College of Medicine, University of Iowa , Iowa City, Iowa ; and Duke-NUS, Singapore and Department of Medicine, Duke University Medical Center , Durham, North Carolina
| | - Curt D Sigmund
- Cardiovascular Research Center, Lewis Katz School of Medicine at Temple University , Philadelphia, Pennsylvania ; Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center , Jackson, Mississippi ; Department of Pharmacology, Center for Hypertension Research, Roy J. and Lucille A. Carver College of Medicine, University of Iowa , Iowa City, Iowa ; and Duke-NUS, Singapore and Department of Medicine, Duke University Medical Center , Durham, North Carolina
| | - Thomas M Coffman
- Cardiovascular Research Center, Lewis Katz School of Medicine at Temple University , Philadelphia, Pennsylvania ; Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center , Jackson, Mississippi ; Department of Pharmacology, Center for Hypertension Research, Roy J. and Lucille A. Carver College of Medicine, University of Iowa , Iowa City, Iowa ; and Duke-NUS, Singapore and Department of Medicine, Duke University Medical Center , Durham, North Carolina
| | - Tatsuo Kawai
- Cardiovascular Research Center, Lewis Katz School of Medicine at Temple University , Philadelphia, Pennsylvania ; Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center , Jackson, Mississippi ; Department of Pharmacology, Center for Hypertension Research, Roy J. and Lucille A. Carver College of Medicine, University of Iowa , Iowa City, Iowa ; and Duke-NUS, Singapore and Department of Medicine, Duke University Medical Center , Durham, North Carolina
| | - Victor Rizzo
- Cardiovascular Research Center, Lewis Katz School of Medicine at Temple University , Philadelphia, Pennsylvania ; Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center , Jackson, Mississippi ; Department of Pharmacology, Center for Hypertension Research, Roy J. and Lucille A. Carver College of Medicine, University of Iowa , Iowa City, Iowa ; and Duke-NUS, Singapore and Department of Medicine, Duke University Medical Center , Durham, North Carolina
| | - Rosario Scalia
- Cardiovascular Research Center, Lewis Katz School of Medicine at Temple University , Philadelphia, Pennsylvania ; Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center , Jackson, Mississippi ; Department of Pharmacology, Center for Hypertension Research, Roy J. and Lucille A. Carver College of Medicine, University of Iowa , Iowa City, Iowa ; and Duke-NUS, Singapore and Department of Medicine, Duke University Medical Center , Durham, North Carolina
| | - Satoru Eguchi
- Cardiovascular Research Center, Lewis Katz School of Medicine at Temple University , Philadelphia, Pennsylvania ; Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center , Jackson, Mississippi ; Department of Pharmacology, Center for Hypertension Research, Roy J. and Lucille A. Carver College of Medicine, University of Iowa , Iowa City, Iowa ; and Duke-NUS, Singapore and Department of Medicine, Duke University Medical Center , Durham, North Carolina
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Santos RAS, Sampaio WO, Alzamora AC, Motta-Santos D, Alenina N, Bader M, Campagnole-Santos MJ. The ACE2/Angiotensin-(1-7)/MAS Axis of the Renin-Angiotensin System: Focus on Angiotensin-(1-7). Physiol Rev 2018; 98:505-553. [PMID: 29351514 PMCID: PMC7203574 DOI: 10.1152/physrev.00023.2016] [Citation(s) in RCA: 681] [Impact Index Per Article: 113.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The renin-angiotensin system (RAS) is a key player in the control of the cardiovascular system and hydroelectrolyte balance, with an influence on organs and functions throughout the body. The classical view of this system saw it as a sequence of many enzymatic steps that culminate in the production of a single biologically active metabolite, the octapeptide angiotensin (ANG) II, by the angiotensin converting enzyme (ACE). The past two decades have revealed new functions for some of the intermediate products, beyond their roles as substrates along the classical route. They may be processed in alternative ways by enzymes such as the ACE homolog ACE2. One effect is to establish a second axis through ACE2/ANG-(1-7)/MAS, whose end point is the metabolite ANG-(1-7). ACE2 and other enzymes can form ANG-(1-7) directly or indirectly from either the decapeptide ANG I or from ANG II. In many cases, this second axis appears to counteract or modulate the effects of the classical axis. ANG-(1-7) itself acts on the receptor MAS to influence a range of mechanisms in the heart, kidney, brain, and other tissues. This review highlights the current knowledge about the roles of ANG-(1-7) in physiology and disease, with particular emphasis on the brain.
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Affiliation(s)
- Robson Augusto Souza Santos
- National Institute of Science and Technology in Nanobiopharmaceutics, Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais , Belo Horizonte , Brazil ; Department of Biological Sciences, Federal University of Ouro Preto , Ouro Preto , Brazil ; Max-Delbrück-Center for Molecular Medicine (MDC), Berlin , Germany ; Berlin Institute of Health (BIH), Berlin , Germany ; Charité - University Medicine, Berlin , Germany ; DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin , Germany ; Institute for Biology, University of Lübeck , Lübeck , Germany
| | - Walkyria Oliveira Sampaio
- National Institute of Science and Technology in Nanobiopharmaceutics, Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais , Belo Horizonte , Brazil ; Department of Biological Sciences, Federal University of Ouro Preto , Ouro Preto , Brazil ; Max-Delbrück-Center for Molecular Medicine (MDC), Berlin , Germany ; Berlin Institute of Health (BIH), Berlin , Germany ; Charité - University Medicine, Berlin , Germany ; DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin , Germany ; Institute for Biology, University of Lübeck , Lübeck , Germany
| | - Andreia C Alzamora
- National Institute of Science and Technology in Nanobiopharmaceutics, Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais , Belo Horizonte , Brazil ; Department of Biological Sciences, Federal University of Ouro Preto , Ouro Preto , Brazil ; Max-Delbrück-Center for Molecular Medicine (MDC), Berlin , Germany ; Berlin Institute of Health (BIH), Berlin , Germany ; Charité - University Medicine, Berlin , Germany ; DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin , Germany ; Institute for Biology, University of Lübeck , Lübeck , Germany
| | - Daisy Motta-Santos
- National Institute of Science and Technology in Nanobiopharmaceutics, Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais , Belo Horizonte , Brazil ; Department of Biological Sciences, Federal University of Ouro Preto , Ouro Preto , Brazil ; Max-Delbrück-Center for Molecular Medicine (MDC), Berlin , Germany ; Berlin Institute of Health (BIH), Berlin , Germany ; Charité - University Medicine, Berlin , Germany ; DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin , Germany ; Institute for Biology, University of Lübeck , Lübeck , Germany
| | - Natalia Alenina
- National Institute of Science and Technology in Nanobiopharmaceutics, Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais , Belo Horizonte , Brazil ; Department of Biological Sciences, Federal University of Ouro Preto , Ouro Preto , Brazil ; Max-Delbrück-Center for Molecular Medicine (MDC), Berlin , Germany ; Berlin Institute of Health (BIH), Berlin , Germany ; Charité - University Medicine, Berlin , Germany ; DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin , Germany ; Institute for Biology, University of Lübeck , Lübeck , Germany
| | - Michael Bader
- National Institute of Science and Technology in Nanobiopharmaceutics, Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais , Belo Horizonte , Brazil ; Department of Biological Sciences, Federal University of Ouro Preto , Ouro Preto , Brazil ; Max-Delbrück-Center for Molecular Medicine (MDC), Berlin , Germany ; Berlin Institute of Health (BIH), Berlin , Germany ; Charité - University Medicine, Berlin , Germany ; DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin , Germany ; Institute for Biology, University of Lübeck , Lübeck , Germany
| | - Maria Jose Campagnole-Santos
- National Institute of Science and Technology in Nanobiopharmaceutics, Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais , Belo Horizonte , Brazil ; Department of Biological Sciences, Federal University of Ouro Preto , Ouro Preto , Brazil ; Max-Delbrück-Center for Molecular Medicine (MDC), Berlin , Germany ; Berlin Institute of Health (BIH), Berlin , Germany ; Charité - University Medicine, Berlin , Germany ; DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin , Germany ; Institute for Biology, University of Lübeck , Lübeck , Germany
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7
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Schaich CL, Grabenauer M, Thomas BF, Shaltout HA, Gallagher PE, Howlett AC, Diz DI. Medullary Endocannabinoids Contribute to the Differential Resting Baroreflex Sensitivity in Rats with Altered Brain Renin-Angiotensin System Expression. Front Physiol 2016; 7:207. [PMID: 27375489 PMCID: PMC4899471 DOI: 10.3389/fphys.2016.00207] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 05/22/2016] [Indexed: 11/13/2022] Open
Abstract
CB1 cannabinoid receptors are expressed on vagal afferent fibers and neurons within the solitary tract nucleus (NTS), providing anatomical evidence for their role in arterial baroreflex modulation. To better understand the relationship between the brain renin-angiotensin system (RAS) and endocannabinoid expression within the NTS, we measured dorsal medullary endocannabinoid tissue content and the effects of CB1 receptor blockade at this brain site on cardiac baroreflex sensitivity (BRS) in ASrAOGEN rats with low glial angiotensinogen, normal Sprague-Dawley rats and (mRen2)27 rats with upregulated brain RAS expression. Mass spectrometry revealed higher levels of the endocannabinoid 2-arachidonoylglycerol in (mRen2)27 compared to ASrAOGEN rats (2.70 ± 0.28 vs. 1.17 ± 0.09 ng/mg tissue; P < 0.01), while Sprague-Dawley rats had intermediate content (1.85 ± 0.27 ng/mg tissue). Microinjection of the CB1receptor antagonist SR141716A (36 pmol) into the NTS did not change cardiac BRS in anesthetized Sprague-Dawley rats (1.04 ± 0.05 ms/mmHg baseline vs. 1.17 ± 0.11 ms/mmHg after 10 min). However, SR141716A in (mRen2)27 rats dose-dependently improved BRS in this strain: 0.36 pmol of SR141716A increased BRS from 0.43 ± 0.03 to 0.71 ± 0.04 ms/mmHg (P < 0.001), and 36 pmol of SR141716A increased BRS from 0.47 ± 0.02 to 0.94 ± 0.10 ms/mmHg (P < 0.01). In contrast, 0.36 pmol (1.50 ± 0.12 vs. 0.86 ± 0.08 ms/mmHg; P < 0.05) and 36 pmol (1.38 ± 0.16 vs. 0.46 ± 0.003 ms/mmHg; P < 0.01) of SR141716A significantly reduced BRS in ASrAOGEN rats. These observations reveal differential dose-related effects of the brain endocannabinoid system that influence cardiovagal BRS in animals with genetic alterations in the brain RAS.
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Affiliation(s)
- Chris L Schaich
- Department of Physiology and Pharmacology and Hypertension and Vascular Research Center, Wake Forest School of Medicine Winston-Salem, NC, USA
| | - Megan Grabenauer
- Department of Physiology and Pharmacology and Hypertension and Vascular Research Center, Wake Forest School of MedicineWinston-Salem, NC, USA; Analytical Chemistry and Pharmaceutics, RTI InternationalResearch Triangle Park, NC, USA
| | - Brian F Thomas
- Department of Physiology and Pharmacology and Hypertension and Vascular Research Center, Wake Forest School of MedicineWinston-Salem, NC, USA; Analytical Chemistry and Pharmaceutics, RTI InternationalResearch Triangle Park, NC, USA
| | - Hossam A Shaltout
- Department of Physiology and Pharmacology and Hypertension and Vascular Research Center, Wake Forest School of MedicineWinston-Salem, NC, USA; Department of Obstetrics and Gynecology, Wake Forest School of MedicineWinston-Salem, NC, USA
| | - Patricia E Gallagher
- Department of Physiology and Pharmacology and Hypertension and Vascular Research Center, Wake Forest School of Medicine Winston-Salem, NC, USA
| | - Allyn C Howlett
- Department of Physiology and Pharmacology and Hypertension and Vascular Research Center, Wake Forest School of Medicine Winston-Salem, NC, USA
| | - Debra I Diz
- Department of Physiology and Pharmacology and Hypertension and Vascular Research Center, Wake Forest School of Medicine Winston-Salem, NC, USA
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Alterations in the Medullary Endocannabinoid System Contribute to Age-related Impairment of Baroreflex Sensitivity. J Cardiovasc Pharmacol 2016; 65:473-9. [PMID: 25636077 DOI: 10.1097/fjc.0000000000000216] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
As they age, Sprague-Dawley (SD) rats develop elevated systolic blood pressure associated with impaired baroreflex sensitivity (BRS) for control of heart rate. We previously demonstrated in young hypertensive (mRen2)27 rats that impaired BRS is restored by CB1 cannabinoid receptor blockade in the solitary tract nucleus (NTS), consistent with elevated content of the endocannabinoid 2-arachidonoylglycerol (2-AG) in dorsal medulla relative to normotensive SD rats. There is no effect of CB1 receptor blockade in young SD rats. We now report in older SD rats that dorsal medullary 2-AG levels are 2-fold higher at 70 versus 15 weeks of age (4.22 ± 0.61 vs. 1.93 ± 0.22 ng/mg tissue; P < 0.05). Furthermore, relative expression of CB1 receptor messenger RNA is significantly lower in aged rats, whereas CB2 receptor messenger RNA is significantly higher. In contrast to young adult SD rats, microinjection of the CB1 receptor antagonist SR141716A (36 pmole) into the NTS of older SD rats normalized BRS in animals exhibiting impaired baseline BRS (0.56 ± 0.06 baseline vs. 1.06 ± 0.05 ms/mm Hg after 60 minutes; P < 0.05). Therefore, this study provides evidence for alterations in the endocannabinoid system within the NTS of older SD rats that contribute to age-related impairment of BRS.
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9
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Exercise Training Improves the Altered Renin-Angiotensin System in the Rostral Ventrolateral Medulla of Hypertensive Rats. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:7413963. [PMID: 26881037 PMCID: PMC4736418 DOI: 10.1155/2016/7413963] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Revised: 11/10/2015] [Accepted: 11/17/2015] [Indexed: 01/25/2023]
Abstract
The imbalance between angiotensin II (Ang II) and angiotensin 1-7 (Ang 1-7) in the brain has been reported to contribute to cardiovascular dysfunction in hypertension. Exercise training (ExT) is beneficial to hypertension and the mechanism is unclear. This study was aimed to determine if ExT improves hypertension via adjusting renin angiotensin system in cardiovascular centers including the rostral ventrolateral medulla (RVLM). Spontaneously hypertensive rats (SHR, 8 weeks old) were subjected to low-intensity ExT or kept sedentary (Sed) for 12 weeks. Blood pressure elevation coupled with increase in age was significantly decreased in SHR received ExT compared with Sed. The results in vivo showed that ExT significantly reduced or increased the cardiovascular responses to central application of sarthran (antagonist of Ang II) or A779 (antagonist of Ang 1-7), respectively. The protein expression of the Ang II acting receptor AT1R and the Ang 1-7 acting receptor Mas in the RVLM was significantly reduced and elevated in SHR following ExT, respectively. Moreover, production of reactive oxygen species in the RVLM was significantly decreased in SHR following ExT. The current data suggest that ExT improves hypertension via improving the balance of Ang II and Ang 1-7 and antioxidative stress at the level of RVLM.
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Coble JP, Grobe JL, Johnson AK, Sigmund CD. Mechanisms of brain renin angiotensin system-induced drinking and blood pressure: importance of the subfornical organ. Am J Physiol Regul Integr Comp Physiol 2014; 308:R238-49. [PMID: 25519738 DOI: 10.1152/ajpregu.00486.2014] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is critical for cells to maintain a homeostatic balance of water and electrolytes because disturbances can disrupt cellular function, which can lead to profound effects on the physiology of an organism. Dehydration can be classified as either intra- or extracellular, and different mechanisms have developed to restore homeostasis in response to each. Whereas the renin-angiotensin system (RAS) is important for restoring homeostasis after dehydration, the pathways mediating the responses to intra- and extracellular dehydration may differ. Thirst responses mediated through the angiotensin type 1 receptor (AT1R) and angiotensin type 2 receptors (AT2R) respond to extracellular dehydration and intracellular dehydration, respectively. Intracellular signaling factors, such as protein kinase C (PKC), reactive oxygen species (ROS), and the mitogen-activated protein (MAP) kinase pathway, mediate the effects of central angiotensin II (ANG II). Experimental evidence also demonstrates the importance of the subfornical organ (SFO) in mediating some of the fluid intake effects of central ANG II. The purpose of this review is to highlight the importance of the SFO in mediating fluid intake responses to dehydration and ANG II.
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Affiliation(s)
| | - Justin L Grobe
- Department of Pharmacology, Center for Hypertension Research, Roy J. and Lucille Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | | | - Curt D Sigmund
- Department of Pharmacology, Center for Hypertension Research, Roy J. and Lucille Carver College of Medicine, University of Iowa, Iowa City, Iowa
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Arnold AC, Diz DI. Endogenous leptin contributes to baroreflex suppression within the solitary tract nucleus of aged rats. Am J Physiol Heart Circ Physiol 2014; 307:H1539-46. [PMID: 25260611 DOI: 10.1152/ajpheart.00282.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The decline in cardiovagal baroreflex function that occurs with aging is accompanied by an increase in circulating leptin levels. Our previous studies showed that exogenous leptin impairs the baroreflex sensitivity for control of heart rate in younger rats, but the contribution of this hormone to baroreflex dysfunction during aging is unknown. Thus we assessed the effect of bilateral leptin microinjection (500 fmol/60 nl) within the solitary tract nucleus (NTS) on the baroreflex sensitivity in older (66 ± 2 wk of age) urethane/chloralose anesthetized Sprague-Dawley rats with elevated circulating leptin levels. In contrast to the 63% reduction observed in younger rats, leptin did not alter the baroreflex sensitivity for bradycardia evoked by phenylephrine in older rats (0.76 ± 0.19 baseline vs. 0.71 ± 0.15 ms/mmHg after leptin; P = 0.806). We hypothesized that this loss of sensitivity reflected endogenous suppression of the baroreflex by elevated leptin, rather than cardiovascular resistance to the peptide. Indeed, NTS administration of a leptin receptor antagonist (75 pmol/120 nl) improved the baroreflex sensitivity for bradycardia in older rats (0.73 ± 0.13 baseline vs. 1.19 ± 0.26 at 10 min vs. 1.87 ± 0.32 at 60 min vs. 1.22 ± 0.54 ms/mmHg at 120 min; P = 0.002), with no effect in younger rats. There was no effect of the leptin antagonist on the baroreflex sensitivity for tachycardia, responses to cardiac vagal chemosensitive fiber activation, or resting hemodynamics in older rats. These findings suggest that the actions of endogenous leptin within the NTS, either produced locally or derived from the circulation, contribute to baroreflex suppression during aging.
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Affiliation(s)
- Amy C Arnold
- Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina
| | - Debra I Diz
- Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina
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O'Callaghan EL, Choong YT, Jancovski N, Allen AM. Central angiotensinergic mechanisms associated with hypertension. Auton Neurosci 2013; 175:85-92. [PMID: 23466041 DOI: 10.1016/j.autneu.2013.01.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 01/23/2013] [Accepted: 01/23/2013] [Indexed: 12/20/2022]
Abstract
Following its generation by both systemic and tissue-based renin-angiotensin systems, angiotensin II interacts with specific, G-protein coupled receptors to modulate multiple physiological systems, including the cardiovascular system. Genetic models in which the different components of the renin-angiotensin system have been deleted show large changes in resting blood pressure. Interruption of the generation of angiotensin II, or its interaction with these receptors, decreases blood pressure in hypertensive humans and experimental animal models of hypertension. Whilst the interaction of angiotensin II with the kidney is pivotal in this modulation of blood pressure, an involvement of the system in other tissues is important. Both systemic angiotensins, acting via the blood-brain barrier deficient circumventricular organs, and centrally-generated angiotensin modulate cardiovascular control by regulating fluid and electrolyte ingestion, autonomic activity and neuroendocrine function. This review discusses the pathways in the brain that are involved in this regulation of blood pressure as well as examining the sites in which altered angiotensin function might contribute to the development and maintenance of high blood pressure.
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Affiliation(s)
- Erin L O'Callaghan
- Department of Physiology, University of Melbourne, Vic., 3010, Australia
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The brain Renin-Angiotensin system and mitochondrial function: influence on blood pressure and baroreflex in transgenic rat strains. Int J Hypertens 2013; 2013:136028. [PMID: 23401750 PMCID: PMC3564433 DOI: 10.1155/2013/136028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 12/23/2012] [Indexed: 02/07/2023] Open
Abstract
Mitochondrial dysfunction is implicated in many cardiovascular diseases, including hypertension, and may be associated with an overactive renin-angiotensin system (RAS). Angiotensin (Ang) II, a potent vasoconstrictor hormone of the RAS, also impairs baroreflex and mitochondrial function. Most deleterious cardiovascular actions of Ang II are thought to be mediated by NADPH-oxidase- (NOX-) derived reactive oxygen species (ROS) that may also stimulate mitochondrial oxidant release and alter redox-sensitive signaling pathways in the brain. Within the RAS, the actions of Ang II are counterbalanced by Ang-(1–7), a vasodilatory peptide known to mitigate against increased oxidant stress. A balance between Ang II and Ang-(1–7) within the brain dorsal medulla contributes to maintenance of normal blood pressure and proper functioning of the arterial baroreceptor reflex for control of heart rate. We propose that Ang-(1–7) may negatively regulate the redox signaling pathways activated by Ang II to maintain normal blood pressure, baroreflex, and mitochondrial function through attenuating ROS (NOX-generated and/or mitochondrial).
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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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Arnold AC, Sakima A, Kasper SO, Vinsant S, Garcia-Espinosa MA, Diz DI. The brain renin-angiotensin system and cardiovascular responses to stress: insights from transgenic rats with low brain angiotensinogen. J Appl Physiol (1985) 2012; 113:1929-36. [PMID: 22984245 DOI: 10.1152/japplphysiol.00569.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The renin-angiotensin system (RAS) has been identified as an attractive target for the treatment of stress-induced cardiovascular disorders. The effects of angiotensin (ANG) peptides during stress responses likely result from an integration of actions by circulating peptides and brain peptides derived from neuronal and glial sources. The present review focuses on the contribution of endogenous brain ANG peptides to pathways involved in cardiovascular responses to stressors. During a variety of forms of stress, neuronal pathways in forebrain areas containing ANG II or ANG-(1-7) are activated to stimulate descending angiotensinergic pathways that increase sympathetic outflow to increase blood pressure. We provide evidence that glia-derived ANG peptides influence brain AT(1) receptors. This appears to result in modulation of the responsiveness of the neuronal pathways activated during stressors that elevate circulating ANG peptides to activate brain pathways involving descending hypothalamic projections. It is well established that increased cardiovascular reactivity to stress is a significant predictor of hypertension and other cardiovascular diseases. This review highlights the importance of understanding the impact of RAS components from the circulation, neurons, and glia on the integration of cardiovascular responses to stressors.
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Affiliation(s)
- Amy C Arnold
- The Hypertension & Vascular Research Center and the Departments of General Surgery and Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157-1032, USA
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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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Nautiyal M, Katakam PVG, Busija DW, Gallagher PE, Tallant EA, Chappell MC, Diz DI. Differences in oxidative stress status and expression of MKP-1 in dorsal medulla of transgenic rats with altered brain renin-angiotensin system. Am J Physiol Regul Integr Comp Physiol 2012; 303:R799-806. [PMID: 22914751 DOI: 10.1152/ajpregu.00566.2011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
ANG II-stimulated production of reactive oxygen species (ROS) through NADPH oxidase is suggested to activate MAPK pathways, which are implicated in neurally mediated pressor effects of ANG II. Emerging evidence suggests that ANG-(1-7) up regulates MAPK phosphatases to reduce MAPK signaling and attenuate actions of ANG II. Whether angiotensin peptides participate in long-term regulation of these systems in the brain is not known. Therefore, we determined tissue and mitochondrial ROS, as well as expression and activity of MAPK phosphatase-1 (MKP-1) in brain dorsal medullary tissue of hypertensive transgenic (mRen2)27 rats exhibiting higher ANG II/ANG-(1-7) tone or hypotensive transgenic rats with targeted decreased glial expression of angiotensinogen, ASrAOGEN (AS) exhibiting lower ANG II/ANG-(1-7) tone compared with normotensive Sprague-Dawley (SD) rats that serve as the control strain. Transgenic (mRen2)27 rats showed higher medullary tissue NADPH oxidase activity and dihydroethidium fluorescence in isolated mitochondria vs. SD or AS rats. Mitochondrial uncoupling protein 2 was lower in AS and unchanged in (mRen2)27 compared with SD rats. MKP-1 mRNA and protein expression were higher in AS and unchanged in (mRen2)27 compared with SD rats. AS rats also had lower phosphorylated ERK1/2 and JNK consistent with higher MKP-1 activity. Thus, an altered brain renin-angiotensin system influences oxidative stress status and regulates MKP-1 expression. However, there is a dissociation between these effects and the hemodynamic profiles. Higher ROS was associated with hypertension in (mRen2)27 and normal MKP-1, whereas the higher MKP-1 was associated with hypotension in AS, where ROS was normal relative to SD rats.
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Affiliation(s)
- Manisha Nautiyal
- The Hypertension and Vascular Research Center, Wake Forest Univ. School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1032, USA
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The functional role of PI3K in maintenance of blood pressure and baroreflex suppression in (mRen2)27 and mRen2.Lewis rat. J Cardiovasc Pharmacol 2012; 58:367-73. [PMID: 21697727 DOI: 10.1097/fjc.0b013e31822555ca] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The phosphatidylinositol 3-kinase (PI3K)-dependent signaling pathway in brain of spontaneously hypertensive rats, but not Wistar-Kyoto (WKY) rats, contributes to elevated mean arterial pressure (MAP). The role of PI3K in the regulation of blood pressure or autonomic function in the nucleus tractus solitarii (NTS) is yet to be established in other Ang II-dependent models of hypertension. Thus, we microinjected PI3K inhibitors, wortmannin or LY294002, into the NTS, and measured MAP, baroreflex sensitivity (BRS) for heart rate (HR) control, and HR variability (HRV) in mRen2.Lewis congenic and (mRen2)27 transgenic rats. Bilateral NTS microinjections of wortmannin (100 nmol/L; 50 nL) reduced MAP in (mRen2)27 and mRen2.Lewis rats (33 ± 5 mm Hg, n = 7, and 32 ± 6 mm Hg, n = 9, respectively) for approximately 90 minutes. Spectral and sequence analysis showed improvements in spontaneous BRS and HRV (50%-100%) after treatment in both hypertensive strains. Injections of wortmannin into NTS of Hannover Sprague-Dawley or Lewis control rats failed to alter MAP, BRS, or HRV. In mRen2.Lewis, but not in control Lewis rats, LY294002 (50 μmole/L) reduced MAP and increased BRS and HRV similar to wortmannin. Thus, the pharmacologic blockade of the PI3K signaling pathway in NTS reveals an important contribution to resting MAP and BRS in rats with overexpression of the Ren2 gene.
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Isa K, Arnold AC, Westwood BM, Chappell MC, Diz DI. Angiotensin-converting enzyme inhibition, but not AT(1) receptor blockade, in the solitary tract nucleus improves baroreflex sensitivity in anesthetized transgenic hypertensive (mRen2)27 rats. Hypertens Res 2011; 34:1257-62. [PMID: 21937997 PMCID: PMC4160904 DOI: 10.1038/hr.2011.110] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Transgenic hypertensive (mRen2)27 rats overexpress the murine Ren2 gene and have impaired baroreflex sensitivity (BRS) for control of the heart rate. Removal of endogenous angiotensin (Ang)-(1-7) tone using a receptor blocker does not further lower BRS. Therefore, we assessed whether blockade of Ang II with a receptor antagonist or combined reduction in Ang II and restoration of endogenous Ang-(1-7) levels with Ang-converting enzyme (ACE) inhibition will improve BRS in these animals. Bilateral solitary tract nucleus (nTS) microinjections of the AT(1) receptor blocker, candesartan (CAN, 24 pmol in 120 nl, n=9), or a peptidic ACE inhibitor, bradykinin (BK) potentiating nonapeptide (Pyr-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro; BPP9α, 9 nmol in 60 nl, n=12), in anesthetized male (mRen2)27 rats (15-25 weeks of age) show that AT(1) receptor blockade had no significant effect on BRS, whereas microinjection of BPP9α improved BRS over 60-120 min. To determine whether Ang-(1-7) or BK contribute to the increase in BRS, separate experiments using the Ang-(1-7) receptor antagonist D-Ala(7)-Ang-(1-7) or the BK antagonist HOE-140 showed that only the Ang-(1-7) receptor blocker completely reversed the BRS improvement. Thus, acute AT(1) blockade is unable to reverse the effects of long-term Ang II overexpression on BRS, whereas ACE inhibition restores BRS over this same time frame. As the BPP9α potentiation of BK actions is a rapid phenomenon, the likely mechanism for the observed delayed increase in BRS is through ACE inhibition and elevation of endogenous Ang-(1-7).
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Affiliation(s)
- Katsunori Isa
- Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1032, USA
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20
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Kar S, Gao L, Belatti DA, Curry PL, Zucker IH. Central angiotensin (1-7) enhances baroreflex gain in conscious rabbits with heart failure. Hypertension 2011; 58:627-34. [PMID: 21844487 DOI: 10.1161/hypertensionaha.111.177600] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In chronic heart failure (CHF), arterial baroreflex function is impaired, in part, by activation of the central renin-angiotensin system. A metabolite of angiotensin (Ang) II, Ang-(1-7), has been shown to exhibit cardiovascular effects that are in opposition to that of Ang II. However, the action of Ang-(1-7) on sympathetic outflow and baroreflex function is not well understood, especially in CHF. The aim of this study was to determine the effect of intracerebroventricular infusion of Ang-(1-7) on baroreflex control of heart rate and renal sympathetic nerve activity in conscious rabbits with CHF. We hypothesized that central Ang-(1-7) would improve baroreflex function in CHF. Ang-(1-7) (2 nmol/1 μL per hour) or artificial cerebrospinal fluid (1 μL per hour) was infused by an osmotic minipump for 4 days in sham and pacing-induced CHF rabbits (n=3 to 6 per group). Ang-(1-7) treatment had no effects in sham rabbits but reduced heart rate and increased baroreflex gain (7.4±1.5 versus 2.5±0.4 bpm/mm Hg; P<0.05) in CHF rabbits. The Ang-(1-7) antagonist A779 (8 nmol/1 μL per hour) blocked the improvement in baroreflex gain in CHF. Baroreflex gain increased in CHF+Ang-(1-7) animals when only the vagus was allowed to modulate baroreflex control by acute treatment with the β-1 antagonist metoprolol, indicating increased vagal tone. Baseline renal sympathetic nerve activity was significantly lower, and baroreflex control of renal sympathetic nerve activity was enhanced in CHF rabbits receiving Ang-(1-7). These data suggest that augmentation of central Ang-(1-7) inhibits sympathetic outflow and increases vagal outflow in CHF, thus contributing to enhanced baroreflex gain in this disease state.
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Affiliation(s)
- Sumit Kar
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA
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21
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Diz DI, Arnold AC, Nautiyal M, Isa K, Shaltout HA, Tallant EA. Angiotensin peptides and central autonomic regulation. Curr Opin Pharmacol 2011; 11:131-7. [PMID: 21367658 DOI: 10.1016/j.coph.2011.02.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 02/08/2011] [Indexed: 10/18/2022]
Abstract
Aging, hypertension, and fetal-programmed cardiovascular disease are associated with a functional deficiency of angiotensin (Ang)-(1-7) in the brain dorsomedial medulla. The resulting unrestrained activity of Ang II in brainstem regions negatively impacts resting mean arterial pressure, sympathovagal balance, and baroreflex sensitivity for control of heart rate. The differential effects of Ang II and Ang-(1-7) may be related to the cellular sources of these peptides as well as different precursor pathways. Long-term alterations of the brain renin-angiotensin system may influence signaling pathways including phosphoinositol-3-kinase and mitogen-activated protein kinase and their downstream mediators, and as a consequence may influence metabolic function. Differential regulation of signaling pathways in aging and hypertension by Ang II versus Ang-(1-7) may contribute to the autonomic dysfunction accompanying these states.
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Affiliation(s)
- Debra I Diz
- The Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
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22
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de Moura MM, dos Santos RAS, Campagnole-Santos MJ, Todiras M, Bader M, Alenina N, Haibara AS. Altered cardiovascular reflexes responses in conscious Angiotensin-(1-7) receptor Mas-knockout mice. Peptides 2010; 31:1934-9. [PMID: 20603170 DOI: 10.1016/j.peptides.2010.06.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 06/23/2010] [Accepted: 06/24/2010] [Indexed: 11/21/2022]
Abstract
This study evaluated the physiological importance of Angiotensin-(1-7) receptor Mas on reflex control of circulation. Experiments were performed in male Mas-knockout (Mas-KO) and Wild Type (WT) conscious mice (12-20 wk of age). Baroreceptor reflex was evaluated by the bradycardic response induced by phenylephrine (0.25 μg/5 μl, i.v.). Bezold-Jarisch reflex was evaluated by phenylbiguanide (0.5 μg/5 μl, i.v.) and chemoreflex by potassium cyanide (2.5 μg/5 μl, i.v.). Baseline mean arterial pressure was higher in Mas-KO (n=14) as compared with WT mice (n=18) (118±1 mmHg vs. 109±2 mmHg); however, heart rate was similar in both strains (615±30 bpm vs. 648±13 bpm). Baroreflex bradycardia was lower (0.78±0.44 ms/mmHg vs. 1.30±0.14 ms/mmHg) in Mas-KO compared with WT mice. The depressor (-17±5 mmHg vs. -45±6 mmHg) and bradycardic (-212±36 bpm vs. -391±29 bpm) components of the Bezold-Jarisch reflex were also lower in Mas-KO mice. In addition, chemoreflex pressor response (+20±3 mmHg vs. +12±0.8 mmHg) and bradycardic response (-250±74 bpm vs. -52±26 bpm) were significantly higher in Mas-KO. These results further advances previous studies by showing that the lack of Mas receptor induced important imbalance in the neural control of blood pressure, altering not only the baroreflex but also the chemo- and Bezold-Jarisch reflexes.
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Garcia-Espinosa MA, Shaltout HA, Olson J, Westwood BM, Robbins ME, Link K, Diz DI. Proton magnetic resonance spectroscopy detection of neurotransmitters in dorsomedial medulla correlate with spontaneous baroreceptor reflex function. Hypertension 2010; 55:487-93. [PMID: 20065146 DOI: 10.1161/hypertensionaha.109.145722] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Control of heart rate variability via modulation of sympathovagal balance is a key function of nucleus tractus solitarii and the dorsal motor nucleus of the vagus localized in the dorsomedial medulla oblongata. Normal blood pressure regulation involves precise balance of glutamate (Glu)-glutamine-gamma-aminobutyric acid transmitter systems, and angiotensin II modulates these transmitters to produce tonic suppression of reflex function. It is not known, however, whether other brain transmitters/metabolites are indicators of baroreflex function. This study establishes the concept that comprehensive baseline transmitter/metabolite profiles obtained using in vivo (1)H magnetic resonance spectroscopy in rats with well-characterized differences in resting blood pressure and baroreflex function can be used as indices of autonomic balance or baroreflex sensitivity. Transgenic rats with over-expression of renin [m(Ren2)27] or under-expression of glial-angiotensinogen (ASrAogen) were compared with Sprague-Dawley rats. Glu concentration in the dorsal medulla is significantly higher in ASrAogen rats compared with either Sprague-Dawley or (mRen2)27 rats. Glu levels and the ratio of Glu:glutamine correlated positively with indices of higher vagal tone consistent with the importance of these neurotransmitters in baroreflex function. Interestingly, the levels of choline-containing metabolites showed a significant positive correlation with spontaneous baroreflex sensitivity and a negative correlation with sympathetic tone. Thus, we demonstrate the concept that noninvasive assessment of neurochemical biomarkers may be used as an index of baroreflex sensitivity.
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Affiliation(s)
- Maria A Garcia-Espinosa
- Department of Radiation Oncology, Wake Forest University School of Medicine, Hypertension and Vascular Research Center, Winston-Salem, NC 27157-1032, 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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Grobe JL, Xu D, Sigmund CD. An intracellular renin-angiotensin system in neurons: fact, hypothesis, or fantasy. Physiology (Bethesda) 2008; 23:187-93. [PMID: 18697992 DOI: 10.1152/physiol.00002.2008] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The renin-angiotensin system in the brain acts to regulate a number of physiological processes. Evidence suggests that angiotensin peptides may act as neurotransmitters, although their biosynthetic pathways are poorly understood. We review evidence for neuronal production of angiotensin peptides and hypothesize that angiotensin may be synthesized intracellularly in neurons.
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Affiliation(s)
- Justin L Grobe
- Department of Internal Medicine, Center on Functional Genomics of Hypertension, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
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26
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Angiotensin-(1-7) and baroreflex function in nucleus tractus solitarii of (mRen2)27 transgenic rats. J Cardiovasc Pharmacol 2008; 51:542-8. [PMID: 18475201 DOI: 10.1097/fjc.0b013e3181734a54] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND Endogenous angiotensin (Ang)-(1-7) enhances, while Ang II attenuates, baroreceptor sensitivity (BRS) for reflex control of heart rate (HR) in Sprague-Dawley (SD) rats. In (mRen2)27 renin transgenic rats [(mRen2)], there is overexpression of the mouse Ren2 gene in brain, leading to elevated Ang II and reduced Ang-(1-7) in brain medullary, and associated with hypertension and impaired BRS. METHODS We therefore tested the contribution of endogenous Ang-(1-7) to BRS for control of HR and responses to cardiac vagal chemosensitive afferent fiber activation (CVA) with phenylbiguanide (PBG) in anesthetized SD and (mRen2) 27 rats before and after bilateral nucleus of the solitary tract (nTS) injection of the Ang-(1-7) receptor antagonist (D-Ala7)-Ang-(1-7). RESULTS (mRen2) 27 rats exhibited a approximately 50% impairment in BRS as compared with SD (P < 0.05). (D-Ala7)-Ang-(1-7) attenuated BRS by approximately 50% in SD rats, but was without effect in (mRen2) 27 rats. (D-Ala7)-Ang-(1-7) did not alter the responses to CVA by PBG (iv bolus) in either strain. There were no differences in the depressor effects of Ang-(1-7) injected into the nTS, nor were levels of mRNA different for angiotensin-converting enzyme, angiotensin-converting enzyme 2, neprilysin, or the mas receptor in medullary tissue from SD versus (mRen2)27 rats. CONCLUSION Endogenous Ang-(1-7) does not provide tonic input in the nTS to modulate BRS for control of HR in (mRen2)27 rats, which may contribute to impairment of BRS in these animals.
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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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Caligiorne SM, Silva AQG, Fontes MAP, Silva JR, Baltatu O, Bader M, Santos RAS, Campagnole-Santos MJ. Baroreflex control of heart rate and renal sympathetic nerve activity in rats with low brain angiotensinogen. Neuropeptides 2008; 42:159-68. [PMID: 18242696 DOI: 10.1016/j.npep.2007.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 12/13/2007] [Accepted: 12/15/2007] [Indexed: 01/30/2023]
Abstract
The main objective of the present study was to evaluate baroreceptor control of heart rate (HR) and renal sympathetic nerve activity (RSNA) in transgenic rats (TG) with low angiotensinogen production in glial cells, TGR(ASrAogen)-680. In addition, the sympathetic and vagal autonomic tonus to the heart was investigated. As previously shown, TG rats presented a lower arterial pressure (AP) and HR. However, TG rats had decreased AP variability during the night (8.9+/-0.4 mmHg vs 9.8+/-0.3 mmHg, in SD) accompanied by an increase in HR variability (39+/-1 beats/min vs 35+/-1 beats/min, in SD) and augmented locomotor activity during the night (3.5+/-0.3 counts/min vs 2.5+/-0.2 counts/min, in SD). In addition, TG rats presented increased baroreflex sensitivity for the RSNA (slope of line that correlates decreases in RSNA and increases in AP=1.36+/-0.18 vs 0.77+/-0.1, in SD) and an increased sensitivity for both the baroreflex bradycardia (0.79+/-0.04 ms/mmHg vs 0.52+/-0.04 ms/mmHg, in SD) and tachycardia (1.46+/-0.1 ms/mmHg vs 0.93+/-0.01 ms/mmHg, in SD). Further, TG rats had increased vagal tonus (25+/-3 beats/min vs 11+/-4 beats/min in SD) without significant change in the sympathetic tonus to the heart. These results confirm and extend previous observations showing that glial angiotensinogen, the main source of brain RAS peptides, importantly modulates sympathetic tonus, at least to the renal nerve, and vagal tonus to the heart.
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Affiliation(s)
- Sordaini M Caligiorne
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av Antonio Carlos, 6627-ICB, 31270-901 Belo Horizonte, MG, Brazil
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Diz DI, Garcia-Espinosa MA, Gegick S, Tommasi EN, Ferrario CM, Ann Tallant E, Chappell MC, Gallagher PE. Injections of angiotensin-converting enzyme 2 inhibitor MLN4760 into nucleus tractus solitarii reduce baroreceptor reflex sensitivity for heart rate control in rats. Exp Physiol 2008; 93:694-700. [PMID: 18356558 DOI: 10.1113/expphysiol.2007.040261] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Injections of the angiotensin(1-7) [Ang(1-7)] antagonist [d-Ala7]-Ang(1-7) into the nucleus of the solitary tract (NTS) of Sprague-Dawley rats reduce baroreceptor reflex sensitivity (BRS) for control of heart rate by approximately 40%, whereas injections of the angiotensin II (Ang II) type 1 receptor antagonist candesartan increase BRS by 40% when reflex bradycardia is assessed. The enzyme angiotensin-converting enzyme 2 (ACE2) is known to convert Ang II to Ang(1-7). We report that ACE2 activity, as well as ACE and neprilysin activities, are present in plasma membrane fractions of the dorsomedial medulla of Sprague-Dawley rats. Moreover, we show that BRS for reflex bradycardia is attenuated (1.16 +/- 0.29 ms mmHg-1 before versus 0.33 +/- 0.11 ms mmHg-1 after; P < 0.05; n = 8) 30-60 min following injection of the selective ACE2 inhibitor MLN4760 (12 pmol in 120 nl) into the NTS. These findings support the concept that within the NTS, local synthesis of Ang(1-7) from Ang II is required for normal sensitivity for the baroreflex control of heart rate in response to increases in arterial pressure.
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Affiliation(s)
- Debra I Diz
- The Hypertension & Vascular Research Center, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1032, USA.
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Arnold AC, Sakima A, Ganten D, Ferrario CM, Diz DI. Modulation of reflex function by endogenous angiotensins in older transgenic rats with low glial angiotensinogen. Hypertension 2008; 51:1326-31. [PMID: 18347230 DOI: 10.1161/hypertensionaha.107.106005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Age-related impairments in baroreflex sensitivity in Sprague-Dawley rats are associated with low solitary tract nucleus content of angiotensin-(1-7). However, transgenic rats with low-brain angiotensinogen resulting from glial overexpression of an antisense oligonucleotide to angiotensinogen (ASrAOGEN) are spared age-related declines in cardiovascular function characteristic of Sprague-Dawley rats. We examine whether cardiovascular and reflex actions of angiotensin-(1-7) persist in the solitary tract nucleus of older (16 to 22 months) ASrAOGEN rats. Baroreflex sensitivity for control of heart rate and chemosensitive vagal afferent activation in response to phenylbiguanide were measured before and after bilateral microinjection of the angiotensin II type 1 receptor antagonist candesartan and angiotensin-(1-7) receptor antagonist (D-Ala(7))-angiotensin-(1-7) in urethane/chloralose-anesthetized rats. In older anesthetized ASrAOGEN rats, candesartan had no effect, whereas (D-Ala(7))-angiotensin-(1-7) significantly reduced baroreflex sensitivity (1.80+/-0.43 versus 0.50+/-0.17 ms/mm Hg). Phenylbiguanide responses were attenuated by injection of candesartan (-79+/-6 versus -55+/-12 mm Hg and -277+/-12 versus -156+/-27 bpm; P<0.05). In addition, resting blood pressure was reduced by injection of candesartan or (D-Ala(7))-angiotensin-(1-7). Within the solitary tract nucleus of older ASrAOGEN rats, it appears that glial angiotensinogen is the main source of angiotensin II attenuation of baroreflex sensitivity; endogenous angiotensin-(1-7) from nonglial sources enhances baroreflex sensitivity; nonglial sources of angiotensin II contribute to chemosensitive vagal afferent activation; and receptors for both peptides modulate resting arterial pressure under anesthesia. These results suggest a novel mechanism for the preservation of baroreflex sensitivity during aging.
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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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