1
|
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.
Collapse
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
| |
Collapse
|
2
|
Bai JJ, Tan CD, Chow BKC. Secretin, at the hub of water-salt homeostasis. Am J Physiol Renal Physiol 2016; 312:F852-F860. [PMID: 27279485 DOI: 10.1152/ajprenal.00191.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 06/01/2016] [Indexed: 01/13/2023] Open
Abstract
Water and salt metabolism are tightly regulated processes. Maintaining this milieu intérieur within narrow limits is critical for normal physiological processes to take place. Disturbances to this balance can result in disease and even death. Some of the better-characterized regulators of water and salt homeostasis include angiotensin II, aldosterone, arginine vasopressin, and oxytocin. Although secretin (SCT) was first described >100 years ago, little is known about the role of this classic gastrointestinal hormone in the maintenance of water-salt homeostasis. In recent years, increasing body of evidence suggested that SCT and its receptor play important roles in the central nervous system and kidney to ensure that the mammalian extracellular fluid osmolarity is kept within a healthy range. In this review, we focus on recent advances in our understanding of the molecular, cellular, and network mechanisms by which SCT and its receptor mediate the control of osmotic homeostasis. Implications of hormonal cross talk and receptor-receptor interaction are highlighted.
Collapse
Affiliation(s)
- Jenny Juan Bai
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - Chong Da Tan
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - Billy K C Chow
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| |
Collapse
|
3
|
Chen G, Wang X, Zhang Y, Ru X, Zhou L, Tian Y. H3K9 histone methyltransferase G9a ameliorates dilated cardiomyopathy via the downregulation of cell adhesion molecules. Mol Med Rep 2015; 11:3872-9. [PMID: 25607239 DOI: 10.3892/mmr.2015.3218] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Accepted: 11/19/2014] [Indexed: 11/06/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is one of the leading causes of mortality; however, the underlying molecular mechanisms of DCM remain to be elucidated. H3K9 histone methyltransferase G9a has been previously characterized, although its functions in DCM are not yet understood. Cell adhesion molecules (CAM) are highly expressed in diseased human hearts and were thought to contribute to chronic degeneration in cardiac incompetence; however, it has been suggested that G9a may suppress the effects of CAM. The aim of the present study was to investigate whether G9a decreased the risk of DCM via regulation of CAM expression. A rat model of DCM was induced using furazolidone (FZ) treatment and numerous parameters were examined. G9a RNA interference (RNAi) was applied to primary neonatal cardiomyocytes (PNCs). Reverse transcription quantitative polymerase chain reaction and western blot analyses were used to examine the expression levels of G9a in the DCM model and PNCs. The growth rate of PNCs was evaluated following G9a RNAi and FZ treatment. The results confirmed that the expression levels of G9a were significantly decreased in the DCM model compared with those in the control group (P<0.01). Conversely, CAM expression levels were significantly increased in the DCM model compared with those in the control group (P<0.01). In PNCs, the expression of CAM was upregulated following G9a silencing using RNAi. Following three‑day culture, the growth rate of PNCs was inhibited by 70 and 35% following FZ treatment and G9a RNAi, respectively. In conclusion, G9a ameliorated DCM via downregulation of CAMs, therefore indicating its potential for use in the treatment of DCM.
Collapse
Affiliation(s)
- Guiying Chen
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
| | - Xu Wang
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
| | - Yina Zhang
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
| | - Xiaoxue Ru
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
| | - Lijun Zhou
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
| | - Ye Tian
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
| |
Collapse
|
4
|
Angiotensin II plasma levels are linked to disease severity and predict fatal outcomes in H7N9-infected patients. Nat Commun 2014; 5:3595. [PMID: 24800963 PMCID: PMC7091598 DOI: 10.1038/ncomms4595] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 03/07/2014] [Indexed: 02/07/2023] Open
Abstract
A novel influenza A (H7N9) virus of avian origin emerged in eastern China in the spring of 2013. This virus causes severe disease in humans, including acute and often lethal respiratory failure. As of January 2014, 275 cases of H7N9-infected patients had been reported, highlighting the urgency of identifying biomarkers for predicting disease severity and fatal outcomes. Here, we show that plasma levels of angiotensin II, a major regulatory peptide of the renin–angiotensin system, are markedly elevated in H7N9 patients and are associated with disease progression. Moreover, the sustained high levels of angiotensin II in these patients are strongly correlated with mortality. The predictive value of angiotensin II is higher than that of C-reactive protein and some clinical parameters such as the PaO2/FiO2 ratio (partial pressure of arterial oxygen to the fraction of inspired oxygen). Our findings indicate that angiotensin II is a biomarker for lethality in flu infections. An avian influenza H7N9 virus causes severe human disease, including acute and often lethal respiratory failure. Here, the authors report that plasma levels of angiotensin II, a regulatory peptide of the renin–angiotensin system, are associated with disease severity and fatal outcome in infected patients.![]()
Collapse
|
5
|
Soliman S, Ishrat T, Pillai A, Somanath PR, Ergul A, El-Remessy AB, Fagan SC. Candesartan induces a prolonged proangiogenic effect and augments endothelium-mediated neuroprotection after oxygen and glucose deprivation: role of vascular endothelial growth factors A and B. J Pharmacol Exp Ther 2014; 349:444-57. [PMID: 24681872 DOI: 10.1124/jpet.113.212613] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Angiogenesis is a key component of recovery after stroke. Angiotensin II receptor blocker (ARB) treatment improves neurobehavioral outcome and is associated with enhanced angiogenesis after stroke. The purpose of this study is to investigate the temporal pattern of the ARB proangiogenic effect in the ischemic brain and its association with vascular endothelial growth factors VEGF-A and VEGF-B. Wistar rats were exposed to 90-minute middle cerebral artery occlusion and treated with candesartan (1 mg/kg) at reperfusion. The proangiogenic potential of the cerebrospinal fluid was determined at 8, 24, 48, and 72 hours using an in vitro Matrigel tube formation assay. In addition, the expression of VEGF-A and VEGF-B was measured in brain homogenates using Western blotting at the same time points. A single candesartan dose induced a prolonged proangiogenic effect and a prolonged upregulation of VEGF-A and VEGF-B in vivo. In the ischemic hemisphere, candesartan treatment was associated with stabilization of hypoxia-inducible factor-1α and preservation of angiopoietin-1. The effect of ARB treatment on endothelial cells was studied in vitro. Our results identified brain endothelial cells as one target for the action of ARBs and a source of the upregulated VEGF-A and VEGF-B, which exerted an autocrine angiogenic response, in addition to a paracrine neuroprotective effect. Taken together, this study highlights the potential usefulness of augmenting the endogenous restorative capacity of the brain through the administration of ARBs.
Collapse
Affiliation(s)
- Sahar Soliman
- Program in Clinical and Experimental Therapeutics, University of Georgia, Augusta, Georgia (S.S., T.I., P.R.S., A.E., A.B.E., S.C.F.); Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia (S.S., T.I., P.R.S., A.E., A.B.E., S.C.F.); and Departments of Psychiatry (A.P.), Medicine (P.R.S.), Physiology (A.E.), Pharmacology and Toxicology (A.B.E.), and Neurology (S.C.F.), Georgia Regents University, Augusta, Georgia
| | | | | | | | | | | | | |
Collapse
|
6
|
Macova M, Armando I, Zhou J, Baiardi G, Tyurmin D, Larrayoz-Roldan IM, Saavedra JM. Estrogen reduces aldosterone, upregulates adrenal angiotensin II AT2 receptors and normalizes adrenomedullary Fra-2 in ovariectomized rats. Neuroendocrinology 2008; 88:276-86. [PMID: 18679017 PMCID: PMC2677380 DOI: 10.1159/000150977] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Accepted: 04/10/2008] [Indexed: 12/30/2022]
Abstract
We studied the effect of ovariectomy and estrogen replacement on expression of adrenal angiotensin II AT1 and AT2 receptors, aldosterone content, catecholamine synthesis, and the transcription factor Fos-related antigen 2 (Fra-2). Ovariectomy increased AT1 receptor expression in the adrenal zona glomerulosa and medulla, and decreased adrenomedullary catecholamine content and Fra-2 expression when compared to intact female rats. In the zona glomerulosa, estrogen replacement normalized AT1 receptor expression, decreased AT1B receptor mRNA, and increased AT2 receptor expression and mRNA. Estrogen treatment decreased adrenal aldosterone content. In the adrenal medulla, the effects of estrogen replacement were: normalized AT1 receptor expression, increased AT2 receptor expression, AT2 receptor mRNA, and tyrosine hydroxylase mRNA, and normalized Fra-2 expression and catecholamine content. We demonstrate that the constitutive adrenal expression of AT1 receptors, catecholamine synthesis and Fra-2 expression are partially under the control of reproductive hormones. Our results suggest that estrogen treatment decreases aldosterone production through AT1 receptor downregulation and AT2 receptor upregulation. AT2 receptor upregulation and modulation of Fra-2 expression may participate in the estrogen-dependent normalization of adrenomedullary catecholamine synthesis in ovariectomized rats. The AT2 receptor upregulation and the decrease in AT1 receptor function and in the production of the fluid-retentive, pro-inflammatory hormone aldosterone partially explain the protective effects of estrogen therapy.
Collapse
Affiliation(s)
- Miroslava Macova
- Section on Pharmacology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda, Md, USA
| | | | | | | | | | | | | |
Collapse
|
7
|
Llamas B, Contesse V, Guyonnet-Duperat V, Vaudry H, Mormède P, Moisan MP. QTL mapping for traits associated with stress neuroendocrine reactivity in rats. Mamm Genome 2006; 16:505-15. [PMID: 16151695 DOI: 10.1007/s00335-005-0022-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Accepted: 04/06/2005] [Indexed: 12/15/2022]
Abstract
In the present study we searched for quantitative trait loci (QTLs) that affect neuroendocrine stress responses in a 20-min restraint stress paradigm using Brown-Norway (BN) and Wistar-Kyoto-Hyperactive (WKHA) rats. These strains differed in their hypothalamic-pituitary-adrenal axis (plasma ACTH and corticosterone levels, thymus, and adrenal weights) and in their renin-angiotensin-aldosterone system reactivity (plasma renin activity, aldosterone concentration). We performed a whole-genome scan on a F2 progeny derived from a WKHA x BN intercross, which led to the identification of several QTLs linked to plasma renin activity (Sr6, Sr8, Sr11, and Sr12 on chromosomes RNO2, 3, 19, and 8, respectively), plasma aldosterone concentration (Sr7 and Sr9 on RNO2 and 5, respectively), and thymus weight (Sr10, Sr13, and Srl4 on RNO5, 10, and 16, respectively). The type 1b angiotensin II receptor gene (Agtrlb) maps within the confidence intervals of QTLs on RNO2 linked to plasma renin activity (Sr6, highly significant; LOD = 5.0) and to plasma aldosterone level (Sr7, suggestive; LOD = 2.0). In vitro studies of angiotensin II-induced release of aldosterone by adrenal glomerulosa cells revealed a lower receptor potency (log EC50 = -8.16 +/- 0.11 M) and efficiency (Emax = 453.3 +/- 25.9 pg/3 x 10(4) cells/24 h) in BN than in WKHA (log EC50 = -10.66 +/- 0.18 M; Emax = 573.1 +/- 15.3 pg/3 x 10(4) cells/24 h). Moreover, differences in Agtr1b mRNA abundance and sequence reinforce the putative role of the Agtr1b gene in the differential plasma renin stress reactivity between the two rat strains.
Collapse
Affiliation(s)
- Bastien Llamas
- Laboratoire Neurogénétique et Stress, INSERM U471/INRA UMR1243, Université Victor Segalen Bordeaux 2, Institut François Magendie, Rue Camille Saint Saens, 33077 Bordeaux cedex, France
| | | | | | | | | | | |
Collapse
|
8
|
Volpe M, Tocci G, Pagannone E. Angiotensin II-receptor antagonist in the treatment of hypertension. Curr Hypertens Rep 2006; 7:287-93. [PMID: 16061048 DOI: 10.1007/s11906-005-0027-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Effective treatment of high blood pressure levels represents a crucial point in reducing global cardiovascular risk, and several studies have clearly demonstrated a significant reduction in cardiovascular and renal morbidity and mortality with a more intensive blood pressure-lowering treatment. Other factors beyond blood pressure control may be important in reducing the risk related to hypertension. Pharmacologic agents blocking the renin-angiotensin system, in particular the angiotensin II-receptor blocker (ARB), a novel class of antihypertensive agents, represent an important addition to the therapeutic options for hypertension management, and recent large, international, randomized, trials have demonstrated that ARBs have clinical benefits across the spectrum of disease severity. In this article, we provide some evidence derived from these trials, supporting a role for ARBs in primary and secondary prevention of cardiovascular and renal disease, beyond blood pressure control.
Collapse
Affiliation(s)
- Massimo Volpe
- Division of Cardiology, II Faculty of Medicine, University of Rome La Sapienza, Ospedale Sant'Andrea, Via di Grottarossa, 1035-39, 00189 Rome, Italy.
| | | | | |
Collapse
|
9
|
Volpe M, Trimarco B. A Novel Molecule of the Angiotensin II Receptor Blocker Class. High Blood Press Cardiovasc Prev 2005. [DOI: 10.2165/00151642-200512020-00004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
|
10
|
Bédard S, Sicotte B, St-Louis J, Brochu M. Modulation of body fluids and angiotensin II receptors in a rat model of intra-uterine growth restriction. J Physiol 2004; 562:937-50. [PMID: 15539403 PMCID: PMC1665548 DOI: 10.1113/jphysiol.2004.064683] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We previously reported that sodium restriction during pregnancy reduces plasma volume expansion and promotes intra-uterine growth restriction (IUGR) in rats while it activates the renin-angiotensin-aldosterone system (RAAS). In the present study, we proceeded to determine whether expression of the two angiotensin II (ANGII) receptor subtypes (AT(1) and AT(2)) change in relation to maternal water-electrolyte homeostasis and fetal growth. To this end, pregnant (gestation day 15) and non-pregnant Sprague-Dawley rats were randomly assigned to two groups fed either normal, or Na(+)-restricted diets for 7 days. At the end of the treatment period, plasma aldosterone and renin activity as well as plasma and urine electrolytes were measured. Determinations for AT(1) and AT(2) mRNA and protein were made by RNase protection assay and photoaffinity labelling, respectively, using a number of tissues implicated in volume regulation and fetal growth. In non-pregnant rats, Na(+) restriction decreases Na(+) excretion without altering plasma volume, plasma Na(+) concentration or the expression of AT(1) and AT(2) mRNA or protein in the tissues examined. In normally fed pregnant rats when compared to non-pregnant controls, AT(1) mRNA increases in the hypothalamus as well as pituitary and declines in uterine arteries, while AT(1) protein decreases in the kidney and AT(2) mRNA declines in the adrenal cortex. In pregnant rats, Na(+) restriction induces a decrease in plasma Na(+), an increase in plasma urea, as well as a decline in renal urea and creatinine clearance rates. Protein levels for both AT(1) and AT(2) in the pituitary and AT(2) mRNA in the adrenal cortex are lower in the Na(+)-restricted pregnant group when compared to normally fed pregnant animals. Na(+) restriction also induces a decrease in AT(1) protein in the placenta. In conclusion, these results suggest that pregnancy may increase sensitivity to Na(+) depletion by the tissue-specific modulation of ANGII receptors. Finally, these receptors may be implicated in the IUGR response to low Na(+).
Collapse
Affiliation(s)
- Sophie Bédard
- Centre de Recherche, Department of Obstetrics-Gynecology, Université de Montréal, Hôpital Sainte-Justine, 3175 Côte Ste-Catherine, Montréal, Québec, Canada H3T 1C5
| | | | | | | |
Collapse
|
11
|
Widdop RE, Jones ES, Hannan RE, Gaspari TA. Angiotensin AT2 receptors: cardiovascular hope or hype? Br J Pharmacol 2003; 140:809-24. [PMID: 14530223 PMCID: PMC1574085 DOI: 10.1038/sj.bjp.0705448] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2003] [Revised: 06/30/2003] [Accepted: 07/10/2003] [Indexed: 02/02/2023] Open
Abstract
British Journal of Pharmacology (2003) 140, 809–824. doi:10.1038/sj.bjp.0705448
Collapse
Affiliation(s)
- Robert E Widdop
- Department of Pharmacology, Monash University, Melbourne, Victoria 3800, Australia.
| | | | | | | |
Collapse
|
12
|
Volpe M, Musumeci B, De Paolis P, Savoia C, Morganti A. Angiotensin II AT2 receptor subtype: an uprising frontier in cardiovascular disease? J Hypertens 2003; 21:1429-43. [PMID: 12872031 DOI: 10.1097/00004872-200308000-00001] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The renin-angiotensin system (RAS) plays a pivotal role in the regulation of fluid, electrolyte balance and blood pressure, and is a modulator of cellular growth and proliferation. Biological actions of RAS are linked to the binding of the effector molecule, angiotensin II (AngII), to specific membrane receptors, mostly the AT1 subtype and, to a lesser extent, other subtypes. Following the identification and characterization of the AT2 subtype receptor, it has been proposed that a complex interaction between AngII and its receptors may play an important role in the effects of RAS. In this paper current information on AngII subtype receptors--their structure, regulation and intracellular signalling--are reviewed, with a particular emphasis on the potential relevance for cardiovascular pathophysiology. In addition, we discuss modulation of expression of the AT2 receptor and its interaction with the AT1 receptor subtype, as well as the potential effects of this receptor on blood pressure regulation. A better understanding of the integrated effects of the AngII subtype receptors may help to elucidate the function of the RAS, as well as their participation in the mechanisms of cardiovascular disease and attendant therapeutic implications.
Collapse
Affiliation(s)
- Massimo Volpe
- Cattedra di Cardiologia, II Facoltà di Medicina, Dipartimento di Medicina Sperimentale e Patologia, Università La Sapienza, Rome, Italy.
| | | | | | | | | |
Collapse
|
13
|
De Paolis P, Porcellini A, Savoia C, Lombardi A, Gigante B, Frati G, Rubattu S, Musumeci B, Volpe M. Functional cross-talk between angiotensin II and epidermal growth factor receptors in NIH3T3 fibroblasts. J Hypertens 2002; 20:693-9. [PMID: 11910305 DOI: 10.1097/00004872-200204000-00027] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The main angiotensin (Ang) II subtype receptors (AT1R and AT2R) are involved in cellular growth processes and exert functionally antagonistic effects. OBJECTIVE To characterize the mechanisms by which Ang II receptors influence growth, by investigating the interactions between Ang II subtype receptors and epidermal growth factor (EGF) receptors on mitogen-activated protein kinase (MAPK) pathway activation. DESIGN AND METHODS The experiments were performed using a mouse fibroblast cell line, NIH3T3, by transient co-transfection with rat AT1R or AT2R expression vectors, or both. Extracellular-signal-regulated kinase (ERK)1/2 phosphorylation was analysed by western blot and the ERK activity was evaluated using PathDetect, an in-vivo signal transduction pathway trans-reporting system. Selective Ang II receptor antagonists (losartan for AT1R and PD123319 for AT2R) were used to investigate the contributions of each receptor to the response observed. RESULTS Our data show that, in this cellular model, both Ang II receptors phosphorylate ERK1/2. However, in the cells expressing AT1R, the EGF-induced MAPK pathway was enhanced in the presence of Ang II in a synergistic fashion. In contrast, a reduction of EGF-induced MAPK activation was observed in the cells expressing AT2R. In cells expressing both Ang II subtype receptors, Ang II promoted an enhancement of EGF-induced MAPK activation. However, in the presence of the AT1R antagonist, losartan, the effect of EGF was reduced. CONCLUSION These data indicate the existence of an opposite cross-talk of AT1R and AT2R with EGF receptors, and suggest a complex functional interaction between these pathways in the regulation of cellular growth processes.
Collapse
Affiliation(s)
- Paola De Paolis
- IRCSS Istituto Neurologico Mediterraneo Neuromed, Via Atinense 18, Località Camerelle, Pozzilli (Is), Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Saavedra JM, Armando I, Terrón JA, Falcón-Neri A, Jöhren O, Häuser W, Inagami T. Increased AT(1) receptors in adrenal gland of AT(2) receptor gene-disrupted mice. REGULATORY PEPTIDES 2001; 102:41-7. [PMID: 11600209 DOI: 10.1016/s0167-0115(01)00303-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Angiotensin II (Ang II) AT(2) receptor-gene disrupted mice have increased systemic blood pressure and response to exogenous Angiotensin II. To clarify the mechanism of these changes, we studied adrenal AT(1) receptor expression and mRNA by receptor autoradiography and in situ hybridization in female AT(2) receptor-gene disrupted mice (agtr 2-/-) and wild-type controls (agtr 2+/+). We found high expression of AT(1) receptor binding and mRNA in adrenal zona glomerulosa of female wild-type mice. AT(2) receptors and mRNA were highly expressed in adrenal medulla of wild-type mice, but were not detected in zona glomerulosa. There was no AT(2) receptor binding or mRNA in adrenal glands of AT(2) receptor-gene disrupted mice. In these animals, AT(1) receptor binding and mRNA were increased in adrenal zona glomerulosa and AT(1) receptor mRNA was increased in the adrenal medulla when compared with wild-type animals.The present data support the hypothesis of an interaction or cross talk between AT(2) and AT(1) receptors in adrenal gland. The significant increase in AT(1) receptor expression in the absence of AT(2) receptor transcription may be partially responsible for the increased blood pressure and for the enhanced response to exogenously administered Angiotensin II in this model.
Collapse
MESH Headings
- Adrenal Medulla/metabolism
- Angiotensin II/pharmacology
- Animals
- Autoradiography
- Blood Pressure/drug effects
- Female
- Gene Expression Regulation
- Genotype
- Imidazoles/pharmacology
- In Situ Hybridization
- Losartan/pharmacology
- Mice
- Mice, Inbred Strains
- Mice, Knockout
- Mice, Mutant Strains
- Pyridines/pharmacology
- RNA, Messenger/metabolism
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/deficiency
- Receptors, Angiotensin/genetics
- Receptors, Angiotensin/metabolism
- Transcription, Genetic
- Vasoconstrictor Agents/pharmacology
- Zona Glomerulosa/drug effects
- Zona Glomerulosa/metabolism
Collapse
Affiliation(s)
- J M Saavedra
- Section on Pharmacology, National Institute of Mental Health, 10 Center Drive MSC 1514, Building 10, Room 2D-57, Bethesda, MD 20892, USA.
| | | | | | | | | | | | | |
Collapse
|
15
|
Armando I, Carranza A, Nishimura Y, Hoe KL, Barontini M, Terrón JA, Falcón-Neri A, Ito T, Juorio AV, Saavedra JM. Peripheral administration of an angiotensin II AT(1) receptor antagonist decreases the hypothalamic-pituitary-adrenal response to isolation Stress. Endocrinology 2001; 142:3880-9. [PMID: 11517166 DOI: 10.1210/endo.142.9.8366] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Angiotensin II, which stimulates AT(1) receptors, is a brain and peripheral stress hormone. We pretreated rats with the AT(1) receptor antagonist candesartan for 13 d via sc-implanted osmotic minipumps, followed by 24-h isolation in individual metabolic cages. We measured angiotensin II receptor-type binding and mRNAs and tyrosine hydroxylase mRNA by quantitative autoradiography and in situ hybridization, catecholamines by HPLC, and hormones by RIA. Isolation increased AT(1) receptor binding in hypothalamic paraventricular nucleus as well as anterior pituitary ACTH, and decreased posterior pituitary AVP. Isolation stress also increased AT(1) receptor binding and AT(1B) mRNA in zona glomerulosa and AT(2) binding in adrenal medulla, adrenal catecholamines, tyrosine hydroxylase mRNA, aldosterone, and corticosterone. Candesartan blocked AT(1) binding in paraventricular nucleus and adrenal gland; prevented the isolation-induced alterations in pituitary ACTH and AVP and in adrenal corticosterone, aldosterone, and catecholamines; abolished the increase in AT(2) binding in adrenal medulla; and substantially decreased urinary AVP, corticosterone, aldosterone, and catecholamines during isolation. Peripheral pretreatment with an AT(1) receptor antagonist blocks brain and peripheral AT(1) receptors and inhibits the hypothalamic-pituitary-adrenal response to stress, suggesting a physiological role for peripheral and brain AT(1) receptors during stress and a possible beneficial effect of AT(1) antagonism in stress-related disorders.
Collapse
Affiliation(s)
- I Armando
- Centro de Investigaciones Endocrinologicas, Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires, Buenos Aires 1013, Argentina.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Rong P, Wilkinson-Berka JL, Skinner SL. Control of renin secretion from adrenal gland in transgenic Ren-2 and normal rats. Mol Cell Endocrinol 2001; 173:203-12. [PMID: 11223191 DOI: 10.1016/s0303-7207(00)00406-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In Ren-2 rats, plasma active renin and prorenin increase following binephrectomy (BNx) related to increasing plasma potassium. Adrenal is the source of the increasing prorenin but active renin comes mainly from thymus and gut. Trophic influences other than potassium were tested in the present work. Angiotensin did not influence the post-BNx increases in plasma active or prorenin but suppressed resting plasma prorenin from non-adrenal, non-renal sources virtually to zero. ACTH and histamine had no discernible effects. Hexamethonium decreased by 50% the post BNx increase in prorenin but not active renin. In Sprague-Dawley and spontaneously hypertensive rats, low levels of active renin secretion were detected from adrenal but no prorenin. Thus, in anesthetized Ren-2 rats, secreted prorenin is from two sources, i.e. extrarenal and extra-adrenal sites readily suppressible with angiotensin and the adrenal that is partly suppressible by autonomic blockage. This may assist in identifying the origin of extra-renal prorenin secreted in man.
Collapse
Affiliation(s)
- P Rong
- Department of Physiology, The University of Melbourne, Vic. 3010, Parkville, Australia
| | | | | |
Collapse
|
17
|
Otsuka F, Ogura T, Kataoka H, Kishida M, Takahashi M, Mimura Y, Yamauchi T, Makino H. Differential effect of chronic inhibition of calcium channel and angiotensin II type 1-receptor on aldosterone synthesis in spontaneously hypertensive rats. J Steroid Biochem Mol Biol 2000; 74:125-36. [PMID: 11086231 DOI: 10.1016/s0960-0760(00)00096-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We have investigated the in vivo effect of chronic blockade of Ca(2+)-channels and angiotensin II type 1 (AT(1))-receptors on aldosterone (Aldo)-synthesis in the adrenal glands of spontaneously hypertensive rats (SHR). Male SHR were administered Ca(2+)-antagonist, amlodipine (10 mg/kg per day) or AT(1)-receptor-antagonist, TCV-116 (1 mg/kg per day) from 7 until 11 weeks of age. Systolic blood pressure (SBP) and heart rate (HR) were significantly higher in SHR than Wistar-Kyoto (WKY) rats. Both treatments resulted in equivalent and significant reduction in SBP in SHR. Aldo-secretion in SHR, which was significantly higher than in WKY rats, was profoundly suppressed by TCV-116 compared with amlodipine. Both treatments resulted in thickening of the zona glomerulosa, which immunohistochemically contains Aldo, at the end of therapy. Competitive reverse transcription-polymerase chain reaction (RT-PCR) showed that CYP11A (P450scc) mRNA regulating the first step of Aldo-synthesis was significantly reduced from week 9 of age by amlodipine, and that CYP11B2 (P450aldo) mRNA regulating the last step of Aldo-synthesis was potently suppressed from 9 weeks of age by TCV-116. Our results indicate that chronic treatment with different antihypertensive agents directly modulates adrenocortical aldosterone synthesis in SHR in vivo via different mechanisms.
Collapse
Affiliation(s)
- F Otsuka
- Department of Medicine III, Okayama University Medical School, 2-5-1 Shikata-cho, 700-8558, Okayama, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
18
|
De Paolis P, Porcellini A, Gigante B, Giliberti R, Lombardi A, Savoia C, Rubattu S, Volpe M. Modulation of the AT2 subtype receptor gene activation and expression by the AT1 receptor in endothelial cells. J Hypertens 1999; 17:1873-7. [PMID: 10703883 DOI: 10.1097/00004872-199917121-00015] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To investigate whether angiotensin II type 2 (AT2) receptor (AT2-r) promoter activity and expression are modulated by angiotensin II (Ang II), and whether the AT1 receptor (AT1-r) is involved in this effect. DESIGN AND METHODS Primary endothelial cells obtained from NEONATAL rat aorta, expressing both receptors, were transfected with the rat AT2-r promoter region cloned into a pCAT-reporter vector. The reporter-expression study was performed in a transient transfection assay system. Transfected cells were studied following angiotensin-converting enzyme inhibition to prevent endogenous formation of Ang II. Cells were subsequently stimulated for 6 h with Ang II, either alone or in combination with the AT1-r antagonist DuP753. AT2-r mRNA was assessed by RNase protection assay during the same pharmacological stimuli. RESULTS Stimulation with Ang II caused an increase in promoter activity (+50%, P < 0.05 versus baseline), whereas mRNA expression was reduced by 50% (P < 0.05 versus baseline). Concomitant treatment with DuP753 and Ang II was associated with a 98% increase in promoter activity (P < 0.05 versus baseline). DuP753 also prevented the reduction in mRNA; it actually produced a 100% increase in AT2-r mRNA accumulation (P < 0.01 versus baseline). Studies with the AT2-r antagonist PD123319 indicate that the AT2-r is also involved in the regulation of AT2-r gene promoter activity. CONCLUSIONS These data indicate that Ang II increases AT2-r promoter activity and decreases AT2-r mRNA accumulation in endothelial cells. The AT1 subtype receptor is involved in the modulation of both effects of Ang II. These findings suggest that changes in the expression of AT2 receptors may occur during treatment with AT1-r antagonists, and they indicate the existence of a cross-talk between AT1 and AT2 receptors.
Collapse
MESH Headings
- Angiotensin II/pharmacology
- Angiotensin Receptor Antagonists
- Animals
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Gene Expression
- Gene Expression Regulation
- Imidazoles/pharmacology
- Losartan/pharmacology
- Promoter Regions, Genetic/drug effects
- Promoter Regions, Genetic/physiology
- Pyridines/pharmacology
- RNA, Messenger/antagonists & inhibitors
- Rats
- Rats, Inbred WKY
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/genetics
- Receptors, Angiotensin/physiology
- Transcriptional Activation
Collapse
Affiliation(s)
- P De Paolis
- IRCSS Istituto Neurologico Mediterraneo Neuromed, Pozzilli (Is), Italy
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Abstract
The object of this review is to describe the role of the renin-angiotensin system in control of aldosterone secretion. The review focuses on the roles of the circulating renin-angiotensin (RAS) system, the activity of which is determined predominantly by control of renin secretion from the kidney and on the role of the intra-adrenal RAS. Angiotensin can bind to two types of G protein coupled receptors, the AT1 and AT2 receptors. Both receptors are found on cells from the zona glomerulosa, the site of aldosterone synthesis. Angiotensin II acting via the AT1 receptor stimulates the synthesis of aldosterone at early and late steps in the pathway. Its effect on aldosterone is influenced by a number of other factors such as plasma potassium levels, sodium status, other peptides such as ANP and adrenomedullin and proadrenomedullin N-terminal peptide. All components of the RAS are found in the adrenal gland. The activity of this intra-adrenal RAS is unmasked and amplified in nephrectomised animals. Aldosterone controls sodium transport across epithelial cells, but recently novel effects on the heart have been described.
Collapse
Affiliation(s)
- E R Lumbers
- School of Physiology and Pharmacology, University of New South Wales, Sydney, Australia.
| |
Collapse
|