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Sutovska H, Molcan L, Majzunova M, Sykora M, Kopkan L, Zeman M. Mineralocorticoid receptor blockade protects the kidneys but does not affect inverted blood pressure rhythm in hypertensive transgenic (mRen-2)27 rats. Mol Cell Endocrinol 2023; 572:111967. [PMID: 37210027 DOI: 10.1016/j.mce.2023.111967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/17/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023]
Abstract
Aldosterone regulates blood pressure (BP) through water and sodium balance. In our study, we studied if continuous treatment with a mineralocorticoid receptor antagonist, spironolactone (30 mg/kg/day) for 20 days can: 1) attenuate hypertension development and restore inverted 24-h BP rhythm in hypertensive transgenic (mRen-2)27 rats (TGR) measured by telemetry; 2) improve function of the kidneys and heart; 3) be protective against high salt load (1% in water) by mitigating oxidative injury and improving kidney function. Spironolactone decreased albuminuria and 8-isoprostane in normal and salt load conditions in BP-independent effects. Salt load increased BP, impaired autonomic balance, suppressed plasma aldosterone level and increased natriuresis, albuminuria and oxidative injury in TGR. Spironolactone did not restore the inverted 24-h rhythm of BP in TGR, therefore, mineralocorticoids are not crucial in regulation of BP daily profile. Spironolactone improved kidney function, decreased oxidative stress and was protective against high salt load in the BP-independent manner.
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Affiliation(s)
- Hana Sutovska
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Lubos Molcan
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Miroslava Majzunova
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Matus Sykora
- Centre of Experimental Medicine, Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovak Republic.
| | - Libor Kopkan
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic.
| | - Michal Zeman
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
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Prasad M, Rajarajeswari D, Ramlingam K, Viswakumar R, Suneel B, Conjeevaram J, Aruna P, Fathima N, Vishwakarma SK, Khan AA. Association of Angiotensin II Type 1 Receptor (AT1R) Gene Polymorphism with Angiotensin II Serum Levels in Patients with Essential Hypertension. Indian J Clin Biochem 2023; 38:110-119. [PMID: 36684488 PMCID: PMC9852369 DOI: 10.1007/s12291-022-01041-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/30/2022] [Indexed: 01/25/2023]
Abstract
Essential hypertension (EH) is a multifactorial, polygenic condition, and is one of the most important comorbidities that contributes to stroke, myocardial infarction, cardiac failure, and renal failure. The continuous increasing rate of morbidity and mortality associated with EH presents an unmet need of population-based studies to explore pathophysiology as well as newer strategies for better diagnosis, prognosis and treatment. This study aimed to determine genotype and allele frequencies of A1166C polymorphism of AT1R gene in Indian patients with EH and correlated with serum levels of Angiotensin II. A total of 200 patients with EH and 200 age- and gender-matched control individuals were included in this study from the General Medicine Department Outpatient at Narayana Medical College and Hospital, Nellore, Andhra Pradesh, India. Patients with systolic blood pressure (SBP) ≥ 140 mmHg and/or diastolic blood pressure (DBP) ≥ 90 mmHg were considered as hypertensive. The findings of this study revealed significantly increased risk of C/A heterozygote and allele C in both men and women. Moreover, both men and women patients with EH showed higher serum levels of Angiotensin II with C/A as well as AA genotypes. These findings indicate a significant association of 1166 C/A polymorphism of the AT1R gene with increased risk of hypertension in Indian population.
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Affiliation(s)
- M. Prasad
- Department of Biochemistry, Narayana Medical College and Hospital, Chinthareddy Palem, Nellore, Andhra Pradesh 524003 India
| | - D. Rajarajeswari
- Department of Biochemistry, Narayana Medical College and Hospital, Chinthareddy Palem, Nellore, Andhra Pradesh 524003 India
| | - K. Ramlingam
- Department of Biochemistry, Narayana Medical College and Hospital, Chinthareddy Palem, Nellore, Andhra Pradesh 524003 India
| | - R. Viswakumar
- Department of Biochemistry, Narayana Medical College and Hospital, Chinthareddy Palem, Nellore, Andhra Pradesh 524003 India
| | - B. Suneel
- Department of Biochemistry, Narayana Medical College and Hospital, Chinthareddy Palem, Nellore, Andhra Pradesh 524003 India
| | - Jyothi Conjeevaram
- Department of Community Medicine, Narayana Medical College, Nellore, Andhra Pradesh 524003 India
| | - P. Aruna
- Department of Biochemistry, ACSR Government Medical College, Dargamitta, Nellore, Andhra Pradesh 524002 India
| | - Nusrath Fathima
- Central Laboratory for Stem Cell Research & Translational Medicine, Centre for Liver Research and Diagnostics, Deccan College of Medical Sciences, Kanchanbagh, Hyderabad, Telangana 500058 India
| | - Sandeep Kumar Vishwakarma
- Central Laboratory for Stem Cell Research & Translational Medicine, Centre for Liver Research and Diagnostics, Deccan College of Medical Sciences, Kanchanbagh, Hyderabad, Telangana 500058 India
| | - Aleem Ahmed Khan
- Central Laboratory for Stem Cell Research & Translational Medicine, Centre for Liver Research and Diagnostics, Deccan College of Medical Sciences, Kanchanbagh, Hyderabad, Telangana 500058 India
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Repova K, Baka T, Krajcirovicova K, Stanko P, Aziriova S, Reiter RJ, Simko F. Melatonin as a Potential Approach to Anxiety Treatment. Int J Mol Sci 2022; 23:ijms232416187. [PMID: 36555831 PMCID: PMC9788115 DOI: 10.3390/ijms232416187] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/02/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Anxiety disorders are the most common mental diseases. Anxiety and the associated physical symptoms may disturb social and occupational life and increase the risk of somatic diseases. The pathophysiology of anxiety development is complex and involves alterations in stress hormone production, neurosignaling pathways or free radical production. The various manifestations of anxiety, its complex pathophysiological background and the side effects of available treatments underlie the quest for constantly seeking therapies for these conditions. Melatonin, an indolamine produced in the pineal gland and released into the blood on a nightly basis, has been demonstrated to exert anxiolytic action in animal experiments and different clinical conditions. This hormone influences a number of physiological actions either via specific melatonin receptors or by receptor-independent pleiotropic effects. The underlying pathomechanism of melatonin's benefit in anxiety may reside in its sympatholytic action, interaction with the renin-angiotensin and glucocorticoid systems, modulation of interneuronal signaling and its extraordinary antioxidant and radical scavenging nature. Of importance, the concentration of this indolamine is significantly higher in cerebrospinal fluid than in the blood. Thus, ensuring sufficient melatonin production by reducing light pollution, which suppresses melatonin levels, may represent an endogenous neuroprotective and anxiolytic treatment. Since melatonin is freely available, economically undemanding and has limited side effects, it may be considered an additional or alternative treatment for various conditions associated with anxiety.
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Affiliation(s)
- Kristina Repova
- Institute of Pathophysiology, Faculty of Medicine, Comenius University, Sasinkova 4, 81108 Bratislava, Slovakia
| | - Tomas Baka
- Institute of Pathophysiology, Faculty of Medicine, Comenius University, Sasinkova 4, 81108 Bratislava, Slovakia
| | - Kristina Krajcirovicova
- Institute of Pathophysiology, Faculty of Medicine, Comenius University, Sasinkova 4, 81108 Bratislava, Slovakia
| | - Peter Stanko
- Institute of Pathophysiology, Faculty of Medicine, Comenius University, Sasinkova 4, 81108 Bratislava, Slovakia
| | - Silvia Aziriova
- Institute of Pathophysiology, Faculty of Medicine, Comenius University, Sasinkova 4, 81108 Bratislava, Slovakia
| | - Russel J. Reiter
- Department of Cell Systems and Anatomy, UT Health San Antonio, Long School of Medicine, San Antonio, TX 78229, USA
| | - Fedor Simko
- Institute of Pathophysiology, Faculty of Medicine, Comenius University, Sasinkova 4, 81108 Bratislava, Slovakia
- 3rd Department of Internal Medicine, Faculty of Medicine, Comenius University, 83305 Bratislava, Slovakia
- Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, 84505 Bratislava, Slovakia
- Correspondence: ; Tel.: +421-(0)2-59357276
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Kahlon T, Carlisle S, Otero Mostacero D, Williams N, Trainor P, DeFilippis AP. Angiotensinogen: More Than its Downstream Products: Evidence From Population Studies and Novel Therapeutics. JACC. HEART FAILURE 2022; 10:699-713. [PMID: 35963818 DOI: 10.1016/j.jchf.2022.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 06/08/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
The renin-angiotensin-aldosterone system (RAAS) is a well-defined pathway playing a key role in maintaining circulatory homeostasis. Abnormal activation of RAAS contributes to development of cardiovascular disease, including heart failure, cardiac hypertrophy, hypertension, and atherosclerosis. Although several key RAAS enzymes and peptide hormones have been thoroughly investigated, the role of angiotensinogen-the precursor substrate of the RAAS pathway-remains less understood. The study of angiotensinogen single-nucleotide polymorphisms (SNPs) has provided insight into associations between angiotensinogen and hypertension, congestive heart failure, and atherosclerotic cardiovascular disease. Targeted drug therapy of RAAS has dramatically improved clinical outcomes for patients with heart failure, myocardial infarction, and hypertension. However, all such therapeutics block RAAS components downstream of angiotensinogen and elicit compensatory pathways that limit their therapeutic efficacy as monotherapy. Upstream RAAS targeting by an angiotensinogen inhibitor has the potential to be more efficacious in patients with suboptimal RAAS inhibition and has a better safety profile than multiagent RAAS blockade. Newly developed therapeutics that target angiotensinogen through antisense oligonucleotides or silencer RNA technologies are providing a novel perspective into the pathobiology of angiotensinogen and show promise as the next frontier in the treatment of cardiovascular disease.
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Affiliation(s)
- Tanvir Kahlon
- Division of Cardiovascular Medicine, University of Louisville, Louisville, Kentucky, USA
| | - Samantha Carlisle
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico, USA
| | - Diana Otero Mostacero
- Division of Cardiovascular Medicine, University of Louisville, Louisville, Kentucky, USA
| | - Nina Williams
- Warren Clinic Cardiology of Tulsa, St Francis Hospital, Tulsa, Oklahoma, USA
| | - Patrick Trainor
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico, USA
| | - Andrew P DeFilippis
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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Letter to the Editor: Brain renin-angiotensin system and liver-directed siRNA targeted to angiotensinogen. Clin Sci (Lond) 2021; 135:907-910. [PMID: 33835151 DOI: 10.1042/cs20210163] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/20/2021] [Accepted: 03/29/2021] [Indexed: 12/19/2022]
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Xu Y, Rong J, Zhang Z. The emerging role of angiotensinogen in cardiovascular diseases. J Cell Physiol 2020; 236:68-78. [PMID: 32572956 DOI: 10.1002/jcp.29889] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 06/09/2020] [Indexed: 12/11/2022]
Abstract
Angiotensinogen (AGT) is the unique precursor of all angiotensin peptides. Many of the basic understandings of AGT in cardiovascular diseases have come from research efforts to define its effects on blood pressure regulation. The development of novel techniques targeting AGT manipulation such as genetic animal models, adeno-associated viral approaches, and antisense oligonucleotides made it possible to deeply investigate the relationship between AGT and cardiovascular diseases. In this brief review, we provide contemporary insights into the emerging role of AGT in cardiovascular diseases. In light of the recent progress, we emphasize some newly recognized features and mechanisms of AGT in heart failure, hypertension, atherosclerosis, and cardiovascular risk factors.
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Affiliation(s)
- Yinchuan Xu
- Department of Cardiology, The Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Jiabing Rong
- Department of Cardiology, The Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Zhaocai Zhang
- Department of Critical Care Medicine, The Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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Liu Y, Lin Y, Zhang MM, Li XH, Liu YY, Zhao J, Shi L. The relationship of plasma renin, angiotensin, and aldosterone levels to blood pressure variability and target organ damage in children with essential hypertension. BMC Cardiovasc Disord 2020; 20:296. [PMID: 32546130 PMCID: PMC7298948 DOI: 10.1186/s12872-020-01579-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 06/10/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND To investigate the relationships of plasma renin, angiotensin, and aldosterone levels to blood pressure variability and target organ damage in children with essential hypertension. METHODS A case-control study was conducted on 132 children diagnosed with essential hypertension (103 males and 29 females with the mean age of 11.8 ± 2.4 years). The plasma RAAS levels were measured using the enhanced chemiluminescence method, the ambulatory blood pressure was monitored for 24 h, and then the average real variability (ARV) was calculated. Data on indicators were used for assessing cardiac and renal damages. The correlations of plasma renin, angiotensin, and aldosterone (RAAS) levels to blood pressure variability (BPV) and target organ damage (TOD) were studied. A comparison between the groups was conducted using SPSS 20. RESULTS Among the 132 children, 55 cases had target organ damage. The 24-h ARV and the daytime ARV of the systolic blood pressure of the high angiotensin II (AT II) group was significantly higher than that of the normal AT II group (t = 2.175, P = 0.031; t = 2.672, P = 0.009). Plasma AT II and aldosterone levels were significantly associated with the left ventricular mass index (r = 0.329, P = 0.0001; r = 0.175, P = 0.045). Linear regression analysis showed that AT II [β ± s.e. = 0.025 ± 0.006, 95% CI (0.013-0.038), P = 0.0001] and aldosterone [β ± s.e. = 0.021 ± 0.007, 95% CI (0.008-0.034), P = 0.002] were risk factors for LVH. CONCLUSIONS The AT II level in children with essential hypertension affected the variability of the 24-h and the daytime SBP. Plasma AT II and aldosterone levels were associated with cardiac damage. Results from this study indicated that AT II and aldosterone are risk factors for LVH in childhood hypertension and are of great significance for improving the clinical prognosis of pediatric patients with hypertension.
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Affiliation(s)
- Yang Liu
- Capital Institute of Pediatrics-Peking University Teaching Hospital, Beijing, 100191, China
| | - Yao Lin
- Department of Cardiology, Children's Hospital Affiliated to Capital Institute of Pediatrics, Beijing, 100020, China
| | - Ming-Ming Zhang
- Department of Cardiology, Children's Hospital Affiliated to Capital Institute of Pediatrics, Beijing, 100020, China
| | - Xiao-Hui Li
- Department of Cardiology, Children's Hospital Affiliated to Capital Institute of Pediatrics, Beijing, 100020, China
| | - Yan-Yan Liu
- Department of Cardiology, Children's Hospital Affiliated to Capital Institute of Pediatrics, Beijing, 100020, China
| | - Jing Zhao
- Capital Institute of Pediatrics-Peking University Teaching Hospital, Beijing, 100191, China.
| | - Lin Shi
- Capital Institute of Pediatrics-Peking University Teaching Hospital, Beijing, 100191, China.
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Development of obesity can be prevented in rats by chronic icv infusions of AngII but less by Ang(1-7). Pflugers Arch 2018; 470:867-881. [PMID: 29430615 DOI: 10.1007/s00424-018-2117-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 01/30/2018] [Accepted: 02/01/2018] [Indexed: 02/07/2023]
Abstract
Considering that obesity is one of the leading risks for death worldwide, it should be noted that a brain-related mechanism is involved in AngII-induced and AT1-receptor-dependent weight loss. It is moreover established that activation of the Ang(1-7)/ACE2/Mas axis reduces weight, but it remains unclear whether this Ang(1-7) effect is also mediated via a brain-related mechanism. Additionally to Sprague Dawley (SD) rats, we used TGR(ASrAOGEN) selectively lacking brain angiotensinogen, the precursor to AngII, as we speculated that effects are more pronounced in a model with low brain RAS activity. Rats were fed with high-calorie cafeteria diet. We investigated weight regulation, food behavior, and energy balance in response to chronic icv.-infusions of AngII (200 ng•h-1), or Ang(1-7) (200/600 ng•h-1) or artificial cerebrospinal fluid. High- but not low-dose Ang(1-7) slightly decreased weight gain and energy intake in SD rats. AngII showed an anti-obese efficacy in SD rats by decreasing energy intake and increasing energy expenditure and also improved glucose control. TGR(ASrAOGEN) were protected from developing obesity. However, Ang(1-7) did not reveal any effects in TGR(ASrAOGEN) and those of AngII were minor compared to SD rats. Our results emphasize that brain AngII is a key contributor for regulating energy homeostasis and weight in obesity by serving as a negative brain-related feedback signal to alleviate weight gain. Brain-related anti-obese potency of Ang(1-7) is lower than AngII but must be further investigated by using other transgenic models as TGR(ASrAOGEN) proved to be less valuable for answering this question.
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Baltatu OC, Amaral FG, Campos LA, Cipolla-Neto J. Melatonin, mitochondria and hypertension. Cell Mol Life Sci 2017; 74:3955-3964. [PMID: 28791422 PMCID: PMC11107636 DOI: 10.1007/s00018-017-2613-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 08/03/2017] [Indexed: 12/29/2022]
Abstract
Melatonin, due to its multiple means and mechanisms of action, plays a fundamental role in the regulation of the organismal physiology by fine tunning several functions. The cardiovascular system is an important site of action as melatonin regulates blood pressure both by central and peripheral interventions, in addition to its relation with the renin-angiotensin system. Besides, the systemic management of several processes, melatonin acts on mitochondria regulation to maintain a healthy cardiovascular system. Hypertension affects target organs in different ways and cellular energy metabolism is frequently involved due to mitochondrial alterations that include a rise in reactive oxygen species production and an ATP synthesis decrease. The discussion that follows shows the role played by melatonin in the regulation of mitochondrial physiology in several levels of the cardiovascular system, including brain, heart, kidney, blood vessels and, particularly, regulating the renin-angiotensin system. This discussion shows the putative importance of using melatonin as a therapeutic tool involving its antioxidant potential and its action on mitochondrial physiology in the cardiovascular system.
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Affiliation(s)
- Ovidiu C Baltatu
- Center of Innovation, Technology and Education (CITE) at Anhembi Morumbi University-Laureate International Universities, 500 Dr. Altino Bondensan Ave, São José dos Campos, SP, 12247-016, Brazil
| | - Fernanda G Amaral
- Department of Physiology, Federal University of São Paulo, 862 Botucatu St, 5th Floor, São Paulo, SP, 04023-901, Brazil
| | - Luciana A Campos
- Center of Innovation, Technology and Education (CITE) at Anhembi Morumbi University-Laureate International Universities, 500 Dr. Altino Bondensan Ave, São José dos Campos, SP, 12247-016, Brazil
| | - Jose Cipolla-Neto
- Department of Physiology, Institute of Biomedical Sciences, University of São Paulo, Av. Lineu Prestes, 1524, room 115/118, São Paulo, SP, 05508-000, Brazil.
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Huber G, Schuster F, Raasch W. Brain renin-angiotensin system in the pathophysiology of cardiovascular diseases. Pharmacol Res 2017; 125:72-90. [PMID: 28687340 DOI: 10.1016/j.phrs.2017.06.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 06/28/2017] [Accepted: 06/28/2017] [Indexed: 02/07/2023]
Abstract
Cardiovascular diseases (CVD) are among the main causes of death globally and in this context hypertension represents one of the key risk factors for developing a CVD. It is well established that the peripheral renin-angiotensin system (RAS) plays an important role in regulating blood pressure (BP). All components of the classic RAS can also be found in the brain but, in contrast to the peripheral RAS, how the endogenous RAS is involved in modulating cardiovascular effects in the brain is not fully understood yet. It is a complex system that may work differently in diverse areas of the brain and is linked to the peripheral system by the circumventricular organs (CVO), which do not have a blood brain barrier (BBB). In this review, we focus on the brain angiotensin peptides, their interactions with each other, and the consequences in the central nervous system (CNS) concerning cardiovascular control. Additionally, we present potential drug targets in the brain RAS for the treatment of hypertension.
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Affiliation(s)
- Gianna Huber
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Germany; CBBM (Center of Brain, Behavior and Metabolism), Lübeck, Germany
| | - Franziska Schuster
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Germany; CBBM (Center of Brain, Behavior and Metabolism), Lübeck, Germany
| | - Walter Raasch
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Germany; CBBM (Center of Brain, Behavior and Metabolism), Lübeck, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany.
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Boussetta N, Abedelmalek S, Aloui K, Souissi N. The effect of air pollution on diurnal variation of performance in anaerobic tests, cardiovascular and hematological parameters, and blood gases on soccer players following the Yo-Yo Intermittent Recovery Test Level-1. Chronobiol Int 2017; 34:903-920. [PMID: 28613960 DOI: 10.1080/07420528.2017.1325896] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This study aimed to investigate the effect of air pollution on diurnal variation of performance in anaerobic tests, cardiovascular and hematological parameters, and blood gases on soccer players following the Yo-Yo Intermittent Recovery Test Level-1 (YYIRT1). In a randomized order, 11 healthy soccer players (mean age: 21.8 [range: 20-24] years; height: 178.00 [range: 1.64-1.83] cm; body mass index [BMI]: 23.57 [range: 20.45-28.03] kg.m-2) performed a YYIRT1 at two different times of day (TOD) (08:00 h and 18:00 h) in two areas (i.e. polluted (PA) and non-polluted (NPA)) with a recovery period of ≥ 72 h in between, to determine the maximal oxygen uptake (VO2max). In each test session: resting oral temperature is measured, anaerobic performances (pre- and post-YYIRT1) were performed, cardiovascular parameters and blood samples were collected at: rest, 3 min and 60 min after the YYIRT1, to assess blood gases and hematological parameters. Our results showed that, agility performance, VO2max, red blood cells (RBC), hemoglobin (Hb), pH, and bicarbonate levels (HCO3-) decrease significantly (p < 0.001) following the YYIRT1 in PA compared to NPA. Likewise, the heart rate (HR), systolic blood pressure (SBP), platelets (PLT), white blood cells (WBC), neutrophiles (NEUT), lymphocytes (LYM), and partial pressure of CO2 levels (PvCO2) were significantly higher (p < 0.001) in PA. This effect was slightly accentuated at 18:00 h for some parameters (i.e. Agility, HCO3-, HR, PvCO2, RBC, SBP). However, performances of sprint and Sargent jump test (SJT), oral temperature, rate of perceived exertion scales (RPE), partial pressure of O2 (PvO2), diastolic blood pressure (DBP), and monocytes (MON) were not affected by pollution (p > 0.05). In conclusion, pollution seems to be critical for health stability and performance in response to YYIRT1 especially in the evening and the winter season. Therefore, coaches and athletes should draw attention to the potential importance of land use planning in their training sessions and competitions in the morning in polluted area to minimize the risk of pollution exposure.
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Affiliation(s)
- Nesrin Boussetta
- a Research Unit of Physical Activity, Sport and Health , National Sport Observatory of Tunisia , Tunis , Tunisia.,b High Institute of Sport and Physical Education , University of Mannouba , Ksar saïd , Tunisia
| | - Salma Abedelmalek
- c Research Laboratory ''Sports performance optimization'' National Center of Medicine and Science in Sports (CNMSS) , Tunis , Tunisia
| | - Khouloud Aloui
- d Faculty of Sciences of Bizerte, Department of Physiology , University of Carthage , Bizerte , Tunisia
| | - Nizar Souissi
- c Research Laboratory ''Sports performance optimization'' National Center of Medicine and Science in Sports (CNMSS) , Tunis , Tunisia.,e Department of Physiology and functional explorations , Sousse Faculty of Medicine , Sousse , Tunisia
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12
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Gao J, Kerut EK, Smart F, Katsurada A, Seth D, Navar LG, Kapusta DR. Sympathoinhibitory Effect of Radiofrequency Renal Denervation in Spontaneously Hypertensive Rats With Established Hypertension. Am J Hypertens 2016; 29:1394-1401. [PMID: 27538721 DOI: 10.1093/ajh/hpw089] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 07/22/2016] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Radiofrequency ablation of the renal arteries (RF-ABL) has been shown to decrease blood pressure (BP) in drug-resistant hypertensive patients who receive antihypertensive drug therapy. However, there remain questions regarding how RF-ABL influences BP independent of drug therapy and whether complete renal denervation is necessary to maximally lower BP. To study these questions, we examined the cardiovascular, sympathetic, and renal effects produced by RF-ABL of the proximal renal arteries in spontaneously hypertensive rats (SHR) with established hypertension. METHODS SHR were instrumented (telemetry) for measurement of systolic/diastolic BP (SBP/DBP). Rats then underwent Sham-ABL or RF-ABL adjacent to the renal ostium and BP was recorded for 8 weeks. Changes in sympathetic activity, 24-hour water/sodium excretion, and levels of urinary angiotensinogen (AGT), plasma renin activity, and kidney renin content (KRC) were measured in SHR. RESULTS Compared with Sham-ABL, RF-ABL produced a sustained decrease in BP. At 8 weeks, SBP/DBP was 171±6/115±3 and 183±4/129±3mm Hg for RF-ABL and Sham-ABL SHR, respectively. Correlating with the reduction in BP, RF-ABL significantly decreased the low frequency/total and low frequency/high frequency of BP variability and attenuated the hypotensive response to chlorisondamine. Kidney norepinephrine levels were markedly decreased at 8 weeks in RF-ABL vs. Sham-ABL SHR. There were no group differences in 24-hour sodium/water excretion or urinary AGT excretion rate (6 weeks) or plasma renin activity or KRC (8 weeks). In other studies, concurrent RF-ABL plus surgical denervation initially decreased BP to a greater level than RF-ABL alone, but thereafter the reduction in BP between groups was not different. CONCLUSIONS In hypertensive SHR, bilateral RF-ABL of the proximal renal arteries produced a sustained decease in sympathetic activity and BP without changes in sodium/water excretion or activity of the systemic/renal renin-angiotensin system.
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Affiliation(s)
- Juan Gao
- The Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
- The Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | | | - Frank Smart
- The Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
- Department of Cardiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Akemi Katsurada
- The Department of Physiology and the Hypertension and Renal Center of Excellence, Tulane Health Sciences Center, New Orleans, Louisiana, USA
| | - Dale Seth
- The Department of Physiology and the Hypertension and Renal Center of Excellence, Tulane Health Sciences Center, New Orleans, Louisiana, USA
| | - L Gabriel Navar
- The Department of Physiology and the Hypertension and Renal Center of Excellence, Tulane Health Sciences Center, New Orleans, Louisiana, USA
| | - Daniel R Kapusta
- The Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
- The Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
- Department of Anesthesiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
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13
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Jiang D, Tokashiki M, Hayashi H, Kawagoe Y, Kuwasako K, Kitamura K, Kato J. Augmented Blood Pressure Variability in Hypertension Induced by Angiotensin II in Rats. Am J Hypertens 2016; 29:163-9. [PMID: 26112866 DOI: 10.1093/ajh/hpv102] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 06/05/2015] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Augmented blood pressure (BP) variability is associated with cardiovascular diseases in some clinical conditions including hypertension. Drugs that effectively reduce BP variability need to be identified, while few animal models are currently available to study BP variability. Here, we report that hypertension induced by continuous infusion of angiotensin II (Ang II) was accompanied by increased BP variability in rats. METHODS Ang II was subcutaneously infused at a rate of 240 pmol/kg/min into male Wistar rats undergoing intraperitoneal implantation of a transmitter connected to an abdominal aortic catheter. BP was continuously monitored via a telemetry system before and after the Ang II infusion in a conscious, unrestrained condition. BP variability was evaluated by coefficient of variation (CV) of BP levels measured every 15 minutes. In addition, spontaneously hypertensive and Wistar-Kyoto rats (SHR and WKY) were subjected to the BP monitoring experiment at 15 weeks of age. RESULTS Both systolic and diastolic BP levels were significantly elevated following the Ang II infusion. Similarly, CVs of systolic and diastolic BP in the Ang II infusion group were significantly higher than in the vehicle group upon 1 and 2 weeks of the infusion. Meanwhile, CVs of systolic and diastolic BP of SHR were in a range similar to those of WKY despite significantly higher BP than in WKY. CONCLUSIONS Hypertension induced by the continuous infusion of Ang II was accompanied by augmented BP variability in rats, an effect assumed to be at least in part, independent of BP elevation.
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Affiliation(s)
- Danfeng Jiang
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Mariko Tokashiki
- Department of Internal Medicine, University of Miyazaki Faculty of Medicine, Miyazaki, Japan
| | - Hidetaka Hayashi
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Yukiko Kawagoe
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Kenji Kuwasako
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Kazuo Kitamura
- Department of Internal Medicine, University of Miyazaki Faculty of Medicine, Miyazaki, Japan
| | - Johji Kato
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan;
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Ogier M, Bricca G, Bader M, Bezin L. Locus Coeruleus Dysfunction in Transgenic Rats with Low Brain Angiotensinogen. CNS Neurosci Ther 2016; 22:230-7. [PMID: 26775713 DOI: 10.1111/cns.12488] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 10/30/2015] [Accepted: 10/30/2015] [Indexed: 12/25/2022] Open
Abstract
AIMS Transgenic TGR(ASrAOGEN)680 (TGR) rats with specific downregulation of glial angiotensinogen (AOGEN) synthesis develop cardiovascular deficits, anxiety, altered response to stress, and depression. Here, we evaluated whether these deficits are associated with alteration of the integrity of the noradrenergic system originating from locus coeruleus (LC) neurons. METHODS Adult TGR rats were compared to control Sprague Dawley rats in terms of the following: tissue levels of transcripts encoding noradrenergic markers, tissue tyrosine hydroxylase (TH) protein level, in vivo TH activity, density of TH-containing fibers, behavioral response to novelty, locomotor activity, and polysomnography. RESULTS TH expression was increased in the LC of TGR rats compared to controls. In LC terminal fields, there was an increase in density of TH-containing fibers in TGR rats that was associated with an elevation of in vivo TH activity. TGR rats also displayed locomotor hyperactivity in response to novelty. Moreover, polysomnographic studies indicated that daily paradoxical sleep duration was increased in TGR rats and that the paradoxical sleep rebound triggered by total sleep deprivation was blunted in these rats. CONCLUSIONS Altogether, these results suggest that disruption of astroglial AOGEN synthesis leads to cardiovascular, cognitive, behavioral, and sleep disorders that might be partly due to LC dysfunction.
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Affiliation(s)
- Michael Ogier
- INSERM U1028, CNRS UMR5292, University Claude Bernard Lyon 1, Lyon Neuroscience Research Center, Team TIGER, Lyon, France.,Institute for Epilepsy, IDEE, Lyon, France.,French Armed Forces Biomedical Research Institute, Bretigny-sur-Orge, France
| | | | - Michael Bader
- Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany
| | - Laurent Bezin
- INSERM U1028, CNRS UMR5292, University Claude Bernard Lyon 1, Lyon Neuroscience Research Center, Team TIGER, Lyon, France.,Institute for Epilepsy, IDEE, Lyon, France
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15
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Early Training-Induced Reduction of Angiotensinogen in Autonomic Areas-The Main Effect of Exercise on Brain Renin-Angiotensin System in Hypertensive Rats. PLoS One 2015; 10:e0137395. [PMID: 26372108 PMCID: PMC4570767 DOI: 10.1371/journal.pone.0137395] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 08/17/2015] [Indexed: 02/03/2023] Open
Abstract
Background Exercise training (T) blunts functional deficits and renin-angiotensin system (RAS) hyperactivity in hypertensive individuals. There is no information on T-induced temporal changes of brain RAS. We evaluate now the simultaneous effects of T on functional responses and time course changes in the expression/activity of brain RAS components in autonomic cardiovascular-controlling areas. Methods and Results Spontaneously hypertensive rats (SHR) and age-matched normotensive controls (WKY) were trained for 0, 1, 2, 4, 8 and 12 weeks. Sedentary (S) groups served as time-controls. After arterial pressure (AP) and heart rate (HR) recordings at rest, fresh and fixed brains were harvested for qPCR and immunofluorescence assays. SHR-S vs. WKY-S exhibited higher mean AP (MAP) and HR, increased pressure variability and sympathetic activity, elevated AT1 receptor (AT1) expression in nucleus tractus solitarii (NTS) and higher Mas receptor expression in the rostroventrolateral medulla (RVLM). In SHR, T promptly (T2 on) reduced sympathetic variability to heart/vessels and largely decreased angiotensinogen expression in the paraventricular hypothalamic nucleus (PVN) and NTS, with a late RVLM reduction (T4). AT1 expression was only reduced at T12 (PVN and NTS) with transient, not maintained Mas receptor changes in PVN and RVLM. These responses were accompanied by baseline MAP and HR reduction in the SHR-T (from T4 on). In the SHR group, PVN angiotensinogen expression correlated positively with sympathetic activity, resting MAP and HR. In WKY-T, a precocious (T2-T12) RVLM AT1 decrease preceded the appearance of resting bradycardia (from T8 on). Conclusions Early and maintained reduction of angiotensinogen content in autonomic areas of the SHR is the most prominent effect of training on brain RAS. Down-regulation of PVN RAS expression is an essential factor to drive cardiovascular benefits in SHR-T, while resting bradycardia in WKY-T is correlated to RVLM AT1 reduction.
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16
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Pellegrino PR, Schiller AM, Zucker IH. Validation of pulse rate variability as a surrogate for heart rate variability in chronically instrumented rabbits. Am J Physiol Heart Circ Physiol 2014; 307:H97-109. [PMID: 24791786 DOI: 10.1152/ajpheart.00898.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Heart rate variability (HRV) is a function of cardiac autonomic tone that is widely used in both clinical and animal studies. In preclinical studies, HRV measures are frequently derived using the arterial pulse waveform from an implanted pressure telemetry device, termed pulse rate variability (PRV), instead of the electrocardiogram signal in accordance with clinical guidelines. The acceptability of PRV as a surrogate for HRV in instrumented animals is unknown. Using rabbits implanted with intracardiac leads and chronically implanted pressure transducers, we investigated the correlation and agreement of time-domain, frequency-domain, and nonlinear indexes of HRV and PRV at baseline. We also investigated the effects of ventricular pacing and autonomic blockade on both measures. At baseline, HRV and PRV time- and frequency-domain parameters showed robust correlations and moderate to high agreement, whereas nonlinear parameters showed slightly weaker correlations and varied agreement. Ventricular pacing almost completely eliminated HRV, and spectral analysis of the PRV signal revealed a HRV-independent rhythm. After cardiac autonomic blockade with atropine or metoprolol, the changes in time- and non-normalized frequency-domain measures of PRV continued to show strong correlations and moderate to high agreement with corresponding changes in HRV measures. Blockade-induced changes in nonlinear PRV indexes correlated poorly with HRV changes and showed weak agreement. These results suggest that time- and frequency-domain measures of PRV are acceptable surrogates for HRV even in the context of changing cardiac autonomic tone, but caution should be used when nonlinear measures are a primary end point or when HRV is very low as HRV-independent rhythms may predominate.
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Affiliation(s)
- Peter R Pellegrino
- Department of Cellular and Integrative Physiology, The University of Nebraska Medical Center, Omaha, Nebraska
| | - Alicia M Schiller
- Department of Cellular and Integrative Physiology, The University of Nebraska Medical Center, Omaha, Nebraska
| | - Irving H Zucker
- Department of Cellular and Integrative Physiology, The University of Nebraska Medical Center, Omaha, Nebraska
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Campos LA, Pereira VL, Muralikrishna A, Albarwani S, Brás S, Gouveia S. Mathematical biomarkers for the autonomic regulation of cardiovascular system. Front Physiol 2013; 4:279. [PMID: 24109456 PMCID: PMC3791874 DOI: 10.3389/fphys.2013.00279] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 09/17/2013] [Indexed: 01/29/2023] Open
Abstract
Heart rate and blood pressure are the most important vital signs in diagnosing disease. Both heart rate and blood pressure are characterized by a high degree of short term variability from moment to moment, medium term over the normal day and night as well as in the very long term over months to years. The study of new mathematical algorithms to evaluate the variability of these cardiovascular parameters has a high potential in the development of new methods for early detection of cardiovascular disease, to establish differential diagnosis with possible therapeutic consequences. The autonomic nervous system is a major player in the general adaptive reaction to stress and disease. The quantitative prediction of the autonomic interactions in multiple control loops pathways of cardiovascular system is directly applicable to clinical situations. Exploration of new multimodal analytical techniques for the variability of cardiovascular system may detect new approaches for deterministic parameter identification. A multimodal analysis of cardiovascular signals can be studied by evaluating their amplitudes, phases, time domain patterns, and sensitivity to imposed stimuli, i.e., drugs blocking the autonomic system. The causal effects, gains, and dynamic relationships may be studied through dynamical fuzzy logic models, such as the discrete-time model and discrete-event model. We expect an increase in accuracy of modeling and a better estimation of the heart rate and blood pressure time series, which could be of benefit for intelligent patient monitoring. We foresee that identifying quantitative mathematical biomarkers for autonomic nervous system will allow individual therapy adjustments to aim at the most favorable sympathetic-parasympathetic balance.
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Affiliation(s)
- Luciana A Campos
- Center of Innovation, Technology and Education-(CITE), Camilo Castelo Branco University (UNICASTELO) Sao Jose dos Campos, Brazil
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Herichová I, Šoltésová D, Szántóová K, Mravec B, Neupauerová D, Veselá A, Zeman M. Effect of angiotensin II on rhythmic per2 expression in the suprachiasmatic nucleus and heart and daily rhythm of activity in Wistar rats. ACTA ACUST UNITED AC 2013; 186:49-56. [PMID: 23850797 DOI: 10.1016/j.regpep.2013.06.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 04/29/2013] [Accepted: 06/27/2013] [Indexed: 11/26/2022]
Abstract
Endogenous daily rhythms are generated by the hierarchically organized circadian system predominantly synchronized by the external light (L): dark (D) cycle. During recent years several humoral signals have been found to influence the generation and manifestation of daily rhythm. Since most studies have been performed under in vitro conditions, the mechanisms employed under in vivo conditions need to be investigated. Our study focused on angiotensin II (angII)-mediated regulation of Per2 expression in the suprachiasmatic nuclei (SCN) and heart and spontaneous locomotor activity in Wistar rats under synchronized conditions. Angiotensin II was infused (100ng/kg/min) via subcutaneously implanted osmotic minipumps for 7 or 28days. Samples were taken in 4-h intervals during a 24hcycle and after a light pulse applied in the first and second part of the dark phase. Gene expression was measured using real time PCR. Locomotor activity was monitored using an infrared camera with a remote control installed in the animal facility. Seven days of angII infusion caused an increase in blood pressure and heart/body weight index and 28days of angII infusion also increased water intake in comparison with controls. We observed a distinct daily rhythm in Per2 expression in the SCN and heart of control rats and infused rats. Seven days of angII infusion did not influence Per2 expression in the heart. 28days of angII treatment caused significant phase advance and a decrease in nighttime expression of Per2 and influenced expression of clock controlled genes Rev-erb alpha and Dbp in the heart compared to the control. Four weeks of angII infusion decreased the responsiveness of Per2 expression in the SCN to a light pulse at the end of the dark phase of the 24hcycle. Expression of mRNA coding angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2) showed a daily rhythm in the heart of control rats. Four weeks of angII infusion caused a decrease in amplitude of rhythmic expression of Ace, the disappearance of rhythm and an increase in Ace2 expression. The Ace/Ace2 ratio showed a rhythmic pattern in the heart of control rats with peak levels during the dark phase. Angiotensin II infusion decreased the mean Ace/Ace2 mRNA ratio in the heart. We observed a significant daily rhythm in expression of brain natriuretic peptide (BNP) in the heart of control rats. In hypertensive rats mean value of Bnp expression increased. Locomotor activity showed a distinct daily rhythm in both groups. Angiotensin II time dependently decreased ratio of locomotor activity in active versus passive phase of 24hcycle. To conclude, 28days of subcutaneous infusion of angII modulates the functioning of the central and peripheral circadian system measured at the level of Per2 expression and locomotor activity.
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Affiliation(s)
- Iveta Herichová
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Mlynská dolina B-2, 842 15 Bratislava, Slovak Republic.
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Effects of chronotherapy of benazepril on the diurnal profile of RAAS and clock genes in the kidney of 5/6 nephrectomy rats. ACTA ACUST UNITED AC 2013; 33:368-374. [PMID: 23771662 DOI: 10.1007/s11596-013-1126-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Indexed: 10/26/2022]
Abstract
This study investigated the effects of benazepril administered in the morning or evening on the diurnal variation of renin-angiotensin-aldosterone system (RAAS) and clock genes in the kidney. The male Wistar rat models of 5/6 subtotal nephrectomy (STNx) were established. Animals were randomly divided into 4 groups: sham STNx group (control), STNx group, morning benazepril group (MB) and evening benazepril group (EB). Benazepril was intragastrically administered at a dose of 10 mg/kg/day at 07:00 and 19:00 in the MB group and EB group respectively for 12 weeks. All the animals were synchronized to the light:dark cycle of 12:12 for 12 weeks. Systolic blood pressure (SBP), 24-h urinary protein excretion and renal function were measured at 11 weeks. Blood samples and kidneys were collected every 4 h throughout a day to detect the expression pattern of renin activity (RA), angiotensin II (AngII) and aldosterone (Ald) by radioimmunoassay (RIA) and the mRNA expression profile of clock genes (bmal1, dbp and per2) by real-time PCR at 12 weeks. Our results showed that no significant differences were noted in the SBP, 24-h urine protein excretion and renal function between the MB and EB groups. There were no significant differences in average Ald and RA content of a day between the MB group and EB group. The expression peak of bmal1 mRNA was phase-delayed by 4 to 8 h, and the diurnal variation of per2 and dbp mRNA diminished in the MB and EB groups compared with the control and STNx groups. It was concluded when the similar SBP reduction, RAAS inhibition and clock gene profile were achieved with optimal dose of benazepril, morning versus evening dosing of benazepril has the same renoprotection effects.
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Campos LA, Cipolla-Neto J, Amaral FG, Michelini LC, Bader M, Baltatu OC. The Angiotensin-melatonin axis. Int J Hypertens 2013; 2013:521783. [PMID: 23365722 PMCID: PMC3556444 DOI: 10.1155/2013/521783] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 12/18/2012] [Accepted: 12/19/2012] [Indexed: 12/14/2022] Open
Abstract
Accumulating evidence indicates that various biological and neuroendocrine circadian rhythms may be disrupted in cardiovascular and metabolic disorders. These circadian alterations may contribute to the progression of disease. Our studies direct to an important role of angiotensin II and melatonin in the modulation of circadian rhythms. The brain renin-angiotensin system (RAS) may modulate melatonin synthesis, a hormone with well-established roles in regulating circadian rhythms. Angiotensin production in the central nervous system may not only influence hypertension but also appears to affect the circadian rhythm of blood pressure. Drugs acting on RAS have been proven effective in the treatment of cardiovascular and metabolic disorders including hypertension and diabetes mellitus (DM). On the other hand, since melatonin is capable of ameliorating metabolic abnormalities in DM and insulin resistance, the beneficial effects of RAS blockade could be improved through combined RAS blocker and melatonin therapy. Contemporary research is evidencing the existence of specific clock genes forming central and peripheral clocks governing circadian rhythms. Further research on the interaction between these two neurohormones and the clock genes governing circadian clocks may progress our understanding on the pathophysiology of disease with possible impact on chronotherapeutic strategies.
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Affiliation(s)
- Luciana A. Campos
- Center of Innovation, Technology and Education—(CITE), Camilo Castelo Branco University (UNICASTELO), São José dos Campos Technology Park, Presidente Dutra Road Km 138, 12247-004 São José dos Campos, SP, Brazil
| | - Jose Cipolla-Neto
- Department of Physiology, Institute of Biomedical Sciences, University of São Paulo, 05508-000 São Paulo, SP, Brazil
| | - Fernanda G. Amaral
- Department of Physiology, Institute of Biomedical Sciences, University of São Paulo, 05508-000 São Paulo, SP, Brazil
| | - Lisete C. Michelini
- Department of Physiology, Institute of Biomedical Sciences, University of São Paulo, 05508-000 São Paulo, SP, Brazil
| | - Michael Bader
- Cardiovascular Research, Max Delbruck Center for Molecular Medicine, 13125 Berlin, Germany
| | - Ovidiu C. Baltatu
- Center of Innovation, Technology and Education—(CITE), Camilo Castelo Branco University (UNICASTELO), São José dos Campos Technology Park, Presidente Dutra Road Km 138, 12247-004 São José dos Campos, SP, Brazil
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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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Moniwa N, Varagic J, Ahmad S, VonCannon JL, Ferrario CM. Restoration of the blood pressure circadian rhythm by direct renin inhibition and blockade of angiotensin II receptors in mRen2.Lewis hypertensive rats. Ther Adv Cardiovasc Dis 2012; 6:15-29. [PMID: 22222314 DOI: 10.1177/1753944711434039] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Alterations in the circadian arterial pressure rhythm predict cardiovascular mortality. We examined the circadian arterial pressure rhythm and the effect of renin-angiotensin system blockade in congenic mRen2.Lewis hypertensive rats, a renin-dependent model of hypertension derived from the backcross of transgenic hypertensive [mRen-2]27 rats with Lewis normotensive ones. METHODS Twenty-nine mRen2.Lewis hypertensive rats were randomly assigned to drink tap water (vehicle; n = 9), valsartan (30 mg/kg/day; n = 10), or valsartan (30 mg/kg/day) combined with aliskiren given subcutaneously (50 mg/kg/day; n = 10) for 2 weeks. Arterial pressure, heart rate, and locomotive activity were recorded with chronically implanted radiotelemetry probes. The awake/asleep ratio was calculated as [awake mean arterial pressure (MAP) mean - asleep MAP mean)] / (awake MAP mean) x 100. Plasma renin activity (PRA) and concentration (PRC), and plasma and kidney angiotensin II (Ang II) were measured by radioimmunoassay (RIAs). RESULTS Untreated hypertensive rats showed an inverse arterial pressure rhythm, higher at day and lower at night, accompanied by normal rhythms of heart rate and locomotive activity. Treatment with valsartan or aliskiren and valsartan normalized the elevated arterial pressure and the arterial pressure rhythm, with the combination therapy being more effective in reducing MAP and in restoring the awake/asleep ratio. While PRA and PRC increased with the treatments, the addition of aliskiren to valsartan partially reversed the increases in plasma Ang II levels. Valsartan and the aliskiren and valsartan combination markedly reduced the renal cortical content of Ang II. CONCLUSION The altered circadian arterial pressure rhythm in this renin-dependent hypertension model uncovers a significant role of Ang II in the desynchronization of the circadian rhythm of arterial pressure, heart rate, and locomotive activity.
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Affiliation(s)
- Norihito Moniwa
- Division of Surgical Sciences, Wake Forest University School of Medicine, Winston Salem, NC 27157, USA.
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Baltatu OC, Campos LA, Bader M. Local renin-angiotensin system and the brain--a continuous quest for knowledge. Peptides 2011; 32:1083-6. [PMID: 21333703 DOI: 10.1016/j.peptides.2011.02.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 02/10/2011] [Indexed: 01/22/2023]
Abstract
The ancient renin-angiotensin system (RAS) was discovered more than a hundred years ago by identifying the rate-limiting enzyme of the system and its relevance to blood pressure regulation. Forty years ago, Detlev Ganten et al. postulated the existence of a tissue RAS. In these forty years, he kept developing the knowledge of these systems either directly or by training or attracting the interest of many researchers. Through the present review, we try to highlight recent advancements that originated from the postulation of local brain RAS. Although a large amount of knowledge accumulated, this system continues to intrigue and stimulate the interest and imagination of many researchers.
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Affiliation(s)
- Ovidiu C Baltatu
- Center of Biomedical Engineering, University Camilo Castelo Branco, Rod. Presidente Dutra Km 138, SP, 12247-004 São José dos Campos, Brazil
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Hypertensive effects of central angiotensin II infusion and restraint stress are reduced with age. J Hypertens 2010; 28:1298-306. [PMID: 20308921 DOI: 10.1097/hjh.0b013e328338a075] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE We investigated the effect of age on cardiovascular responses mediated by central angiotensin II (AngII) after intracerebroventricular infusion of AngII, and during restraint stress. METHODS Blood pressure (BP) and heart rate (HR) of young (5-month-old) and old (27-month-old) male Fischer-344 x Brown-Norway rats were measured using radiotelemetry. AngII was infused intracerebroventricularly using osmotic minipumps (10 ng/0.5 microl/h for 11 days). BP and HR responses to stress were evaluated by placing animals in restrainers for 20 min before and after intracerebroventricular infusion of the AngII-type-1 receptor inhibitor losartan (15 microg/microl per h for 3 days). RESULTS Resting BP was significantly elevated and HR was significantly lower in old rats compared with young. AngII-induced BP increase was markedly reduced in old rats, but HR responses were similar. Diurnal variation of both BP and HR was lower in old animals, and AngII reduced the amplitude of BP variation in young rats, but not in old. Restraint stress-induced BP and HR elevations were reduced with age. BP responses were diminished by central losartan infusion in both young and old, but this effect was more significant in young rats. In addition, expression of CuZn-superoxide dismutase and catalase declined significantly with age in the hypothalamus, whereas baseline oxidative stress increased. In contrast, AngII-induced increase in hypothalamic oxidative stress decreased with age. CONCLUSION This study demonstrates that the role of central AngII diminishes with age in the regulation of BP both during baseline conditions and during stress, whereas the involvement of AngII in the regulation of HR remains unaffected.
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Bader M. Tissue renin-angiotensin-aldosterone systems: Targets for pharmacological therapy. Annu Rev Pharmacol Toxicol 2010; 50:439-65. [PMID: 20055710 DOI: 10.1146/annurev.pharmtox.010909.105610] [Citation(s) in RCA: 231] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The renin-angiotensin-aldosterone system is one of the most important systems in cardiovascular control and in the pathogenesis of cardiovascular diseases. Therefore, it is already a very successful drug target for the therapy of these diseases. However, angiotensins are generated not only in the plasma but also locally in tissues from precursors and substrates either locally expressed or imported from the circulation. In most areas of the brain, only locally generated angiotensins can exert effects on their receptors owing to the blood-brain barrier. Other tissue renin-angiotensin-aldosterone systems are found in cardiovascular organs such as kidney, heart, and vessels and play important roles in the function of these organs and in the deleterious actions of hypertension and diabetes on these tissues. Novel components with mostly opposite actions to the classical renin-angiotensin-aldosterone systems have been described and need functional characterization to evaluate their suitability as novel drug targets.
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Affiliation(s)
- Michael Bader
- Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany.
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Chen D, Hazelwood L, Walker LL, Oldfield BJ, McKinley MJ, Allen AM. Changes in angiotensin type 1 receptor binding and angiotensin-induced pressor responses in the rostral ventrolateral medulla of angiotensinogen knockout mice. Am J Physiol Regul Integr Comp Physiol 2010; 298:R411-8. [DOI: 10.1152/ajpregu.00462.2009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
ANG II, the main circulating effector hormone of the renin-angiotensin system, is produced by enzymatic cleavage of angiotensinogen. The present study aimed to examine whether targeted deletion of the angiotensinogen gene ( Agt) altered brain ANG II receptor density or responsiveness to ANG II. In vitro autoradiography was used to examine the distribution and density of angiotensin type 1 (AT1) and type 2 receptors. In most brain regions, the distribution and density of angiotensin receptors were similar in brains of Agt knockout mice ( Agt−/−) and wild-type mice. In Agt−/−mice, a small increase in AT1receptor binding was observed in the rostral ventrolateral medulla (RVLM), a region that plays a critical role in blood pressure regulation. To examine whether Agt−/−mice showed altered responses to ANG II, blood pressure responses to intravenous injection (0.01–0.1 μg/kg) or RVLM microinjection (50 pmol in 50 nl) of ANG II were recorded in anesthetized Agt−/−and wild-type mice. Intravenous injections of phenylephrine (4 μg/kg and 2 μg/kg) were also made in both groups. The magnitude of the pressor response to intravenous injections of ANG II or phenylephrine was not different between Agt−/−and wild-type mice. Microinjection of ANG II into the RVLM induced a pressor response, which was significantly smaller in Agt−/−compared with wild-type mice (+10 ± 1 vs. +23 ± 4 mmHg, respectively, P = 0.004). Microinjection of glutamate into the RVLM (100 pmol in 10 nl) produced a robust pressor response, which was not different between Agt−/−and wild-type mice. A diminished response to ANG II microinjection in the RVLM of Agt−/−mice, despite an increased density of AT1receptors suggests that signal transduction pathways may be altered in RVLM neurons of Agt−/−mice, resulting in attenuated cellular excitation.
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Affiliation(s)
- Daian Chen
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Lisa Hazelwood
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Lesley L. Walker
- Howard Florey Institute, Florey Neurosciences Institutes, University of Melbourne, Victoria, Australia; and
| | | | - Michael J. McKinley
- Department of Physiology, University of Melbourne, Victoria, Australia
- Howard Florey Institute, Florey Neurosciences Institutes, University of Melbourne, Victoria, Australia; and
| | - Andrew M. Allen
- Department of Physiology, University of Melbourne, Victoria, Australia
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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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Ibrahim J, Berk BC, Hughes AD. Comparison of Simultaneous Measurements of Blood Pressure by Tail-Cuff and Carotid Arterial Methods in Conscious Spontaneously Hypertensive and Wistar-Kyoto Rats. Clin Exp Hypertens 2009; 28:57-72. [PMID: 16443565 DOI: 10.1080/10641960500386817] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
We determined the validity of systolic blood pressure (SBP) measured by tail-cuff blood pressure (TCBP) with direct intra-arterial measurements. In conscious, restrained Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR), carotid artery (CA) BP and TCBP were simultaneously measured. In both WKY and SHR strains, highly significant correlations between CABP and TCBP were found and Bland-Altman analyses showed no bias when the two methods were compared. The limits of agreement between CABP and TCBP in WKY and SHR were wide and reproducibility of pressure measurements by either technique was poor, with some evidence for strain-dependent differences. Pressure measurements made over short time frames, however, showed close agreement between CABP and TCBP. Acetylcholine-induced reductions in pressure were equivalently detected by tail-cuff and direct arterial measurement in both strains but angiotensin II-induced pressure elevations were over-estimated by tail-cuff in SHR. Telemetered SBP measurements in conscious rats were highly variable in a strain-dependent manner.
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Affiliation(s)
- Jamila Ibrahim
- Clinical Pharmacology, NHLI Division, Faculty of Medicine, Imperial College of Medicine, London, UK.
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Son YJ, Yun CH, Kim JG, Park JW, Kim JH, Kang SG, Lee BJ. Expression and role of TTF-1 in the rat suprachiasmatic nucleus. Biochem Biophys Res Commun 2009; 380:559-63. [PMID: 19285000 DOI: 10.1016/j.bbrc.2009.01.119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Accepted: 01/22/2009] [Indexed: 10/21/2022]
Abstract
We have previously reported that TTF-1, a homeodomain-containing transcription factor, regulates circadian rhythm of pituitary adenylate cyclase-activating polypeptide gene expression in the rat hypothalamus. In this study we found that TTF-1 mRNA was specifically expressed in the rat suprachiasmatic nucleus (SCN) and colocalized with Period 2 (Per2), a circadian feedback loop controller. Interaction between TTF-1 and Per1 and Per2 was demonstrated by immunoprecipitation and immunoblot assays. Moreover, TTF-1 and Per proteins additively stimulated a transcriptional activity of angiotensinogen (AoGen) gene. TTF-1 also activated in vitro rhythm of AoGen transcription determined by secretary alkaline phosphatase (SEAP) reporter system in the NIH3T3 cells. These results suggest that TTF-1 plays a role in the circadian rhythm regulation of the AoGen gene expression via interacting with Per proteins in the rat SCN.
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Affiliation(s)
- Young June Son
- Department of Biological Sciences, College of Natural Sciences, University of Ulsan, San29, Mugeodong, Namgu, Ulsan 680-749, South Korea
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Carlson SH, Wyss JM. Neurohormonal regulation of the sympathetic nervous system: new insights into central mechanisms of action. Curr Hypertens Rep 2009; 10:233-40. [PMID: 18765096 DOI: 10.1007/s11906-008-0044-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
To regulate blood pressure, the brain controls circulating hormones, which influence the brain by binding to brain neurons that lie outside the blood-brain barrier. Recent work has demonstrated that "cardiovascular" hormones are synthesized and released in the brain as neurotransmitters/neuromodulators and can, in some cases, signal through the blood-brain barrier. The renin-angiotensin system is a prototype for these newly appreciated mechanisms. The brain's intrinsic renin-angiotensin system plays an important role in blood pressure control. Angiotensin II in brain neurons affects other neurons both through activation of angiotensin receptors and via generation of nitric oxide and reactive oxygen molecules. Similarly, angiotensin in blood vessels activates endothelial nitric oxide, which can diffuse across the blood-brain barrier and thereby alter neuronal activity in cardiovascular control nuclei. The relative importance of these mechanisms to blood pressure control remains to be fully elucidated.
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Affiliation(s)
- Scott H Carlson
- Department of Cell Biology, University of Alabama at Birmingham, 1900 University Boulevard, THT 950, Birmingham, AL 35294, USA
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Sampson AK, Widdop RE, Denton KM. Sex-differences in circadian blood pressure variations in response to chronic angiotensin II infusion in rats. Clin Exp Pharmacol Physiol 2008; 35:391-5. [PMID: 18307727 DOI: 10.1111/j.1440-1681.2008.04884.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. The aim of this study was to investigate the effect of chronic angiotensin II (AngII) infusion on the circadian rhythms of arterial blood pressure, heart rate (HR) and locomotor activity (ACT) in male and female rats. 2. Radiotelemetry probes were implanted into the aorta in male and female rats and allowed 10 days for recovery. Control levels for mean arterial pressure (MAP), HR and ACT were recorded for 3 days, then AngII (400 ng/kg per min s.c. via osmotic minipump) or vehicle (saline) was infused for 10 days (n = 6 per group). Further recordings of MAP, HR and ACT were made during days 8, 9 and 10 of the infusion period. 3. In response to AngII infusion, night and day-time MAP increased significantly in female (18 +/- 2 mmHg; 28 +/- 7 mmHg) and male (27 +/- 4 mmHg; 30 +/- 3 mmHg) rats, respectively. The degree of elevation in MAP in response to AngII was attenuated in the females during the night period (P(sex) < 0.05) but not the day (P(sex) = 0.2). Control night-day differences in MAP, HR and ACT averaged 7 +/- 1 mmHg, 58 +/- 5 b.p.m. and 30 +/- 4 units in the female and 6 +/- 1 mmHg, 43 +/- 3 b.p.m. (P(sex) < 0.05) and 14 +/- 2 units (P(sex) < 0.05) in male rats, respectively. AngII infusion disrupted MAP circadian rhythm in female (-4 +/- 2 mmHg) and male rats (1 +/- 2 mmHg; P(treat) < 0.01), but did not affect heart rate or locomotor activity. 4. In conclusion, sex differences in the circadian rhythm of heart rate and locomotor activity, but not arterial pressure exist under basal conditions. Circulating AngII modulated the circadian rhythm of MAP in female and male rats but not heart rate or locomotor activity. These findings have important implications for our understanding of circadian blood pressure rhythms in states of activation of the renin angiotensin system.
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Affiliation(s)
- Amanda K Sampson
- Department of Physiology, Monash University, Melbourne, Victoria, Australia
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33
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Bader M, Ganten D. Update on tissue renin-angiotensin systems. J Mol Med (Berl) 2008; 86:615-21. [PMID: 18414822 DOI: 10.1007/s00109-008-0336-0] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Revised: 02/26/2008] [Accepted: 02/27/2008] [Indexed: 12/15/2022]
Abstract
Angiotensin (Ang) II is not only generated in the circulation by renin and angiotensin-converting enzyme (ACE) but also is produced locally in numerous organs including kidney, vessels, heart, adrenal gland, eye, testis, and brain. Furthermore, widely distributed mast cells have been shown to be a production site. Local Ang II production process is commonly termed the result of a "tissue" renin-angiotensin system (RAS). Because pharmacological experiments do not easily allow targeting of specific tissues, many novel findings about the functional importance of tissue RAS have been collected from transgenic rodent models. These animals either overexpress or lack RAS components in specific tissues and thereby elucidate their local functions. The data to date show that in most tissues local RAS amplify the actions of circulating Ang II with important implications for physiology and pathophysiology of cardiovascular diseases. This review summarizes the recent findings on the importance of tissue RAS in the most relevant cardiovascular organs.
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Affiliation(s)
- Michael Bader
- Max-Delbrück-Centrum for Molecular Medicine (MDC), Berlin, Germany.
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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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35
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Parrish DC, Gritman K, Van Winkle DM, Woodward WR, Bader M, Habecker BA. Postinfarct sympathetic hyperactivity differentially stimulates expression of tyrosine hydroxylase and norepinephrine transporter. Am J Physiol Heart Circ Physiol 2008; 294:H99-H106. [DOI: 10.1152/ajpheart.00533.2007] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The balance between norepinephrine (NE) synthesis, release, and reuptake is disrupted after acute myocardial infarction, resulting in elevated extracellular NE. Stimulation of sympathetic neurons in vitro increases NE synthesis and the synthetic enzyme tyrosine hydroxylase (TH) to a greater extent than it increases NE reuptake and the NE transporter (NET), which removes NE from the extracellular space. We used TGR(ASrAOGEN) transgenic rats, which lack postinfarct sympathetic hyperactivity, to test the hypothesis that increased cardiac sympathetic nerve activity accounts for the imbalance in TH and NET expression in these neurons after myocardial infarction. TH and NET mRNA levels were identical in the stellate ganglia of unoperated TGR(ASrAOGEN) rats compared with Sprague Dawley (SD) controls, but the threefold increase in TH and twofold increase in NET mRNA seen in the stellate ganglia of SD rats 1 wk after ischemia-reperfusion was absent in TGR(ASrAOGEN) rats. Similarly, the increase in TH and NET protein observed in the base of the SD ventricle was absent in the base of the TGR (ASrAOGEN) ventricle. Neuronal TH content was depleted in the left ventricle of both genotypes, whereas NET was unchanged. Basal heart rate and cardiac function were similar in both genotypes, but TGR(ASrAOGEN) hearts were more sensitive to the β-agonist dobutamine. Tyramine-induced release of endogenous NE generated similar changes in ventricular pressure and contractility in both genotypes, but postinfarct relaxation was enhanced in TGR(ASrAOGEN) hearts. These data support the hypothesis that postinfarct sympathetic hyperactivity is the major stimulus increasing TH and NET expression in cardiac neurons.
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Monosíková J, Herichová I, Mravec B, Kiss A, Zeman M. Effect of upregulated renin–angiotensin system on per2 and bmal1 gene expression in brain structures involved in blood pressure control in TGR(mREN-2)27 rats. Brain Res 2007; 1180:29-38. [PMID: 17915197 DOI: 10.1016/j.brainres.2007.08.061] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Revised: 07/20/2007] [Accepted: 08/24/2007] [Indexed: 11/22/2022]
Abstract
Circadian system regulates rhythms with 24 h period including those occurring in the cardiovascular system. Inverted blood pressure profile was demonstrated in hypertensive TGR(mREN-2)27 (TGR) rats with upregulated renin-angiotensin system. To depict structures involved in the generation of the inverted pattern of blood pressure in TGR rats, we analyzed daily expression of clock genes per2 and bmal1 in the brain areas involved in the regulation of the blood pressure. Heterozygous male TGR and control rats were synchronized to the light:dark cycle 12:12 and blood samples were taken in 4 h intervals within 24 h cycle. The levels of the plasma renin activity were increased in TGR rats in comparison with controls. Brain nuclei were isolated by dissection from frozen sections. The clock gene expression was determined in the hypothalamic paraventricular and dorsomedial nuclei, dorsal vagal motor nucleus, caudal ventrolateral medulla, nucleus ambiguus, area postrema, and anteroventral third ventricle. Daily pattern of per2 expression was rhythmic in most of the nuclei studied with its highest levels at the beginning of the nighttime in both groups of rats. Expression of bmal1 peaked at the beginning of the day. We found robust differences in the clock gene expression between the TGR and control rats in the area postrema. TGR rats exerted changes in the clock gene expression in the nucleus ambiguus which receives direct innervation from the area postrema. The area postrema seems to play a key role in the transmission of signals from the periphery to the CNS.
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Affiliation(s)
- Jana Monosíková
- Department of Animal Physiology and Ethology, Comenius University Bratislava, Mlynská dolina B2, 842 15 Bratislava, Slovak Republic
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Wessel N, Malberg H, Heringer-Walther S, Schultheiss HP, Walther T. The Angiotensin-(1-7) Receptor Agonist AVE0991 Dominates the Circadian Rhythm and Baroreflex in Spontaneously Hypertensive Rats. J Cardiovasc Pharmacol 2007; 49:67-73. [PMID: 17312445 DOI: 10.1097/fjc.0b013e31802cffe9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Because we previously suggested the endogenous heptapeptide angiotensin (Ang)-(1-7) to be involved in the improvement of baroreflex sensitivity observed in spontaneously hypertensive rats (SHR), we here investigated the role of the heptapeptide in blood pressure control under physiologic conditions in awake SHR using the first nonpeptide, orally applicable Ang-(1-7) receptor agonist AVE0991 by telemetry. Five weeks after the start of treatment the blood pressure signals (500 Hz) were monitored in 10 untreated and 6 age-matched male SHR treated by AVE0991 for 24 hours (every 2 hours for 10 minutes). The autonomous tone was estimated from the heart rate and blood pressure variability (HRV, BPV) and from the spontaneous baroreceptor sensitivity (BRS).AVE0991 treatment blunted the rodent-characterizing nightly increase in blood pressure and led to pronounced changes in the BPV and HRV parameters during the night in comparison to untreated controls (eg, sdNN: AVE0991=8.19 versus control=11.5 mm Hg; P<0.001). However, even more significant differences were detected for BRS. Whereas the average slope did not alter, the activation of the baroreflexes (P<10E-6) and the number of baroreflex fluctuations were reduced dramatically by AVE0991 (P<10E-5). The data obtained pointed to an abating impact of AVE0991 on the baroreceptor in SHR and to its influence on the circadian rhythm, thus implying a direct involvement of Ang-(1-7) in cardiovascular control.
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Affiliation(s)
- N Wessel
- Department of Physics, University of Potsdam, Germany
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Sakima A, Averill DB, Kasper SO, Jackson L, Ganten D, Ferrario CM, Gallagher PE, Diz DI. Baroreceptor reflex regulation in anesthetized transgenic rats with low glia-derived angiotensinogen. Am J Physiol Heart Circ Physiol 2006; 292:H1412-9. [PMID: 17085537 DOI: 10.1152/ajpheart.00984.2006] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endogenous angiotensin (ANG) II and ANG-(1-7) act at the nucleus tractus solitarius (NTS) to differentially modulate neural control of the circulation. The role of these peptides endogenous to NTS on cardiovascular reflex function was investigated in transgenic rats with low brain angiotensinogen (Aogen) due to glial overexpression of an antisense to Aogen (ASrAOGEN) and in Sprague-Dawley (SD) rats. Arterial baroreceptor reflex sensitivity (BRS) for control of heart rate (HR) in response to increases in mean arterial pressure (MAP) was tested before and after bilateral microinjection of the angiotensin type 1 (AT(1)) receptor blocker candesartan or the ANG-(1-7) receptor blocker (d-Ala(7))-ANG-(1-7) into the NTS of urethane-chloralose-anesthetized ASrAOGEN and SD rats. Baseline MAP was higher in ASrAOGEN than in SD rats under anesthesia (P < 0.01). Injection of candesartan or (d-Ala(7))-ANG-(1-7) decreased MAP (P < 0.01) and HR (P < 0.05) in ASrAOGEN, but not SD, rats. The BRS at baseline was similar in ASrAOGEN and SD rats. Candesartan increased BRS by 41% in SD rats (P < 0.01) but was without effect in ASrAOGEN rats. In contrast, the reduction in BRS after (d-Ala(7))-ANG-(1-7) administration was comparable in SD (31%) and ASrAOGEN rats (34%). These findings indicate that the absence of glia-derived Aogen is associated with 1) an increase in MAP under anesthesia mediated via AT(1) and ANG-(1-7) receptors within the NTS, 2) the absence of an endogenous ANG II contribution to tonic inhibition of BRS, and 3) a continued contribution of endogenous ANG-(1-7) to tonic enhancement of BRS.
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Affiliation(s)
- Atsushi Sakima
- Hypertension & Vascular Disease Center, Wake Forest Univ School of Medicine, Winston-Salem, NC 27157-1032, USA
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Herichová I, Mravec B, Stebelová K, Krizanová O, Jurkovicová D, Kvetnanský R, Zeman M. Rhythmic clock gene expression in heart, kidney and some brain nuclei involved in blood pressure control in hypertensive TGR(mREN-2)27 rats. Mol Cell Biochem 2006; 296:25-34. [PMID: 16909304 DOI: 10.1007/s11010-006-9294-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Accepted: 07/24/2006] [Indexed: 11/25/2022]
Abstract
Hypertensive TGR(mREN-2)27 rats exerting inverted blood pressure (BP) profile were used to study clock gene expression in structures responsible for BP control. TGR and control Sprague Dawley male rats were synchronized to the light:dark cycle 12:12 with food and water ad libitum. Daily rhythm in per2, bmal1, clock and dbp expression in the suprachiasmatic nucleus (SCN), rostral ventrolateral medulla (RVLM), nucleus of the solitary tract (NTS), heart and kidney was determined in both groups. Sampling occurred in regular 4 h intervals when rats of both strains were 11-weeks-old. Blood pressure and relative heart weight were significantly elevated in TGR rats in comparison with control. Expression of bmal1 and clock was up regulated in SCN of TGR rats but daily rhythm in per2 and dbp expression was similar in both groups. Mesor of per2 expression in RVLM was significantly higher in TGR than in control rats. In NTS of TGR rats expression of per2 was phase delayed by 3.5 h in comparison with control and bmal1 did not exert rhythmic pattern. Our study provided the first evidence about modified function of central and peripheral circadian oscillators in TGR rats at the level of clock gene expression. Expression of clock genes exerted up regulation in SCN and RVLM and down regulation in NTS. Circadian oscillators in selected brain structures were influenced more than oscillators in the heart and kidney by additional renin gene. Interactions of RAS and circadian system probably contribute to the development of inverted BP profile in TGR rats.
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Affiliation(s)
- Iveta Herichová
- Department of Animal Physiology and Ethology, Comenius University Bratislava, Mlynská dolina B2, 842 15, Bratislava, Slovak Republic
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Chen Y, Oroszi TL, Morris M. Salt consumption increases blood pressure and abolishes the light/dark rhythm in angiotensin AT1a receptor deficient mice. Physiol Behav 2006; 88:95-100. [PMID: 16643970 DOI: 10.1016/j.physbeh.2006.03.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 02/23/2006] [Accepted: 03/08/2006] [Indexed: 11/20/2022]
Abstract
Experiments were performed to study the role of angiotensin (Ang) AT1a receptors in dietary sodium-induced changes in blood pressure (BP). We measured light/dark rhythms in BP, heart rate (HR) and drinking behavior in Ang AT1a deficient (AT1a -/-) and wild type (AT1a +/+) mice with arterial telemetric catheters. Mice were given ad libitum access to a high salt diet (8% NaCl, HSD for 8 days) and tap water. The major finding was that the Ang AT1a -/- mice showed enhanced sodium sensitivity. This was seen by a greater percentage increase in BP (+21% vs. +12%) and an earlier onset of BP change (increase on day 5 vs. day 8) in AT1a -/- vs. AT1a +/+. The normal light/dark BP rhythm was abolished in AT1a -/- after 5 days of HSD. HSD produced an increase in water intake (drinking activity and volume consumed) in both groups with no difference in the percentage increase or the light/dark drinking rhythm. HSD produced no changes in plasma osmolality, hematocrit or body weight in either group. Evidence shows that a deficiency of Ang AT1a receptors results in an enhancement in sodium sensitivity along with a disruption of the normal light/dark BP rhythm. The data combined with previous findings suggests that activation of other components of the renin angiotensin system and/or sympathetic pathways may be responsible for the cardiovascular changes in AT1a deficient mice.
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Affiliation(s)
- Yanfang Chen
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University School, Dayton, OH 45450, USA.
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Campos LA, Iliescu R, Fontes MAP, Schlegel WP, Bader M, Baltatu OC. Enhanced isoproterenol-induced cardiac hypertrophy in transgenic rats with low brain angiotensinogen. Am J Physiol Heart Circ Physiol 2006; 291:H2371-6. [PMID: 16731636 DOI: 10.1152/ajpheart.01145.2005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously shown that a permanent deficiency in the brain renin-angiotensin system (RAS) may increase the sensitivity of the baroreflex control of heart rate. In this study we aimed at studying the involvement of the brain RAS in the cardiac reactivity to the beta-adrenoceptor (beta-AR) agonist isoproterenol (Iso). Transgenic rats with low brain angiotensinogen (TGR) were used. In isolated hearts, Iso induced a significantly greater increase in left ventricular (LV) pressure and maximal contraction (+dP/dt(max)) in the TGR than in the Sprague-Dawley (SD) rats. LV hypertrophy induced by Iso treatment was significantly higher in TGR than in SD rats (in g LV wt/100 g body wt, 0.28 +/- 0.004 vs. 0.24 +/- 0.004, respectively). The greater LV hypertrophy in TGR rats was associated with more pronounced downregulation of beta-AR and upregulation of LV beta-AR kinase-1 mRNA levels compared with those in SD rats. The decrease in the heart rate (HR) induced by the beta-AR antagonist metoprolol in conscious rats was significantly attenuated in TGR compared with SD rats (-9.9 +/- 1.7% vs. -18.1 +/- 1.5%), whereas the effect of parasympathetic blockade by atropine on HR was similar in both strains. These results indicate that TGR are more sensitive to beta-AR agonist-induced cardiac inotropic response and hypertrophy, possibly due to chronically low sympathetic outflow directed to the heart.
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Affiliation(s)
- Luciana A Campos
- Dept. of Physiology and Biophysics, The Center for Excellence in Cardiovascular-Renal Research, Univ. of Mississippi Medical Center, 2500 N. State St., Jackson, MS 39216-4505, USA
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Campos LA, Plehm R, Cipolla-Neto J, Bader M, Baltatu OC. Altered circadian rhythm reentrainment to light phase shifts in rats with low levels of brain angiotensinogen. Am J Physiol Regul Integr Comp Physiol 2006; 290:R1122-7. [PMID: 16339384 DOI: 10.1152/ajpregu.00703.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, we aimed to investigate the adaptation of blood pressure (BP), heart rate (HR), and locomotor activity (LA) circadian rhythms to light cycle shift in transgenic rats with a deficit in brain angiotensin [TGR(ASrAOGEN)]. BP, HR, and LA were measured by telemetry. After baseline recordings (bLD), the light cycle was inverted by prolonging the light by 12 h and thereafter the dark period by 12 h, resulting in inverted dark-light (DL) or light-dark (LD) cycles. Toward that end, a 24-h dark was maintained for 14 days (free-running conditions). When light cycle was changed from bLD to DL, the acrophases (peak time of curve fitting) of BP, HR, and LA shifted to the new dark period in both SD and TGR(ASrAOGEN) rats. However, the readjustment of the BP and HR acrophases in TGR(ASrAOGEN) rats occurred significantly slower than SD rats. The LA acrophases changed similarly in both strains. When light cycle was changed from DL to LD by prolonging the dark period by 12 h, the reentrainment of BP and LA occurred faster than the previous shift in both strains. The readjustment of the BP and HR acrophases in TGR(ASrAOGEN) rats occurred significantly slower than SD rats. In free-running conditions, the circadian rhythms of the investigated parameters adapted in TGR(ASrAOGEN) and SD rats in a similar manner. These results demonstrate that the brain RAS plays an important role in mediating the effects of light cycle shifts on the circadian variation of BP and HR. The adaptive behavior of cardiovascular circadian rhythms depends on the initial direction of light-dark changes.
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Affiliation(s)
- Luciana A Campos
- Max-Delbrück-Center for Molecular Medicine, Berlin-Buch, Germany
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da Silva Lemos M, Nardoni Gonçalves Braga A, Roberto da Silva J, Augusto Souza Dos Santos R. Altered cardiovascular responses to chronic angiotensin II infusion in aged rats. ACTA ACUST UNITED AC 2005; 132:67-73. [PMID: 16249039 DOI: 10.1016/j.regpep.2005.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2005] [Accepted: 09/08/2005] [Indexed: 11/20/2022]
Abstract
In this work we determined by telemetry the cardiovascular effects produced by Ang II infusion on blood pressure (BP) and heart rate (HR) in aged rats. Male Wistar aged (48-52 weeks) and young (12 weeks) rats were used. Ang II (6 microg/h, young, n=6; aged, n=6) or vehicle (0.9% NaCl 1 microl/h, young, n=4; aged, n=5) were infused subcutaneously for 7 days, using osmotic mini-pump. The basal diurnal and nocturnal BP values were higher in aged rats (day: 98+/-0.3 mm Hg, night: 104+/-0.4 mm Hg) than in the young rats (day: 92+/-0.2 mm Hg, night: 99+/-0.2 mm Hg). In contrast, the basal diurnal and nocturnal HR values were significantly smaller in the aged rats. Ang II infusion produced a greater increase in the diurnal BP in the aged rats (Delta MAP=37+/-1.8 mm Hg) compared to the young ones (Delta MAP=30+/-3.5 mm Hg). In contrast, the nocturnal MAP increase was similar in both groups (young rats; Delta MAP=22+/-3.0 mm Hg, aged rats; Delta MAP=24+/-2.6 mm Hg). During Ang II infusion HR decreased transiently in the young rats. An opposite trend was observed in the aged rats. Ang II infusion also inverted the BP circadian rhythm, in both groups. No changes in HR circadian rhythm were observed. These differences suggest that the aging process alters in a different way Ang II-sensitive neural pathways involved in the control of autonomic activity.
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Affiliation(s)
- Marisa da Silva Lemos
- Laboratório de Hipertensão, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas ICB-UFMG, Av. Antônio Carlos, 6627, Belo Horizonte, 31270-901, Belo Horizonte, MG, Brazil
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Iliescu R, Yanes LL, Bell W, Dwyer T, Baltatu OC, Reckelhoff JF. Role of the renal nerves in blood pressure in male and female SHR. Am J Physiol Regul Integr Comp Physiol 2005; 290:R341-4. [PMID: 16166211 DOI: 10.1152/ajpregu.00035.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Female spontaneously hypertensive rats (SHR) have lower blood pressures than males. The renin-angiotensin system plays an important role in the sexual dimorphism of blood pressure in SHR. The sympathetic nervous system can stimulate renin release, and, therefore, the present study was performed to determine whether the renal sympathetic nerves play a role in the sexual dimorphism of blood pressure in SHR. Male and female SHR underwent bilateral kidney denervation or sham surgery, and, 2 wk later, mean arterial pressure (MAP) and pulse interval were recorded, and baroreflex sensitivity (BRS) was measured by the sequence technique. Left ventricle index (LVI) was also calculated. MAP was higher in sham-operated males than females (182 +/- 5 vs. 169 +/- 4 mmHg; P < 0.01), but, despite the higher MAP in males, LVI was significantly greater in female rats. BRS was not different between sham-operated male and female SHR. Following bilateral renal denervation, MAP was decreased by a similar percentage (8-10%) in males (169 +/- 2 mmHg) and females (152 +/- 3 mmHg), whereas LVI was reduced only in female SHR. BRS was not altered by renal denervation in either sex. These data indicate that renal nerves play a role in the control of blood pressure in SHR independent of sex, but do not play a role in mediating the sex differences in blood pressure.
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Affiliation(s)
- Radu Iliescu
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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Abstract
Hypertension remains one of the largest human health problems, because hypertensive patients carry increased risk for ischemic heart disease, stroke, atherosclerosis, and renal failure. The renin-angiotensin system (RAS) has been intensively investigated for more than 100 years because it is a powerful regulator of blood pressure, and the antihypertensive benefits of RAS inhibitors are very clear. Despite a wealth of clinical and basic studies, the precise mechanisms by which the RAS regulates blood pressure remains incomplete. In this chapter, we review data demonstrating the existence and function of intrinsic tissue RAS, with a primary focus on the brain.
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Affiliation(s)
- Koji Sakai
- Departments of Internal Medicine and Physiology & Biophysics, 3181B Medical Education and Biomedical Research Facility, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 52242 Iowa City, IA USA
| | - Curt D. Sigmund
- Departments of Internal Medicine and Physiology & Biophysics, 3181B Medical Education and Biomedical Research Facility, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 52242 Iowa City, IA USA
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Sherrod M, Davis DR, Zhou X, Cassell MD, Sigmund CD. Glial-specific ablation of angiotensinogen lowers arterial pressure in renin and angiotensinogen transgenic mice. Am J Physiol Regul Integr Comp Physiol 2005; 289:R1763-9. [PMID: 16109805 DOI: 10.1152/ajpregu.00435.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Angiotensinogen (AGT) is mainly expressed in glial cells in close proximity to renin-expressing neurons in the brain. We previously reported that glial-specific overexpression of ANG II results in mild hypertension. Here, we tested the hypothesis that glial-derived AGT plays an important role in blood pressure regulation in hypertensive mice carrying human renin (hREN) and human AGT transgenes under the control of their own endogenous promoters. To perform a glial-specific deletion of AGT, we used an AGT transgene containing loxP sites (hAGT(flox)), so the gene can be permanently ablated in the presence of cre-recombinase expression, driven by the glial fibrillary acidic protein (GFAP) promoter. Triple transgenic mice (RAC) containing a: 1) systemically expressed hREN transgene, 2) systemically expressed hAGT(flox) transgene, and 3) GFAP-cre-recombinase were generated and compared with double transgenic mice (RA) lacking cre-recombinase. Liver and kidney hAGT mRNA levels were unaltered in RAC and RA mice, as was the level of hAGT in the systemic circulation, consistent with the absence of cre-recombinase expression in those tissues. Whereas hAGT mRNA was present in the brain of RA mice (lacking cre-recombinase), it was absent from the brain of RAC mice expressing cre-recombinase, confirming brain-specific elimination of AGT. Immunohistochemistry revealed a loss of AGT immunostaining glial cells throughout the brain in RAC mice. Arterial pressure measured by radiotelemetry was significantly lower in RAC than RA mice and unchanged from nontransgenic control mice. These data suggest that there is a major contribution of glial-AGT to the hypertensive state in mice carrying systemically expressed hREN and hAGT genes and confirm the importance of a glial source of ANG II substrate in the brain.
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Affiliation(s)
- Mikhiela Sherrod
- Genetics Graduate Program, Roy J. and Lucille A. Carver College of Medicine, Univ. of Iowa, Iowa City, Iowa 52242, USA
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Li G, Wang X, Abdel-Rahman AA. Brainstem norepinephrine neurons mediate ethanol-evoked pressor response but not baroreflex dysfunction. Alcohol Clin Exp Res 2005; 29:639-47. [PMID: 15834230 DOI: 10.1097/01.alc.0000160083.72579.ec] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Ethanol elicits strain-dependent blood pressure and baroreflex sensitivity responses in spontaneously hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats; the mechanisms underlying these divergent effects are not clear. The authors tested the hypothesis that differential neuronal actions of ethanol may account for these strain-dependent responses. To this end, the authors investigated the direct effects of ethanol on norepinephrine (NE)-containing neurons in the rostral ventrolateral medulla (RVLM), which modulate sympathetic neuronal activity, and on c-Jun-expressing neurons in the nucleus tractus solitarius (NTS), whose activity is inversely correlated with baroreflex sensitivity. METHODS In a newly developed model system in conscious, freely moving rats, the effect of intra-RVLM or intra-NTS ethanol was investigated on neuronal NE at the microinjection site (in vivo electrochemistry), blood pressure, heart rate, spontaneous baroreflex sensitivity, and c-Jun expression in the NTS. RESULTS Ethanol (1, 5, or 10 microg) microinjection into the RVLM elicited dose-dependent increases in RVLM NE and blood pressure in SHRs but not in WKY rats. Ethanol had no effect on the activity of the NE-containing neurons in the NTS of either strain. However, baroreflex dysfunction elicited by intra-NTS ethanol in conscious WKY rats was associated with enhanced expression of c-Jun in the NTS. CONCLUSIONS (1) Ethanol activation of the NE-containing neurons in the RVLM of SHRs contributes to the centrally mediated pressor response, (2) the NE-containing neurons in the NTS are not involved in ethanol-induced baroreflex dysfunction, and (3) direct activation of the c-Jun-containing neurons in the NTS is implicated in baroreflex dysfunction elicited by ethanol in normotensive rats.
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Affiliation(s)
- Guichu Li
- Department of Pharmacology and Toxicology, Brody School of Medicine at East Carolina University, Greenville, North Carolina, 27858, USA
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Chen Y, Chen H, Morris M. Enhanced osmotic responsiveness in angiotensin AT1a receptor deficient mice: evidence for a role for AT1b receptors. Exp Physiol 2005; 90:739-46. [PMID: 15944203 DOI: 10.1113/expphysiol.2005.030643] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Experiments were performed to study the role of angiotensin (Ang) AT1a and AT1b receptor subtypes in osmotic regulation of blood pressure using gene deletion and pharmacological methods. The cardiovascular effects of hypertonic saline (HS) or vasopressin (VP) delivered via vascular catheters were measured in Ang AT1a gene deletion (AT1a-/-) and control (AT1a+/+) mice. Blood pressure (BP) and heart rate (HR) were recorded in conscious mice using direct carotid catheters. Plasma osmolality and VP concentration were also measured. The major finding was that deletion of AT1a receptors resulted in enhanced BP response to osmotic stimulation. This was seen after acute HS injection (20 microl, 20% NaCl). The peak percentage change in mean arterial pressure (MAP) was 15.4+/-1.9% versus 28.1+/-2.4% (AT1a+/+versus AT1a-/-, respectively). Losartan (AT1 antagonist), but not PD123319 (AT2 antagonist), inhibited the HS-induced MAP response, specifically in AT1a-/- mice. Plasma osmolality and VP concentration were elevated after HS injection with no differences noted between groups. Vascular injection of VP (5 ng g-1) increased BP and HR, with similar MAP response between groups. Evidence shows that removal of Ang AT1a receptors results in a significant enhancement in the pressor response to acute osmotic stimulation. Studies of AT1 receptor blockade indicate that complementary Ang AT1b receptors, but not AT2 receptors, may be involved in the osmotic response.
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Affiliation(s)
- Yanfang Chen
- Department of Pharmacology and Taxicology, 3640 Colonel Glenn Highway, Wright State University School of Medicine, Dayton, OH 45435-0001, USA.
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Voigt JP, Hörtnagl H, Rex A, van Hove L, Bader M, Fink H. Brain angiotensin and anxiety-related behavior: The transgenic rat TGR(ASrAOGEN)680. Brain Res 2005; 1046:145-56. [PMID: 15869747 DOI: 10.1016/j.brainres.2005.03.048] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 03/24/2005] [Accepted: 03/29/2005] [Indexed: 11/21/2022]
Abstract
The transgenic rat TGR(ASrAOGEN)680, characterized by a transgene-producing antisense RNA against angiotensinogen in the brain, provides an opportunity to study the behavioral effects of angiotensin. While exposed to the elevated plus-maze (EPM) and the light/dark box, TGR(ASrAOGEN)680 rats showed more signs of anxiety compared to parental Sprague-Dawley (SD) rats. In the EPM, they made fewer entries into the open arms, spent less time there and more time on the closed arms. Head dips were reduced and U-turns were increased. In the light/dark box, the latency to the first re-entry into the light compartment was higher in TGR(ASrAOGEN)680. They displayed more SAP out from the dark and a reduced number of transitions between the two compartments. In the social interaction test, active social contacts were reduced, further suggesting an anxious phenotype. Although there was no transgenic effect on distance traveled in the open field, the more anxious TGR(ASrAOGEN)680 spent less time in the inner zone. Self-grooming was increased in TGR(ASrAOGEN)680 during exposure to the EPM and the open field, but was decreased in the social interaction test. In TGR(ASrAOGEN)680, tissue content of 5-HT and its metabolite 5-HIAA was lower in the hippocampus, frontal, and parietal cortex. HIAA and 5-HIAA/5-HT ratios were reduced in the hypothalamus, striatum, and septum. In the open field, the anxiogenic effect of the 5-HT2C/1B receptor agonist mCPP (0.5-1 mg/kg IP) was more pronounced in TGR(ASrAOGEN)680. The data suggest an anxious phenotype in rats with low brain angiotensinogen, possibly related to secondary dysfunctions of the brain serotonergic system.
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Affiliation(s)
- Jörg-Peter Voigt
- Institute of Pharmacology and Toxicology, School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
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Baltatu O, Campos LA, Bader M. Genetic targeting of the brain renin-angiotensin system in transgenic rats: Impact on stress-induced renin release. ACTA ACUST UNITED AC 2004; 181:579-84. [PMID: 15283773 DOI: 10.1111/j.1365-201x.2004.01333.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The advance of genetic technologies to permit tissue-specific targeted gene manipulation allowed the development of transgenic models with alterations of the renin-angiotensin (RAS) solely in the brain. We have used such methodology to develop a transgenic rat with a brain specific alteration of the RAS [TGR(ASrAOGEN)], in order to elucidate a causative role for the brain RAS and its relevance in different pathophysiological processes. The TGR(ASrAOGEN) rats have decreased levels of angiotensinogen (AOGEN) throughout the brain because of an antisense inhibition of the astroglial AOGEN synthesis. In this review we aimed at summarizing the experience obtained from utilizing the TGR(ASrAOGEN) rat model to study the brain RAS and present novel results providing evidence for the involvement of this system in stress-induced renin release.
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Affiliation(s)
- O Baltatu
- Max-Delbrück-Center for Molecular Medicine, Berlin-Buch, Germany
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