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Ziaja M, Urbanek KA, Kowalska K, Piastowska-Ciesielska AW. Angiotensin II and Angiotensin Receptors 1 and 2-Multifunctional System in Cells Biology, What Do We Know? Cells 2021; 10:cells10020381. [PMID: 33673178 PMCID: PMC7917773 DOI: 10.3390/cells10020381] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/05/2021] [Accepted: 02/09/2021] [Indexed: 12/13/2022] Open
Abstract
For years, the renin-angiotensin system (RAS) has been perceived as a system whose role is to primarily modulate the functioning of the cardiovascular system. Years of research into the role of RAS have provided the necessary data to confirm that the role of RAS is very complex and not limited to the cardiovascular system. The presence of individual elements of the renin-angiotensin (RA) system allows to control many processes, ranging from the memorization to pro-cancer processes. Maintaining the proportions between the individual axes of the RA system allows for achieving a balance, often called homeostasis. Thus, any disturbance in the expression or activity of individual RAS elements leads to pathophysiological processes.
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Royea J, Lacalle-Aurioles M, Trigiani LJ, Fermigier A, Hamel E. AT2R's (Angiotensin II Type 2 Receptor's) Role in Cognitive and Cerebrovascular Deficits in a Mouse Model of Alzheimer Disease. Hypertension 2020; 75:1464-1474. [PMID: 32362228 DOI: 10.1161/hypertensionaha.119.14431] [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] [Indexed: 11/16/2022]
Abstract
Antihypertensive medications targeting the renin-angiotensin system have lowered the incidence and progression of Alzheimer disease. Understanding how these medications function could lead to novel therapeutic strategies. AT4Rs (angiotensin IV receptors) have been associated with angiotensin receptor blockers' cognitive, cerebrovascular, and neuroinflammatory rescue in Alzheimer disease models. Yet, whether AT4Rs act alone or with AT2Rs remains unknown. Here, we investigated whether AT2Rs contribute to losartan's benefits and whether chronic AT2R activation could mimic angiotensin receptor blocker benefits in transgenic mice overexpressing familial Alzheimer disease mutations of the human APP (amyloid precursor protein). Losartan-treated mice (10 mg/kg per day, drinking water, 7 months) received intracerebroventricular (1 month) administration of vehicle or AT2R antagonist PD123319 (1.6 nmol/day). PD123319 countered losartan's benefits on spatial learning and memory, neurovascular coupling, and hampered those on oxidative stress and nitric oxide bioavailability. PD123319 did not oppose losartan's benefits on short-term memory and vasodilatory function and had no benefit on neuroinflammation or Aβ (amyloid β) pathology. Mice receiving either vehicle or selective AT2R agonist compound 21 (intracerebroventricular: 1 nmol/day, 1 month or drinking water: 10 mg/kg per day, 7 months), showed no improvement in memory, vasodilatory function, or nitric oxide bioavailability. Compound 21 treatment normalized neurovascular coupling, reduced astrogliosis independent of persisting microgliosis, and exacerbated oxidative stress in APP mice. Compound 21 reduced dense core Aβ plaques, but not diffuse plaques or Aβ species. Our findings suggest that targeting AT2Rs is not an ideal strategy for restoring Aβ-related cognitive and cerebrovascular deficits.
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Affiliation(s)
- Jessika Royea
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada H3A 2B4
| | - Maria Lacalle-Aurioles
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada H3A 2B4
| | - Lianne J Trigiani
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada H3A 2B4
| | - Alice Fermigier
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada H3A 2B4
| | - Edith Hamel
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada H3A 2B4
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Royea J, Martinot P, Hamel E. Memory and cerebrovascular deficits recovered following angiotensin IV intervention in a mouse model of Alzheimer's disease. Neurobiol Dis 2019; 134:104644. [PMID: 31669735 DOI: 10.1016/j.nbd.2019.104644] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 10/01/2019] [Accepted: 10/16/2019] [Indexed: 10/25/2022] Open
Abstract
Angiotensin II type 1 receptor antagonists like losartan have been found to lower the incidence and progression to Alzheimer's disease (AD), as well as rescue cognitive and cerebrovascular deficits in AD mouse models. We previously found that co-administration of an angiotensin IV (AngIV) receptor (AT4R) antagonist prevented losartan's benefits, identifying AT4Rs as a possible target to counter AD pathogenesis. Therein, we investigated whether directly targeting AT4Rs could counter AD pathogenesis in a well-characterized mouse model of AD. Wild-type and human amyloid precursor protein (APP) transgenic (J20 line) mice (4.5 months old) received vehicle or AngIV (~1.3 nmol/day, 1 month) intracerebroventricularly via osmotic minipumps. AngIV restored short-term memory, spatial learning and memory in APP mice. AngIV normalized hippocampal AT4R levels, increased hippocampal subgranular zone cellular proliferation and dendritic arborization, and reduced oxidative stress. AngIV rescued whisker-evoked neurovascular coupling, endothelial- and smooth muscle cell-mediated cerebral vasodilatory responses, and cerebrovascular nitric oxide bioavailability. AngIV did not alter blood pressure, neuroinflammation or amyloid-β (Aβ) pathology. These preclinical findings identify AT4R as a promising target to counter Aβ-related cognitive and cerebrovascular deficits in AD.
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Affiliation(s)
- Jessika Royea
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Pauline Martinot
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Edith Hamel
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada.
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Porcari CY, Araujo IG, Urzedo-Rodrigues L, De Luca LA, Menani JV, Caeiro XE, Imboden H, Antunes-Rodrigues J, Reis LC, Vivas L, Godino A, Mecawi AS. Whole body sodium depletion modifies AT1 mRNA expression and serotonin content in the dorsal raphe nucleus. J Neuroendocrinol 2019; 31:e12703. [PMID: 30803087 DOI: 10.1111/jne.12703] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 02/19/2019] [Accepted: 02/21/2019] [Indexed: 01/10/2023]
Abstract
Angiotensin II (Ang II) acts on Ang II type 1 (AT1) receptors located in the organum vasculosum and subfornical organ (SFO) of the lamina terminalis as a main facilitatory mechanism of sodium appetite. The brain serotonin (5-HT) system with soma located in the dorsal raphe nucleus (DRN) provides a main inhibitory mechanism. In the present study, we first investigated the existence of Ang II AT1 receptors in serotonergic DRN neurones. Then, we examined whether whole body sodium depletion affects the gene expression of the AT1a receptor subtype and the presumed functional significance of AT1 receptors. Using confocal microscopy, we found that tryptophan hydroxylase-2 and serotonin neurones express AT1 receptors in the DRN. Immunofluorescence quantification showed a significant reduction in 5-HT content but no change in AT1 receptor expression or AT1/5-HT colocalisation in the DRN after sodium depletion. Whole body sodium depletion also significantly increased Agtr1a mRNA expression in the SFO and DRN. Oral treatment with the AT1 receptor antagonist losartan reversed the changes in Agtr1a expression in the SFO but not the DRN. Losartan injection into either the DRN or the mesencephalic aqueduct had no influence on sodium depletion-induced 0.3 mol L-1 NaCl intake. The results indicate the expression of Agtr1a mRNA in the DRN and SFO as a marker of sodium depletion. They also suggest that serotonergic DRN neurones are targets for Ang II. However, the function of their AT1 receptors remains elusive.
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Affiliation(s)
- Cintia Yamila Porcari
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina
| | - Iracema Gomes Araujo
- Department of Physiological Sciences, Institute of Biological and Health Sciences, Federal Rural University of Rio de Janeiro, Seropedica, Brazil
| | - Lilia Urzedo-Rodrigues
- Department of Physiology and Pathology, School of Dentistry-FOAr, São Paulo State University, UNESP, Araraquara, Brazil
| | - Laurival Antonio De Luca
- Department of Physiology and Pathology, School of Dentistry-FOAr, São Paulo State University, UNESP, Araraquara, Brazil
| | - José Vanderlei Menani
- Department of Physiology and Pathology, School of Dentistry-FOAr, São Paulo State University, UNESP, Araraquara, Brazil
| | - Ximena Elizabeth Caeiro
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina
| | - Hans Imboden
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - José Antunes-Rodrigues
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil
| | - Luís Carlos Reis
- Department of Physiological Sciences, Institute of Biological and Health Sciences, Federal Rural University of Rio de Janeiro, Seropedica, Brazil
| | - Laura Vivas
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina
- Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Andrea Godino
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET-Universidad Nacional de Córdoba), Córdoba, Argentina
- Facultad de Psicología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - André Souza Mecawi
- Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
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Trigiani LJ, Royea J, Lacalle-Aurioles M, Tong XK, Hamel E. Pleiotropic Benefits of the Angiotensin Receptor Blocker Candesartan in a Mouse Model of Alzheimer Disease. Hypertension 2018; 72:1217-1226. [DOI: 10.1161/hypertensionaha.118.11775] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Lianne J. Trigiani
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, QC, Canada
| | - Jessika Royea
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, QC, Canada
| | - María Lacalle-Aurioles
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, QC, Canada
| | - Xin-Kang Tong
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, QC, Canada
| | - Edith Hamel
- From the Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, QC, Canada
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Ongali B, Nicolakakis N, Tong XK, Lecrux C, Imboden H, Hamel E. Transforming growth factor-β1 induces cerebrovascular dysfunction and astrogliosis through angiotensin II type 1 receptor-mediated signaling pathways. Can J Physiol Pharmacol 2018; 96:527-534. [PMID: 29505736 DOI: 10.1139/cjpp-2017-0640] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Transgenic mice constitutively overexpressing the cytokine transforming growth factor-β1 (TGF-β1) (TGF mice) display cerebrovascular alterations as seen in Alzheimer's disease (AD) and vascular cognitive impairment and dementia (VCID), but no or only subtle cognitive deficits. TGF-β1 may exert part of its deleterious effects through interactions with angiotensin II (AngII) type 1 receptor (AT1R) signaling pathways. We test such interactions in the brain and cerebral vessels of TGF mice by measuring cerebrovascular reactivity, levels of protein markers of vascular fibrosis, nitric oxide synthase activity, astrogliosis, and mnemonic performance in mice treated (6 months) with the AT1R blocker losartan (10 mg/kg per day) or the angiotensin converting enzyme inhibitor enalapril (3 mg/kg per day). Both treatments restored the severely impaired cerebrovascular reactivity to acetylcholine, calcitonin gene-related peptide, endothelin-1, and the baseline availability of nitric oxide in aged TGF mice. Losartan, but not enalapril, significantly reduced astrogliosis and cerebrovascular levels of profibrotic protein connective tissue growth factor while raising levels of antifibrotic enzyme matrix metallopeptidase-9. Memory was unaffected by aging and treatments. The results suggest a pivotal role for AngII in TGF-β1-induced cerebrovascular dysfunction and neuroinflammation through AT1R-mediated mechanisms. Further, they suggest that AngII blockers could be appropriate against vasculopathies and astrogliosis associated with AD and VCID.
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Affiliation(s)
- Brice Ongali
- a Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Nektaria Nicolakakis
- a Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Xin-Kang Tong
- a Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Clotilde Lecrux
- a Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Hans Imboden
- b Institute of Cell Biology, University of Bern Baltzerstrasse 43012 Bern, Switzerland
| | - Edith Hamel
- a Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
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Bohlender JM, Nussberger J, Tevaearai H, Imboden H. Angiotensinergic Innervation of the Human Right Atrium: Implications for Cardiac Reflexes. Am J Hypertens 2018; 31:188-196. [PMID: 28985343 PMCID: PMC5861579 DOI: 10.1093/ajh/hpx163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Accepted: 09/03/2017] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The right atrium is densely innervated and provides sensory input to important cardiocirculatory reflexes controlling cardiac output and blood pressure. Its angiotensin (Ang) II-expressing innervation may release Ang II as a neuropeptide cotransmitter to modulate reflexes but has not yet been characterized. METHODS Intraoperative surgical biopsies from human right atria (n = 7) were immunocytologically stained for Ang II, tyrosine hydroxylase (TH), and synaptophysin (SYN). Tissue angiotensins were extracted and quantified by radioimmunoassay. RESULTS Angiotensinergic fibers were frequent in epicardial nerves and around vessels with variable TH co-localization (none to >50%/bundle). Fibers were also widely distributed between cardiomyocytes and in the endocardium where they were typically nonvaricose, TH/SYN-negative and usually accompanied by varicose catecholaminergic fibers. In the endocardium, some showed large varicosities and were partially TH or SYN-positive. A few endocardial regions showed scattered nonvaricose Ang fibers ending directly between endothelial cells. Occasional clusters of thin varicose terminals co-localizing SYN or TH were located underneath, or protruded into, the endothelium. Endocardial density of Ang and TH-positive fibers was 30-300 vs. 200-450/mm2. Atrial Ang II, III, and I concentrations were 67, 16, and 5 fmol/g (median) while Ang IV and V were mostly undetectable. CONCLUSIONS The human right atrium harbors an abundant angiotensinergic innervation and a novel potential source of atrial Ang II. Most peripheral fibers were noncatecholaminergic afferents or preterminal vagal efferents and a minority was presumably sympathetic. Neuronal Ang II release from these fibers may modulate cardiac and circulatory reflexes independently from plasma and tissue Ang II sources.
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Affiliation(s)
- Jürgen M Bohlender
- Division of Clinical Pharmacology, Department of General Internal Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Institute of Pharmacology, University of Bern, Bern, Switzerland
| | - Jürg Nussberger
- Department of Medicine, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Hendrik Tevaearai
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Hans Imboden
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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Saavedra JM, Armando I. Angiotensin II AT2 Receptors Contribute to Regulate the Sympathoadrenal and Hormonal Reaction to Stress Stimuli. Cell Mol Neurobiol 2018; 38:85-108. [PMID: 28884431 PMCID: PMC6668356 DOI: 10.1007/s10571-017-0533-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 08/01/2017] [Indexed: 12/14/2022]
Abstract
Angiotensin II, through AT1 receptor stimulation, mediates multiple cardiovascular, metabolic, and behavioral functions including the response to stressors. Conversely, the function of Angiotensin II AT2 receptors has not been totally clarified. In adult rodents, AT2 receptor distribution is very limited but it is particularly high in the adrenal medulla. Recent results strongly indicate that AT2 receptors contribute to the regulation of the response to stress stimuli. This occurs in association with AT1 receptors, both receptor types reciprocally influencing their expression and therefore their function. AT2 receptors appear to influence the response to many types of stressors and in all components of the hypothalamic-pituitary-adrenal axis. The molecular mechanisms involved in AT2 receptor activation, the complex interactions with AT1 receptors, and additional factors participating in the control of AT2 receptor regulation and activity in response to stressors are only partially understood. Further research is necessary to close this knowledge gap and to clarify whether AT2 receptor activation may carry the potential of a major translational advance.
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Affiliation(s)
- J M Saavedra
- Department of Pharmacology and Physiology, Georgetown University Medical Center, 3900 Reservoir Road, Bldg. D, Room 287, Washington, DC, 20007, USA.
| | - I Armando
- The George Washington University School of Medicine and Health Sciences, Ross Hall Suite 738 2300 Eye Street, Washington, DC, USA
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Papadopoulos P, Tong XK, Imboden H, Hamel E. Losartan improves cerebrovascular function in a mouse model of Alzheimer's disease with combined overproduction of amyloid-β and transforming growth factor-β1. J Cereb Blood Flow Metab 2017; 37:1959-1970. [PMID: 27389178 PMCID: PMC5464692 DOI: 10.1177/0271678x16658489] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Alterations of the renin-angiotensin system have been implicated in the pathogenesis of Alzheimer's disease. We tested the efficacy of losartan (10 mg/kg/day for three months), a selective angiotensin II type 1 receptor antagonist, in alleviating cerebrovascular and cognitive deficits in double-transgenic mice (six months at endpoint) that overexpress a mutated form of the human amyloid precursor protein (APPSwe,Ind) and a constitutively active form of the transforming growth factor-β1, thereafter named A/T mice. Losartan rescued cerebrovascular reactivity, particularly the dilatory responses, but failed to attenuate astroglial activation and to normalize the neurovascular uncoupling response to sensory stimulation. The cognitive deficits of A/T mice were not restored by losartan nor were the increased brain levels of soluble and insoluble Aβ1-40 and Aβ1-42 peptides normalized. Our results are the first to demonstrate the capacity of losartan to improve cerebrovascular reactivity in an Alzheimer's disease mouse model of combined Aβ-induced vascular oxidative stress and transforming growth factor-β1-mediated vascular fibrosis. These data suggest that losartan may be promising for restoring cerebrovascular function in patients with vascular diseases at risk for vascular dementia or Alzheimer's disease. However, a combined therapy may be warranted for rescuing both vascular and cognitive deficits in a multifaceted pathology like Alzheimer's disease.
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Affiliation(s)
- Panayiota Papadopoulos
- 1 Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, Québec, Canada
| | - Xin-Kang Tong
- 1 Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, Québec, Canada
| | - Hans Imboden
- 2 Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Edith Hamel
- 1 Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, Québec, Canada
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Angiotensin IV Receptors Mediate the Cognitive and Cerebrovascular Benefits of Losartan in a Mouse Model of Alzheimer's Disease. J Neurosci 2017; 37:5562-5573. [PMID: 28476949 DOI: 10.1523/jneurosci.0329-17.2017] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 03/30/2017] [Accepted: 04/22/2017] [Indexed: 12/21/2022] Open
Abstract
The use of angiotensin receptor blockers (ARBs) correlates with reduced onset and progression of Alzheimer's disease (AD). The mechanism depicting how ARBs such as losartan restore cerebrovascular and cognitive deficits in AD is unknown. Here, we propose a mechanism underlying losartan's benefits by selectively blocking the effects of angiotensin IV (AngIV) at its receptor (AT4R) with divalinal in mice overexpressing the AD-related Swedish and Indiana mutations of the human amyloid precursor protein (APP mice) and WT mice. Young (3-month-old) mice were treated with losartan (∼10 mg/kg/d, 4 months), followed by intracerebroventricular administration of vehicle or divalinal in the final month of treatment. Spatial learning and memory were assessed using Morris water mazes at 3 and 4 months of losartan treatment. Cerebrovascular reactivity and whisker-evoked neurovascular coupling responses were measured at end point (∼7 months of age), together with biomarkers related to neuronal and vascular oxidative stress (superoxide dismutase-2), neuroinflammation (astroglial and microglial activation), neurogenesis (BrdU-labeled newborn cells), and amyloidosis [soluble amyloid-β (Aβ) species and Aβ plaque load]. Divalinal countered losartan's capacity to rescue spatial learning and memory and blocked losartan's benefits on dilatory function and baseline nitric oxide bioavailability. Divalinal reverted losartan's anti-inflammatory effects, but failed to modify losartan-mediated reductions in oxidative stress. Neither losartan nor divalinal affected arterial blood pressure or significantly altered the amyloid pathology in APP mice. Our findings identify activation of the AngIV/AT4R cascade as the underlying mechanism in losartan's benefits and a target that could restore Aβ-related cognitive and cerebrovascular deficits in AD.SIGNIFICANCE STATEMENT Antihypertensive medications that target the renin angiotensin system, such as angiotensin receptor blockers (ARBs), have been associated with lower incidence and progression of Alzheimer's disease (AD) in cohort studies. However, the manner by which ARBs mediate their beneficial effects is unknown. Here, the angiotensin IV receptor (AT4R) was identified as mediating the cognitive and cerebrovascular rescue of losartan, a commonly prescribed ARB, in a mouse model of AD. The AT4R was further implicated in mediating anti-inflammatory benefits. AT4R-mediated effects were independent from changes in blood pressure, amyloidosis, and oxidative stress. Overall, our results implicate the angiotensin IV/AT4R cascade as a promising candidate for AD intervention.
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Bohlender JM, Nussberger J, Birkhäuser F, Grouzmann E, Thalmann GN, Imboden H. Resetting of renal tissular renin-angiotensin and bradykinin-kallikrein systems after unilateral kidney denervation in rats. Histochem Cell Biol 2017; 147:585-593. [PMID: 28220244 DOI: 10.1007/s00418-017-1543-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2017] [Indexed: 01/11/2023]
Abstract
The renal tissular renin-angiotensin and bradykinin-kallikrein systems control kidney function together with the renal sympathetic innervation but their interaction is still unclear. To further elucidate this relationship, we investigated these systems in rats 6 days after left kidney denervation (DNX, n = 8) compared to sham-operated controls (CTR, n = 8). Plasma renin concentration was unchanged in DNX vs. CTR (p = NS). Kidney bradykinin (BK) and angiotensin (Ang) I and II concentrations decreased bilaterally in DNX vs. CTR rats (~20 to 40%, p < 0.05) together with Ang IV and V concentrations that were extremely low (p = NS). Renin, Ang III and dopamine concentrations decreased by ~25 to 50% and norepinephrine concentrations by 99% in DNX kidneys (p < 0.05) but were unaltered in opposite kidneys. Ang II/I and KA were comparable in DNX, contralateral and CTR kidneys. Ang III/II increased in right vs. DNX or CTR kidneys (40-50%, p < 0.05). Ang II was mainly located in tubular epithelium by immunocytological staining and its cellular distribution was unaffected by DNX. Moreover, the angiotensinergic and catecholaminergic innervation of right kidneys was unchanged vs. CTR. We found an important dependency of tissular Ang and BK levels on the renal innervation that may contribute to the resetting of kidney function after DNX. The DNX-induced peptide changes were not readily explained by kidney KA, renin or plasma Ang I generation. However, tissular peptide metabolism and compartmentalization may have played a central role. The mechanisms behind the concentration changes remain unclear and deserve further clarification.
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Affiliation(s)
- Jürgen M Bohlender
- Institute for Cell Biology, University of Bern, Bern, Switzerland. .,Department of Nephrology, Hypertension and Clinical Pharmacology, Inselspital, Bern University Hospital, University of Bern, Freiburgstr. 4, 3010, Bern, Switzerland.
| | - Jürg Nussberger
- Department of Medicine, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Frédéric Birkhäuser
- Department of Urology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Eric Grouzmann
- Service of Biomedicine, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - George N Thalmann
- Department of Urology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Hans Imboden
- Institute for Cell Biology, University of Bern, Bern, Switzerland
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12
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Ongali B, Nicolakakis N, Tong XK, Aboulkassim T, Imboden H, Hamel E. Enalapril Alone or Co-Administered with Losartan Rescues Cerebrovascular Dysfunction, but not Mnemonic Deficits or Amyloidosis in a Mouse Model of Alzheimer's Disease. J Alzheimers Dis 2016; 51:1183-95. [PMID: 26923013 DOI: 10.3233/jad-150868] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The co-administration of angiotensin converting enzyme inhibitors (ACEi) and angiotensin II (AngII) receptor blockers (ARB) that bind angiotensin type 1 receptors (AT1R) may protect from Alzheimer's disease (AD) better than each treatment taken alone. We tested the curative potential of the non brain-penetrant ACEi enalapril (3 mg/kg/day) administered for 3 months either alone or in combination with the brain penetrant ARB losartan (10 mg/kg/day) in aged (∼15 months) transgenic mice overexpressing a mutated form of the human amyloid-β protein precursor (AβPP, thereafter APP mice). We studied cerebrovascular function, protein levels of oxidative stress markers (superoxide dismutases SOD1, SOD2 and the NADPH oxidase subunit p67phox), amyloid-β (Aβ) pathology, astrogliosis, cholinergic innervation, AT1R and angiotensin IV receptor (AT4R) levels, together with cognitive performance. Both treatments normalized cerebrovascular reactivity and p67phox protein levels, but they did not reduce the cerebrovascular levels of SOD1. Combined treatment normalized cerebrovascular SOD2 levels, significantly attenuated astrogliosis, but did not reduce the increased levels of cerebrovascular AT1R. Yet, combined therapy enhanced thioflavin-S labeled Aβ plaque burden, a tendency not significant when Aβ1 - 42 plaque load was considered. None of the treatments rescued cognitive deficits, cortical AT4R or cholinergic innervation. We conclude that both treatments normalized cerebrovascular function by inhibiting the AngII-induced oxidative stress cascade, and that the positive effects of the combined therapy on astrogliosis were likely due to the ability of losartan to enter brain parenchyma. However, enalapril did not potentiate, and may even dampen, the reported cognitive benefits of losartan, raising caution when selecting the most appropriate antihypertensive therapy in AD patients.
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Affiliation(s)
- Brice Ongali
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada
| | - Nektaria Nicolakakis
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada
| | - Xing-Kang Tong
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada
| | - Tahar Aboulkassim
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada
| | - Hans Imboden
- Institute of Cell Biology, University of Bern, Switzerland
| | - Edith Hamel
- Laboratory of Cerebrovascular Research, Montreal Neurological Institute, McGill University, Montréal, QC, Canada
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Expression and localization of the diacylglycerol kinase family and of phosphoinositide signaling molecules in adrenal gland. Cell Tissue Res 2015; 362:295-305. [PMID: 26003177 DOI: 10.1007/s00441-015-2199-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 04/13/2015] [Indexed: 10/23/2022]
Abstract
Adrenal glands play a central role in the secretion of steroid hormones and catecholamines. Previous studies have revealed that molecules engaged in phosphoinositide (PI) turnover are expressed in the adrenal gland, suggesting the importance of PI signaling in adrenal signal transduction. Diacylglycerol kinase (DGK) catalyzes the phosphorylation of diacylglycerol (DG), a major second messenger in the PI signaling cascade. The DGK family is expressed in distinct patterns in endocrine organs at the mRNA and protein levels. Nevertheless, little is known about the characteristics and morphological aspects of DGKs in the adrenal gland. We have performed immunohistochemical analyses to investigate the expression and localization of DGK isozymes, together with PI signaling molecules, in the adrenal gland at the protein level. Our results show that the DGK family and a set of PI signaling molecules are expressed intensely in zona glomerulosa cells and medullary chromaffin cells in the adrenal gland. In adrenal cells, DGKγ localizes to the Golgi complex, DGKε to the plasma membrane, and DGKζ to the nucleus. These findings show the distinct expression and subcellular localization of DGK isozymes and PI signaling molecules in the adrenal gland, suggesting that each DGK isozyme has a role in signal transduction in adrenal cells, especially in the zona glomerulosa and medulla.
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Abstract
The purpose of this article is to review fundamentals in adrenal gland histophysiology. Key findings regarding the important signaling pathways involved in the regulation of steroidogenesis and adrenal growth are summarized. We illustrate how adrenal gland morphology and function are deeply interconnected in which novel signaling pathways (Wnt, Sonic hedgehog, Notch, β-catenin) or ionic channels are required for their integrity. Emphasis is given to exploring the mechanisms and challenges underlying the regulation of proliferation, growth, and functionality. Also addressed is the fact that while it is now well-accepted that steroidogenesis results from an enzymatic shuttle between mitochondria and endoplasmic reticulum, key questions still remain on the various aspects related to cellular uptake and delivery of free cholesterol. The significant progress achieved over the past decade regarding the precise molecular mechanisms by which the two main regulators of adrenal cortex, adrenocorticotropin hormone (ACTH) and angiotensin II act on their receptors is reviewed, including structure-activity relationships and their potential applications. Particular attention has been given to crucial second messengers and how various kinases, phosphatases, and cytoskeleton-associated proteins interact to ensure homeostasis and/or meet physiological demands. References to animal studies are also made in an attempt to unravel associated clinical conditions. Many of the aspects addressed in this article still represent a challenge for future studies, their outcome aimed at providing evidence that the adrenal gland, through its steroid hormones, occupies a central position in many situations where homeostasis is disrupted, thus highlighting the relevance of exploring and understanding how this key organ is regulated. © 2014 American Physiological Society. Compr Physiol 4:889-964, 2014.
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Affiliation(s)
- Nicole Gallo-Payet
- Division of Endocrinology, Department of Medicine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, and Centre de Recherche Clinique Étienne-Le Bel of the Centre Hospitalier Universitaire de Sherbrooke (CHUS), Sherbrooke, Quebec, Canada
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Ripa P, Ornello R, Pistoia F, Carolei A, Sacco S. The renin-angiotensin system: a possible contributor to migraine pathogenesis and prophylaxis. Expert Rev Neurother 2014; 14:1043-55. [PMID: 25115162 DOI: 10.1586/14737175.2014.946408] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The presence of a tissue-based renin-angiotensin system, independent of the systemic one, has been identified in several organs including the brain. Experimental models have suggested the involvement of the renin-angiotensin system in neurogenic inflammation, susceptibility to oxidative stress, endothelial dysfunction, and neuromodulation of nociceptive transmission, thus potentially contributing to the pathogenesis of migraine. Genetic factors that increase susceptibility to migraine may include angiotensin-converting enzyme polymorphism, although available data are controversial. Clinical studies have suggested that angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may be effective in migraine prophylaxis. However, further research should clarify whether the postulated preventive effect is attributable to a pharmacological action over and above the antihypertensive effect and should test their tolerability in subjects with normal blood pressure values. In patients with contraindications or not responding to conventional prophylactic drugs and in patients with comorbid arterial hypertension, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may be used for migraine prophylaxis.
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Affiliation(s)
- Patrizia Ripa
- Department of Biotechnological and Applied Clinical Sciences, Division of Clinical Neurology, University of L'Aquila, via Vetoio, 67100 L'Aquila, Italy
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Paz MC, Marchese NA, Stroppa MM, Gerez de Burgos NM, Imboden H, Baiardi G, Cancela LM, Bregonzio C. Involvement of the brain renin-angiotensin system (RAS) in the neuroadaptive responses induced by amphetamine in a two-injection protocol. Behav Brain Res 2014; 272:314-23. [PMID: 25046593 DOI: 10.1016/j.bbr.2014.07.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 07/08/2014] [Accepted: 07/10/2014] [Indexed: 11/25/2022]
Abstract
A single or repeated exposure to psychostimulants induces long-lasting neuroadaptative changes. Different neurotransmitter systems are involved in these responses including the neuropeptide angiotensin II. Our study tested the hypothesis that the neuroadaptative changes induced by amphetamine produce alterations in brain RAS components that are involved in the expression of the locomotor sensitization to the psychostimulant drug. Wistar male rats, pretreated with amphetamine were used 7 or 21 days later to study AT1 receptors by immunohistochemistry and western blot and also angiotensinogen mRNA and protein in caudate putamen and nucleus accumbens. A second group of animals was used to explore the possible role of Ang II AT1 receptors in the expression of behavioral sensitization. In these animals treated in the same way, bearing intra-cerebral cannula, the locomotor activity was tested 21 days later, after an amphetamine challenge injection and the animals received an AT1 blocker, losartan, or saline 5min before the amphetamine challenge. An increase of AT1 receptor density induced by amphetamine was found in both studied areas and a decrease in angiotensinogen mRNA and protein only in CPu at 21 days after treatment; meanwhile, no changes were established in NAcc. Finally, the increased locomotor activity induced by amphetamine challenge was blunted by losartan administration in CPu. No differences were detected in the behavioral sensitization when the AT1 blocker was injected in NAcc. Our results support the hypothesis of a key role of brain RAS in the neuroadaptative changes induced by amphetamine.
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Affiliation(s)
- Maria Constanza Paz
- Instituto de Farmacología Experimental Córdoba (IFEC-CONICET), Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba (UNC), Argentina
| | - Natalia Andrea Marchese
- Instituto de Farmacología Experimental Córdoba (IFEC-CONICET), Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba (UNC), Argentina
| | - Maria Mercedes Stroppa
- Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, UNC, Argentina
| | | | - Hans Imboden
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Gustavo Baiardi
- Laboratorio de Neurofarmacología, Instituto de Investigaciones Biológicas y Tecnológicas (IIBYT- CONICET), Universidad Nacional de Córdoba. Facultad de Ciencias Quimicas, Universidad Católica de Córdoba
| | - Liliana Marina Cancela
- Instituto de Farmacología Experimental Córdoba (IFEC-CONICET), Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba (UNC), Argentina
| | - Claudia Bregonzio
- Instituto de Farmacología Experimental Córdoba (IFEC-CONICET), Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba (UNC), Argentina.
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Ongali B, Nicolakakis N, Tong XK, Aboulkassim T, Papadopoulos P, Rosa-Neto P, Lecrux C, Imboden H, Hamel E. Angiotensin II type 1 receptor blocker losartan prevents and rescues cerebrovascular, neuropathological and cognitive deficits in an Alzheimer's disease model. Neurobiol Dis 2014; 68:126-36. [PMID: 24807206 DOI: 10.1016/j.nbd.2014.04.018] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 04/17/2014] [Accepted: 04/27/2014] [Indexed: 11/18/2022] Open
Abstract
Angiotensin II (AngII) receptor blockers that bind selectively AngII type 1 (AT1) receptors may protect from Alzheimer's disease (AD). We studied the ability of the AT1 receptor antagonist losartan to cure or prevent AD hallmarks in aged (~18months at endpoint, 3months treatment) or adult (~12months at endpoint, 10months treatment) human amyloid precursor protein (APP) transgenic mice. We tested learning and memory with the Morris water maze, and evaluated neurometabolic and neurovascular coupling using [(18)F]fluoro-2-deoxy-D-glucose-PET and laser Doppler flowmetry responses to whisker stimulation. Cerebrovascular reactivity was assessed with on-line videomicroscopy. We measured protein levels of oxidative stress enzymes (superoxide dismutases SOD1, SOD2 and NADPH oxidase subunit p67phox), and quantified soluble and deposited amyloid-β (Aβ) peptide, glial fibrillary acidic protein (GFAP), AngII receptors AT1 and AT2, angiotensin IV receptor AT4, and cortical cholinergic innervation. In aged APP mice, losartan did not improve learning but it consolidated memory acquisition and recall, and rescued neurovascular and neurometabolic coupling and cerebrovascular dilatory capacity. Losartan normalized cerebrovascular p67phox and SOD2 protein levels and up-regulated those of SOD1. Losartan attenuated astrogliosis, normalized AT1 and AT4 receptor levels, but failed to rescue the cholinergic deficit and the Aβ pathology. Given preventively, losartan protected cognitive function, cerebrovascular reactivity, and AT4 receptor levels. Like in aged APP mice, these benefits occurred without a decrease in soluble Aβ species or plaque load. We conclude that losartan exerts potent preventive and restorative effects on AD hallmarks, possibly by mitigating AT1-initiated oxidative stress and normalizing memory-related AT4 receptors.
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Affiliation(s)
- Brice Ongali
- Laboratory of Cerebrovascular Research, McGill University, Montréal, QC H3A 2B4, Canada
| | - Nektaria Nicolakakis
- Laboratory of Cerebrovascular Research, McGill University, Montréal, QC H3A 2B4, Canada
| | - Xin-Kang Tong
- Laboratory of Cerebrovascular Research, McGill University, Montréal, QC H3A 2B4, Canada
| | - Tahar Aboulkassim
- Laboratory of Cerebrovascular Research, McGill University, Montréal, QC H3A 2B4, Canada
| | | | - Pedro Rosa-Neto
- Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada; Douglas Hospital Research Centre, McGill University, Montréal, QC H3A 2B4, Canada
| | - Clotilde Lecrux
- Laboratory of Cerebrovascular Research, McGill University, Montréal, QC H3A 2B4, Canada
| | - Hans Imboden
- Institute of Cell Biology, University of Bern, Switzerland
| | - Edith Hamel
- Laboratory of Cerebrovascular Research, McGill University, Montréal, QC H3A 2B4, Canada.
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18
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Immunohistochemical detection of angiotensin II receptors in mouse cerebellum and adrenal gland using "in vivo cryotechnique". Histochem Cell Biol 2013; 140:477-90. [PMID: 23515786 DOI: 10.1007/s00418-013-1084-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2013] [Indexed: 12/11/2022]
Abstract
Angiotensin II (AT) receptors, including AT receptor type 1 (AT1R) and type 2 (AT2R), are expressed in the rodent central nervous system, but their distributions and activation states are still unclear. In this study, we have performed immunohistochemical analyses of AT receptors in mouse cerebellum and adrenal gland using our "in vivo cryotechnique" (IVCT). We used antibodies against amino-terminal domains of AT receptors, which are considered to undergo conformational changes upon the binding of AT. Immunoreactivity of AT1R was detected in mouse cerebellum, and was highest in the outer tissue areas of molecular layers using IVCT. The AT1R immunostaining largely overlapped with glial fibrillary acidic protein (GFAP), a marker of Bergmann glia. Surprisingly, the AT1R immunoreactivity in the cerebellar cortex was remarkably reduced following 5 and 10 min of hypoxia or direct administration of an AT1R antagonist, losartan. By contrast, in the adrenal cortex, such AT1R immunoreactivity detected at the zona glomerulosa did not change even after 15 min of hypoxia. The correlation of localization with GFAP and also hypoxia-induced decrease of its immunoreactivity were similarly observed by immunostaining of AT2R in the cerebellar specimens. These findings demonstrated that IVCT is useful to reveal dynamically changing immunoreactivities usually affected by receptor-ligand binding as well as hypoxia, and also suggested that functional activities of AT receptors are time-dependently modulated under hypoxia in the central nervous system in comparison with the adrenal glands.
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19
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Immunohistochemical Localization of AT1a, AT1b, and AT2 Angiotensin II Receptor Subtypes in the Rat Adrenal, Pituitary, and Brain with a Perspective Commentary. Int J Hypertens 2013; 2013:175428. [PMID: 23573410 PMCID: PMC3614054 DOI: 10.1155/2013/175428] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 02/01/2013] [Accepted: 02/05/2013] [Indexed: 11/17/2022] Open
Abstract
Angiotensin II increases blood pressure and stimulates thirst and sodium appetite in the brain. It also stimulates secretion of aldosterone from the adrenal zona glomerulosa and epinephrine from the adrenal medulla. The rat has 3 subtypes of angiotensin II receptors: AT1a, AT1b, and AT2. mRNAs for all three subtypes occur in the adrenal and brain. To immunohistochemically differentiate these receptor subtypes, rabbits were immunized with C-terminal fragments of these subtypes to generate receptor subtype-specific antibodies. Immunofluorescence revealed AT1a and AT2 receptors in adrenal zona glomerulosa and medulla. AT1b immunofluorescence was present in the zona glomerulosa, but not the medulla. Ultrastructural immunogold labeling for the AT1a receptor in glomerulosa and medullary cells localized it to plasma membrane, endocytic vesicles, multivesicular bodies, and the nucleus. AT1b and AT2, but not AT1a, immunofluorescence was observed in the anterior pituitary. Stellate cells were AT1b positive while ovoid cells were AT2 positive. In the brain, neurons were AT1a, AT1b, and AT2 positive, but glia was only AT1b positive. Highest levels of AT1a, AT1b, and AT2 receptor immunofluorescence were in the subfornical organ, median eminence, area postrema, paraventricular nucleus, and solitary tract nucleus. These studies complement those employing different techniques to characterize Ang II receptors.
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Patil J, Stucki S, Nussberger J, Schaffner T, Gygax S, Bohlender J, Imboden H. Angiotensinergic and noradrenergic neurons in the rat and human heart. ACTA ACUST UNITED AC 2011; 167:31-41. [DOI: 10.1016/j.regpep.2010.11.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 10/28/2010] [Accepted: 11/25/2010] [Indexed: 11/29/2022]
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21
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Frenkel L, Dimant B, Portiansky EL, Imboden H, Maldonado H, Delorenzi A. Neuroanatomical distribution of angiotensin-II-like neuropeptide within the central nervous system of the crab Chasmagnathus; physiological changes triggered by water deprivation. Cell Tissue Res 2010; 341:181-95. [DOI: 10.1007/s00441-010-0990-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Accepted: 05/03/2010] [Indexed: 10/19/2022]
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Patil J, Schwab A, Nussberger J, Schaffner T, Saavedra JM, Imboden H. Intraneuronal angiotensinergic system in rat and human dorsal root ganglia. ACTA ACUST UNITED AC 2010; 162:90-8. [PMID: 20346377 DOI: 10.1016/j.regpep.2010.03.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 01/29/2010] [Accepted: 03/16/2010] [Indexed: 11/30/2022]
Abstract
To elucidate the local formation of angiotensin II (Ang II) in the neurons of sensory dorsal root ganglia (DRG), we studied the expression of angiotensinogen (Ang-N)-, renin-, angiotensin converting enzyme (ACE)- and cathepsin D-mRNA, and the presence of protein renin, Ang II, Substance P and calcitonin gene-related peptide (CGRP) in the rat and human thoracic DRG. Quantitative real time PCR (qRT-PCR) studies revealed that rat DRG expressed substantial amounts of Ang-N- and ACE mRNA, while renin mRNA as well as the protein renin were untraceable. Cathepsin D-mRNA and cathepsin D-protein were detected in the rat DRG indicating the possibility of existence of pathways alternative to renin for Ang I formation. Angiotensin peptides were successfully detected with high performance liquid chromatography and radioimmunoassay in human DRG extracts. In situ hybridization in rat DRG confirmed additionally expression of Ang-N mRNA in the cytoplasm of numerous neurons. Intracellular Ang II staining could be shown in number of neurons and their processes in both the rat and human DRG. Interestingly we observed neuronal processes with angiotensinergic synapses en passant, colocalized with synaptophysin, within the DRG. In the DRG, we also identified by qRT-PCR, expression of Ang II receptor AT(1A) and AT(2)-mRNA while AT(1B)-mRNA was not traceable. In some neurons Substance P and CGRP were found colocalized with Ang II. The intracellular localization and colocalization of Ang II with Substance P and CGRP in the DRG neurons may indicate a participation and function of Ang II in the regulation of nociception. In conclusion, these results suggest that Ang II may be produced locally in the neurons of rat and human DRG and act as a neurotransmitter.
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Affiliation(s)
- Jaspal Patil
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland
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23
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Harada K, Matsuoka H, Fujimoto N, Endo Y, Hasegawa Y, Matsuo A, Kikuchi Y, Matsumoto T, Inoue M. Localization of type-2 angiotensin II receptor in adrenal gland. J Histochem Cytochem 2010; 58:585-93. [PMID: 20231739 DOI: 10.1369/jhc.2010.955575] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The localization of the type-2 angiotensin II receptor (AT2) in the adrenal glands of rats, guinea pigs, bovines, and humans was examined at the mRNA and protein levels. PCR products for AT2 were detected in the adrenal cortices and adrenal medullae of all the mammals examined with an RT-PCR technique. Three different anti-AT2 antibodies (Abs), whose specificity was confirmed in our hands, recognized a 50-kDa protein in the adrenal glands of the four mammals, and this recognition was abolished by the preabsorption of an Ab with an antigen. Immunoblotting and immunohistochemistry revealed that the 50-kDa protein was expressed consistently and variably in the adrenal cortices and medullae of various mammals, respectively. We conclude that the 50-kDa AT2 is consistently expressed in the adrenal cortex in a wide variety of mammals.
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Affiliation(s)
- Keita Harada
- Department of Cell and Systems Physiology, University of Occupational and Environmental Health, Kitakyushu, Japan
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Imboden H, Patil J, Nussberger J, Nicoud F, Hess B, Ahmed N, Schaffner T, Wellner M, Müller D, Inagami T, Senbonmatsu T, Pavel J, Saavedra JM. Endogenous angiotensinergic system in neurons of rat and human trigeminal ganglia. ACTA ACUST UNITED AC 2009; 154:23-31. [PMID: 19323983 DOI: 10.1016/j.regpep.2009.02.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 01/13/2009] [Accepted: 02/03/2009] [Indexed: 12/21/2022]
Abstract
To clarify the role of Angiotensin II (Ang II) in the sensory system and especially in the trigeminal ganglia, we studied the expression of angiotensinogen (Ang-N)-, renin-, angiotensin converting enzyme (ACE)- and cathepsin D-mRNA, and the presence of Ang II and substance P in the rat and human trigeminal ganglia. The rat trigeminal ganglia expressed substantial amounts of Ang-N- and ACE mRNA as determined by quantitative real time PCR. Renin mRNA was untraceable in rat samples. Cathepsin D was detected in the rat trigeminal ganglia indicating the possibility of existence of pathways alternative to renin for Ang I formation. In situ hybridization in rat trigeminal ganglia revealed expression of Ang-N mRNA in the cytoplasm of numerous neurons. By using immunocytochemistry, a number of neurons and their processes in both the rat and human trigeminal ganglia were stained for Ang II. Post in situ hybridization immunocytochemistry reveals that in the rat trigeminal ganglia some, but not all Ang-N mRNA-positive neurons marked for Ang II. In some neurons Substance P was found colocalized with Ang II. Angiotensins from rat trigeminal ganglia were quantitated by radioimmunoassay with and without prior separation by high performance liquid chromatography. Immunoreactive angiotensin II (ir-Ang II) was consistently present and the sum of true Ang II (1-8) octapeptide and its specifically measured metabolites were found to account for it. Radioimmunological and immunocytochemical evidence of ir-Ang II in neuronal tissue is compatible with Ang II as a neurotransmitter. In conclusion, these results suggest that Ang II could be produced locally in the neurons of rat trigeminal ganglia. The localization and colocalization of neuronal Ang II with Substance P in the trigeminal ganglia neurons may be the basis for a participation and function of Ang II in the regulation of nociception and migraine pathology.
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Affiliation(s)
- Hans Imboden
- Institute of Cell Biology, University of Bern, Bern, Switzerland.
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Patil J, Heiniger E, Schaffner T, Mühlemann O, Imboden H. Angiotensinergic neurons in sympathetic coeliac ganglia innervating rat and human mesenteric resistance blood vessels. ACTA ACUST UNITED AC 2008; 147:82-7. [PMID: 18308407 DOI: 10.1016/j.regpep.2008.01.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Revised: 01/08/2008] [Accepted: 01/11/2008] [Indexed: 10/22/2022]
Abstract
In contrast to the current belief that angiotensin II (Ang II) interacts with the sympathetic nervous system only as a circulating hormone, we document here the existence of endogenous Ang II in the neurons of rat and human sympathetic coeliac ganglia and their angiotensinergic innervation with mesenteric resistance blood vessels. Angiotensinogen - and angiotensin converting enzyme-mRNA were detected by using quantitative real time polymerase chain reaction in total RNA extracts of rat coeliac ganglia, while renin mRNA was untraceable. Cathepsin D, a protease responsible for cleavage beneath other substrates also angiotensinogen to angiotensin I, was successfully detected in rat coeliac ganglia indicating the possibility of existence of alternative pathways. Angiotensinogen mRNA was also detected by in situ hybridization in the cytoplasm of neurons of rat coeliac ganglia. Immunoreactivity for Ang II was demonstrated in rat and human coeliac ganglia as well as with mesenteric resistance blood vessels. By using confocal laser scanning microscopy we were able to demonstrate the presence of angiotensinergic synapses en passant along side of vascular smooth muscle cells. Our findings indicate that Ang II is synthesized inside the neurons of sympathetic coeliac ganglia and may act as an endogenous neurotransmitter locally with the mesenteric resistance blood vessels.
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Affiliation(s)
- Jaspal Patil
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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Roberge C, Carpentier AC, Langlois MF, Baillargeon JP, Ardilouze JL, Maheux P, Gallo-Payet N. Adrenocortical dysregulation as a major player in insulin resistance and onset of obesity. Am J Physiol Endocrinol Metab 2007; 293:E1465-78. [PMID: 17911338 DOI: 10.1152/ajpendo.00516.2007] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The aim of this review is to explore the dysregulation of adrenocortical secretions as a major contributor in the development of obesity and insulin resistance. Disturbance of adipose tissue physiology is one of the primary events in the development of pathologies associated with the metabolic syndrome, such as obesity and type 2 diabetes. Several studies indicate that alterations in metabolism of glucocorticoids (GC) and androgens, as well as aldosterone in excess, are involved in the emergence of metabolic syndrome. Cross talk among adipose tissue, the hypothalamo-pituitary complex, and adrenal gland activity plays a major role in the control of food intake, glucose metabolism, lipid storage, and energy balance. Perturbation of this cross talk induces alterations in the regulatory mechanisms of adrenocortical steroid synthesis, secretion, degradation, and/or recycling, at the level of the zonae glomerulosa (aldosterone), fasciculata (GC and GC metabolites), and reticularis (androgens and androgen precursors DHEA and DHEAS). As a whole, these adrenocortical perturbations contribute to the development of metabolic syndrome at both the paracrine and systemic level by favoring the physiological dysregulation of organs responsive to aldosterone, GC, and/or androgens, including adipose tissue.
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Affiliation(s)
- Claude Roberge
- Department of Medicine, Faculty of Medicine, Université de Sherbrooke, 3001, 12th Ave. North, Sherbrooke, QC, Canada J1H 5N4
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Woost PG, Kolb RJ, Finesilver M, Mackraj I, Imboden H, Coffman TM, Hopfer U. Strategy for the development of a matched set of transport-competent, angiotensin receptor-deficient proximal tubule cell lines. In Vitro Cell Dev Biol Anim 2006; 42:189-200. [PMID: 16948500 DOI: 10.1290/0511076.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In the proximal convoluted tubule (PCT) angiotensin II (Ang II) modulates fluid and electrolyte transport through at least two pharmacologically distinct receptor subtypes: AT(1) and AT(2). Development of cell lines that lack these receptors are potentially useful models to probe the complex cellular details of Ang II regulation. To this end, angiotensin receptor- deficient mice were bred with an Immortomouse(R), which harbors a thermolabile SV40 large-T antigen (Tag). S1 PCT segments from kidneys of F(2) mice were microdissected, placed in culture, and maintained under conditions that enhanced cell growth, i.e., promoted Tag expression and thermostability. Three different types of angiotensin receptor-deficient cell lines, (AT(1A) [-/-], Tag [+/-]), (AT(1B) [-/-], Tag [+/-]), and (AT(1A) [-/-], AT(1B) [-/-], Tag [+/+]), as well as wild type cell lines were generated. Screening and characterization, which were conducted under culture conditions that promoted cellular differentiation, included: measurements of transepithelial transport, such as basal monolayer short-circuit current (Isc; -3 to 3 microA/cm2), basal monolayer conductance (G, 2 to 10 mS/cm2), Na3(+)-phosphate cotransport (DeltaIsc of 2 to 3 microA/cm(2) at 1 mM), and Na(3)(+)-succinate cotransport (DeltaIsc of 1 to 9 microA/cm(2) at 2 mM). Morphology of cell monolayers showed an extensive brush border, well-defined tight junctions, and primary cilia. Receptor functionality was assessed by Ang II-stimulated beta-arrestin 2 translocation and showed an Ang II-mediated response in wild type but not (AT(1A) [-/ -], AT(1B) [-/-]) cells. Cell lines were amplified, yielding a virtually unlimited supply of highly differentiated, transport-competent, angiotensin receptor-deficient PCT cell lines.
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Affiliation(s)
- Philip G Woost
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106-4970, USA.
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Hoffmann A, Cool DR. Characterization of two polyclonal peptide antibodies that recognize the carboxy terminus of angiotensin II AT1A and AT1B receptors. Clin Exp Pharmacol Physiol 2006; 32:936-43. [PMID: 16405450 DOI: 10.1111/j.1440-1681.2005.04288.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. The differential identification of the angiotensin AT1A and AT1B receptor subtypes is impaired by the existing>96% homology of both receptors. In the present study, we characterized two polyclonal rabbit peptide antibodies, namely alpha-AT1A and alpha-AT1B, that recognize the C-terminal region of mouse AT1A and AT1B receptors, respectively. 2. In immunoblotting, both antibodies detected two major AT1 receptor-specific bands at sizes of 72.5 and 87.6 kDa in mouse tissues and in Neuro-2a cell lysates. In immunohistochemistry, antibodies demonstrated AT1 receptor-specific staining in renal proximal and distal tubules, as well as in kidney glomeruli. In addition, both antibodies stained AT1 receptors in Neuro-2a cells with G-protein receptor typical distribution. Dot-blot and ELISA analysis of the alpha-AT1A antibody showed 2.5- to fourfold higher selectivity for its AT1A receptor target peptide (1A-PEP) compared with the non-specific AT1B receptor peptide (1B-PEP). In contrast, the alpha-AT1B antibody showed high binding affinity towards its target peptide 1B-PEP, but also demonstrated high cross-reactivity for the non-specific peptide 1A-PEP (1.4- to twofold in ELISA and dot-blot analysis). In contrast with the lack of recognition by the alpha-AT1B antibody, the alpha-AT1A antibody selectively recognized the AT1A receptor fused to red fluorescence protein in transiently transfected Chinese hamster ovary cells. 3. In summary, we have generated two new peptide antibodies to the mouse AT1A and AT1B receptors (alpha-AT1A and alpha-AT1B), of which the alpha-AT1A antibody has the capability to distinguish AT1A receptor types in immunological approaches.
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Affiliation(s)
- Andrea Hoffmann
- Department of Pharmacology and Toxicology, Wright State University School of Medicine, Dayton, Ohio 45435, USA.
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Zhou J, Pavel J, Macova M, Yu ZX, Imboden H, Ge L, Nishioku T, Dou J, Delgiacco E, Saavedra JM. AT1 receptor blockade regulates the local angiotensin II system in cerebral microvessels from spontaneously hypertensive rats. Stroke 2006; 37:1271-6. [PMID: 16601219 DOI: 10.1161/01.str.0000217404.64352.d7] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Blockade of angiotensin II AT1 receptors in cerebral microvessels protects against brain ischemia and inflammation. In this study, we tried to clarify the presence and regulation of the local renin-angiotensin system (RAS) in brain microvessels in hypertension. METHODS Spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) controls were treated with an AT1 receptor antagonist (candesartan, 0.3 mg/kg per day) via subcutaneous osmotic minipumps for 4 weeks. The expression and localization of RAS components and the effect of AT1 receptor blockade were assessed by Affymetrix microarray, qRT-PCR, Western blots, immunohistochemistry and immunofluorescence. RESULTS We found transcripts of most of RAS components in our microarray database, and confirmed their expression by qRT-PCR. Angiotensinogen (Aogen), angiotensin-converting enzyme (ACE) and AT1 receptors were localized to the endothelium. There was no evidence of AT2 receptor localization in the microvascular endothelium. In SHR, (pro)renin receptor mRNA and AT1 receptor mRNA and protein expression were higher, whereas Aogen, ACE mRNA and AT2 receptor mRNA and protein expression were lower than in WKY rats. Candesartan treatment increased Aogen, ACE and AT2 receptor in SHR, and increased ACE and decreased Aogen in WKY rats, without affecting the (pro)renin and AT1 receptors. CONCLUSIONS Increased (pro)renin and AT1 receptor expression in SHR substantiates the importance of the local RAS overdrive in the cerebrovascular pathophysiology in hypertension. AT1 receptor blockade and increased AT2 receptor stimulation after administration of candesartan may contribute to the protection against brain ischemia and inflammation.
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Affiliation(s)
- Jin Zhou
- Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA.
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Fritz RD, Radziwill G. The scaffold protein CNK1 interacts with the angiotensin II type 2 receptor. Biochem Biophys Res Commun 2005; 338:1906-12. [PMID: 16289034 DOI: 10.1016/j.bbrc.2005.10.168] [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] [Received: 10/24/2005] [Accepted: 10/27/2005] [Indexed: 11/23/2022]
Abstract
The scaffold protein CNK1 mediates proliferative as well as antiproliferative responses including differentiation and apoptosis. The angiotensin II type 2 (AT2) receptor belongs to the class of G protein-coupled receptors and also promotes antiproliferative effects. Here we report that CNK1 binds through the sterile alpha motif (SAM) and the conserved region in CNK (CRIC) to the AT2 receptor. The exchange of a conserved leucine residue with arginine in the CRIC domain increases the binding affinity of CNK1 to the AT2 receptor. The insertion of a negatively charged amino acid stretch into the linker region between the N- and the C-terminal part of CNK1 strengthens the interaction between CNK1 and the AT2 receptor in a Ras-regulated manner. The biological significance of the interaction was supported by coprecipitation of CNK1 and the AT2 receptor in mouse heart extracts. Thus, CNK1 may play a role in the AT2 receptor-mediated signaling pathways.
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Affiliation(s)
- Rafael D Fritz
- Institute of Medical Virology, University of Zurich, 8006 Zurich, Switzerland
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Otis M, Campbell S, Payet MD, Gallo-Payet N. Angiotensin II stimulates protein synthesis and inhibits proliferation in primary cultures of rat adrenal glomerulosa cells. Endocrinology 2005; 146:633-42. [PMID: 15539557 DOI: 10.1210/en.2004-0935] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Angiotensin II (Ang II) is one of the most important stimuli of rat adrenal glomerulosa cells. The aim of the present study was to investigate whether Ang II can stimulate cell proliferation and/or hypertrophy and investigate pathways and intracellular targets. A 3-d treatment with Ang II (5-100 nm), through the Ang II type 1 receptor subtype, abolished cell proliferation observed in control cells but increased protein synthesis. Preincubation with PD98059 (a MAPK kinase inhibitor) abolished basal proliferation and had no effect on basal protein synthesis but did reverse the effect of Ang II on protein synthesis. The p38 MAPK inhibitor SB203580 reversed the inhibitory effect on cell proliferation and abolished the increase in protein synthesis, whereas the c-Jun N-terminal kinase inhibitor SP600125 had no effect. Time-course studies revealed that Ang II stimulated phosphorylation of both p42/p44mapk and p38 MAPK but did not activate c-Jun N-terminal kinase. Ang II had no effect on the level of cyclin E expression but increased the expression of the cyclin-dependent kinase, p27Kip1, an effect abolished in cells preincubated with SB203580 and PD98059. In conclusion, in cultured rat glomerulosa cells, a 3-d treatment with Ang II increases protein synthesis, with a concomitant decrease in proliferation. These effects are mediated by both the p42/p44mapk and p38 MAPK pathways, which increase expression of the steroidogenic enzymes, steroidogenic acute regulatory protein and 3beta-hydroxysteroid dehydrogenase and p27Kip1, a protein known to block the cell cycle in G1 phase. Together these results support the key role of Ang II as a stimulus of steroid synthesis rather than a proliferating factor.
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Affiliation(s)
- Mélissa Otis
- Service of Endocrinology, Faculty of Medicine, Université de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, Québec, Canada J1H 5N4
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Wong PF, Lee SST, Cheung WT. Immunohistochemical colocalization of type II angiotensin receptors with somatostatin in rat pancreas. ACTA ACUST UNITED AC 2004; 117:195-205. [PMID: 14749040 DOI: 10.1016/j.regpep.2003.10.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Earlier studies indicate that binding sites of type II angiotensin (AT2) receptors are detected all over the pancreas, as well as in the pancreatic exocrine cell line AR4-2J. However, lack of corresponding functional AT2 receptor responses can be detected in the exocrine pancreas. The aim of present study is to determine the protein expression of AT2 receptors in the pancreas by probing with an AT2 receptor-specific antibody, and to examine the role of AT2 receptors in the regulation of pancreatic endocrine hormone release. In Western protein analysis of adult rat tissues, expression of AT2 receptor-immunoreactive bands of 56, 68, and 78 kDa was detected in the adrenal, kidney, liver, salivary glands, and pancreas. In adult rat pancreas, strong immunoreactivity was detected on cells that were located at the outer region of Langerhans islets. Immunohistochemical studies indicated that AT2 receptors colocalized with somatostatin-producing cells in the endocrine pancreas. Consistent with the findings in adult pancreas, abundant expression of AT2 receptors was also detected in immortalized rat pancreatic endocrinal cells lines RIN-m and RIN-14B. To examine the role of AT2 receptors on somatostatin secretion in the pancreas, angiotensin-stimulated somatostatin release from pancreatic RIN-14B cells was studied by an enzyme immunoassay in the absence or presence of various subtype-selective angiotensin analogues. There was a basal release of somatostatin from RIN-14B cells at a rate of 8.72 +/- 4.21 ng/10(6) cells (n = 7). Angiotensin II (1 nM-10 microM) stimulated a biphasic somatostatin release in a dose-dependent manner with an apparent EC50 value of 49.3 +/- 25.9 nM (n = 5), and reached maximal release at 1 microM angiotensin II (982 +/- 147.34% over basal secretion; n = 5). Moreover, the AT2 receptor-selective angiotensin analogue, CGP42112, was 1000 times more potent than the AT1 receptor-selective angiotensin analogue, losartan, in inhibiting angiotensin II-stimulated somatostatin release. These results suggest that angiotensin may modulate pancreatic hormone release via regulation of somatostatin secretion.
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Affiliation(s)
- Pui-Fan Wong
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
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Spät A, Hunyady L. Control of aldosterone secretion: a model for convergence in cellular signaling pathways. Physiol Rev 2004; 84:489-539. [PMID: 15044681 DOI: 10.1152/physrev.00030.2003] [Citation(s) in RCA: 344] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Aldosterone secretion by glomerulosa cells is stimulated by angiotensin II (ANG II), extracellular K(+), corticotrophin, and several paracrine factors. Electrophysiological, fluorimetric, and molecular biological techniques have significantly clarified the molecular action of these stimuli. The steroidogenic effect of corticotrophin is mediated by adenylyl cyclase, whereas potassium activates voltage-operated Ca(2+) channels. ANG II, bound to AT(1) receptors, acts through the inositol 1,4,5-trisphosphate (IP(3))-Ca(2+)/calmodulin system. All three types of IP(3) receptors are coexpressed, rendering a complex control of Ca(2+) release possible. Ca(2+) release is followed by both capacitative and voltage-activated Ca(2+) influx. ANG II inhibits the background K(+) channel TASK and Na(+)-K(+)-ATPase, and the ensuing depolarization activates T-type (Ca(v)3.2) Ca(2+) channels. Activation of protein kinase C by diacylglycerol (DAG) inhibits aldosterone production, whereas the arachidonate released from DAG in ANG II-stimulated cells is converted by lipoxygenase to 12-hydroxyeicosatetraenoic acid, which may also induce Ca(2+) signaling. Feedback effects and cross-talk of signal-transducing pathways sensitize glomerulosa cells to low-intensity stimuli, such as physiological elevations of [K(+)] (< or =1 mM), ANG II, and ACTH. Ca(2+) signaling is also modified by cell swelling, as well as receptor desensitization, resensitization, and downregulation. Long-term regulation of glomerulosa cells involves cell growth and proliferation and induction of steroidogenic enzymes. Ca(2+), receptor, and nonreceptor tyrosine kinases and mitogen-activated kinases participate in these processes. Ca(2+)- and cAMP-dependent phosphorylation induce the transfer of the steroid precursor cholesterol from the cytoplasm to the inner mitochondrial membrane. Ca(2+) signaling, transferred into the mitochondria, stimulates the reduction of pyridine nucleotides.
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Affiliation(s)
- András Spät
- Dept. of Physiology, Semmelweis University, Faculty of Medicine, PO Box 259, H-1444 Budapest, Hungary.
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Senbonmatsu T, Saito T, Landon EJ, Watanabe O, Price E, Roberts RL, Imboden H, Fitzgerald TG, Gaffney FA, Inagami T. A novel angiotensin II type 2 receptor signaling pathway: possible role in cardiac hypertrophy. EMBO J 2004; 22:6471-82. [PMID: 14657020 PMCID: PMC291832 DOI: 10.1093/emboj/cdg637] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We describe a novel signaling mechanism mediated by the G-protein-coupled receptor (GPCR) angiotensin II (Ang II) type 2 receptor (AT(2)). Yeast two-hybrid studies and affinity column binding assay show that the isolated AT(2) C-terminus binds to the transcription factor promyelocytic zinc finger protein (PLZF). Cellular studies employing confocal microscopy show that Ang II stimulation induces cytosolic PLZF to co-localize with AT(2) at the plasma membrane, then drives AT(2) and PLZF to internalize. PLZF slowly emerges in the nucleus whereas AT(2) accumulates in the perinuclear region. Nuclear PLZF binds to a consensus sequence of the phosphatidylinositol-3 kinase p85 alpha subunit (p85 alpha PI3K) gene. AT(2) enhances expression of p85 alpha PI3K followed by enhanced p70(S6) kinase, essential to protein synthesis. An inactive mutant of PLZF abolishes this effect. PLZF is expressed robustly in the heart in contrast to many other tissues. This cardiac selective pathway involving AT(2), PLZF and p85 alpha PI3K may explain the absence of a cardiac hypertrophic response in AT(2) gene-deleted mice.
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Affiliation(s)
- Takaaki Senbonmatsu
- Departments of Biochemistry, Pharmacology, Pathology and Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
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Asashima T, Iizasa H, Terasaki T, Nakashima E. Rat brain pericyte cell lines expressing beta2-adrenergic receptor, angiotensin II receptor type 1A, klotho, and CXCR4 mRNAs despite having endothelial cell markers. J Cell Physiol 2003; 197:69-76. [PMID: 12942542 DOI: 10.1002/jcp.10343] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Pericytes are an integral component of blood capillaries, but their involvement in a variety of conditions and diseases, including hypertension and multiple sclerosis, is poorly understood. In order to analyze the mRNA expression of markers related to hypertension and multiple sclerosis in rat brain pericytes, we have established brain capillary pericyte cell lines from temperature-sensitive SV40 large T antigen transgenic rats. The newly established clones showed similar biochemical and morphological properties to primary pericytes. The expression of endothelial cell-related markers Flt-1, Flk-1, Tie-1, and Tie-2 was evaluated by RT-PCR analysis. beta2-Adrenergic receptor (beta2-AR), angiotensin II receptor type1A (AT1A), and klotho were also evaluated as markers related to hypertension and multiple sclerosis. All of the isolated clones expressed beta2-AR, AT1A and klotho genes. They also stably expressed Flt-1 and Tie-2, while Flk-1, Tie-1 and CXCR4 were expressed only at low levels in some of the clones. The expressions of AT1 in TR-PCT1 were determined by Western blotting. Angiotensin II stimulated migration of pericytes. This effect was blocked by an AT1 antagonist. The pericyte cell lines established here are pluripotent, and should be useful for analysis of the reactivity and biological roles of pericytes.
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Affiliation(s)
- Tomoko Asashima
- Department of Pharmaceutics, Kyoritsu College of Pharmacy, Tokyo, Japan
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Ahmad Z, Milligan CJ, Paton JFR, Deuchars J. Angiotensin type 1 receptor immunoreactivity in the thoracic spinal cord. Brain Res 2003; 985:21-31. [PMID: 12957365 DOI: 10.1016/s0006-8993(03)03112-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The angiotensin II type 1 receptor (AT1R) in the central nervous system (CNS) plays a pivotal role in determining blood pressure. However, the relationship of the receptor to neurones in the spinal cord which are the final CNS contribution to sympathetic outflow is unknown. Here we first use RT-PCR to show that AT1A, AT1B and AT2 receptors are expressed in thoracic spinal cord of the rat. Using light microscopic immunohistochemistry we find that the AT1 receptor in the thoracic spinal cord is located on neurones and ependymal cells. Neurones with extensive immunostaining of somata and dendrites were located in the intermediolateral cell column (IML) and lamina X (the central autonomic area), regions associated with autonomic outflow, as well as in lamina V. Retrograde labelling and dual immunolabelling with nNOS revealed that those AT1R-immunopositive cells in the IML were sympathetic preganglionic neurones, while those in lamina X were unlikely to be. Punctate labelling resembling that of axonal fibres and terminals was evident in lamina II of the dorsal horn and throughout the cord. Electron microscopy in the IML and lamina X revealed that these puncta were presynaptic terminals, but also astrocyte processes. Immunolabelling was also evident beneath the plasma membrane in neuronal somata. These data show that the AT1R in the spinal cord is ideally located to influence autonomic outflow and hence participate in the CNS determination of blood pressure.
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Affiliation(s)
- Zai Ahmad
- School of Biomedical Sciences, The Worsley Building, University of Leeds, Leeds LS2 9NQ, UK
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Bregonzio C, Armando I, Ando H, Jezova M, Baiardi G, Saavedra JM. Anti-inflammatory effects of angiotensin II AT1 receptor antagonism prevent stress-induced gastric injury. Am J Physiol Gastrointest Liver Physiol 2003; 285:G414-23. [PMID: 12686508 DOI: 10.1152/ajpgi.00058.2003] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Stress reduces gastric blood flow and produces acute gastric mucosal lesions. We studied the role of angiotensin II in gastric blood flow and gastric ulceration during stress. Spontaneously hypertensive rats were pretreated for 14 days with the AT1 receptor antagonist candesartan before cold-restraint stress. AT1 receptors were localized in the endothelium of arteries in the gastric mucosa and in all gastric layers. AT1 blockade increased gastric blood flow by 40-50%, prevented gastric ulcer formation by 70-80% after cold-restraint stress, reduced the increase in adrenomedullary epinephrine and tyrosine hydroxylase mRNA without preventing the stress-induced increase in adrenal corticosterone, decreased the stress-induced expression of TNF-alpha and that of the adhesion protein ICAM-1 in arterial endothelium, decreased the neutrophil infiltration in the gastric mucosa, and decreased the gastric content of PGE2. AT1 receptor blockers prevent stress-induced ulcerations by a combination of gastric blood flow protection, decreased sympathoadrenal activation, and anti-inflammatory effects (with reduction in TNF-alpha and ICAM-1 expression leading to reduced neutrophil infiltration) while maintaining the protective glucocorticoid effects and PGE2 release. Angiotensin II has a crucial role, through stimulation of AT1 receptors, in the production and progression of stress-induced gastric injury, and AT1 receptor antagonists could be of therapeutic benefit.
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Affiliation(s)
- Claudia Bregonzio
- Section on Pharmacology, National Institute of Mental Health, National Institute of Health, Department of Health and Human Services, Bethesda, MD 20892, USA.
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Jezova M, Armando I, Bregonzio C, Yu ZX, Qian S, Ferrans VJ, Imboden H, Saavedra JM. Angiotensin II AT(1) and AT(2) receptors contribute to maintain basal adrenomedullary norepinephrine synthesis and tyrosine hydroxylase transcription. Endocrinology 2003; 144:2092-101. [PMID: 12697718 DOI: 10.1210/en.2002-0019] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Angiotensin II (Ang II) AT(1) receptors have been proposed to mediate the Ang II-dependent and the stress-stimulated adrenomedullary catecholamine synthesis and release. However, in this tissue, most of the Ang II receptors are of the AT(2) type. We asked the question whether AT(1) and AT(2) receptors regulate basal catecholamine synthesis. Long-term AT(1) receptor blockade decreased adrenomedullary AT(1) receptor binding, AT(2) receptor binding and AT(2) receptor protein, rat tyrosine hydroxylase (TH) mRNA, norepinephrine (NE) content, Fos-related antigen 2 (Fra-2) protein, phosphorylated cAMP response element binding protein (pCREB), and ERK2. Long-term AT(2) receptor blockade decreased AT(2) receptor binding, TH mRNA, NE content and Fra-2 protein, although not affecting AT(1) receptor binding or receptor protein, pCREB or ERK2. Angiotensin II colocalized with AT(1) and AT(2) receptors in ganglion cell bodies. AT(2) receptors were clearly localized to many, but not all, chromaffin cells. Our data support the hypothesis of an AT(1)/AT(2) receptor cross-talk in the adrenomedullary ganglion cells, and a role for both receptor types on the selective regulation of basal NE, but not epinephrine formation, and in the regulation of basal TH transcription. Whereas AT(1) and AT(2) receptors involve the Fos-related antigen Fra-2, AT(1) receptor transcriptional effects include pCREB and ERK2, indicating common as well as different regulatory mechanisms for each receptor type.
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Affiliation(s)
- Miroslava Jezova
- Section on Pharmacology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Armando I, Jezova M, Juorio AV, Terrón JA, Falcón-Neri A, Semino-Mora C, Imboden H, Saavedra JM. Estrogen upregulates renal angiotensin II AT(2) receptors. Am J Physiol Renal Physiol 2002; 283:F934-43. [PMID: 12372768 DOI: 10.1152/ajprenal.00145.2002] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
AT(2) receptors may act in opposition to and in balance with AT(1) receptors, their stimulation having beneficial effects. We found renal AT(2) receptor expression in female mice higher than in male mice. We asked the question of whether such expression might be estrogen dependent. In male, female, ovariectomized, and estrogen-treated ovariectomized mice, we studied renal AT(1) and AT(2) receptors by immunocytochemistry and autoradiography, AT(2) receptor mRNA by RT-PCR, and cAMP, cGMP, and PGE(2) by RIA. AT(1) receptors predominated. AT(2) receptors were present in glomeruli, medullary rays, and inner medulla, and in female kidney capsule. AT(1) and AT(2) receptors colocalized in glomeruli. Female mice expressed fewer glomerular AT(1) receptors. Ovariectomy decreased AT(1) receptors in medullary rays and capsular AT(2) receptors. Estrogen administration normalized AT(1) receptors in medullary rays and increased AT(2) receptors predominantly in capsule and inner medulla, and also in glomeruli, medullary rays, and inner stripe of outer medulla. In medullas of estrogen-treated ovariectomized mice there was higher AT(2) receptor mRNA, decreased cGMP, and increased PGE(2) content. We propose that the protective effects of estrogen may be partially mediated through enhancement of AT(2) receptor stimulation.
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Affiliation(s)
- Ines Armando
- Section on Pharmacology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA.
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