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Labban M, Itani MM, Maaliki D, Nasreddine L, Itani HA. The Sweet and Salty Dietary Face of Hypertension and Cardiovascular Disease in Lebanon. Front Physiol 2022; 12:802132. [PMID: 35153813 PMCID: PMC8835350 DOI: 10.3389/fphys.2021.802132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 12/20/2021] [Indexed: 12/11/2022] Open
Abstract
According to the World Health Organization (WHO), an estimated 1.28 billion adults aged 30–79 years worldwide have hypertension; and every year, hypertension takes 7.6 million lives. High intakes of salt and sugar (mainly fructose from added sugars) have been linked to the etiology of hypertension, and this may be particularly true for countries undergoing the nutrition transition, such as Lebanon. Salt-induced hypertension and fructose-induced hypertension are manifested in different mechanisms, including Inflammation, aldosterone-mineralocorticoid receptor pathway, aldosterone independent mineralocorticoid receptor pathway, renin-angiotensin system (RAS), sympathetic nervous system (SNS) activity, and genetic mechanisms. This review describes the evolution of hypertension and cardiovascular diseases (CVDs) in Lebanon and aims to elucidate potential mechanisms where salt and fructose work together to induce hypertension. These mechanisms increase salt absorption, decrease salt excretion, induce endogenous fructose production, activate fructose-insulin-salt interaction, and trigger oxidative stress, thus leading to hypertension. The review also provides an up-to-date appraisal of current intake levels of salt and fructose in Lebanon and their main food contributors. It identifies ongoing salt and sugar intake reduction strategies in Lebanon while acknowledging the country’s limited scope of regulation and legislation. Finally, the review concludes with proposed public health strategies and suggestions for future research, which can reduce the intake levels of salt and fructose levels and contribute to curbing the CVD epidemic in the country.
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Affiliation(s)
| | - Maha M Itani
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Dina Maaliki
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Lara Nasreddine
- Vascular Medicine Program, American University of Beirut Medical Center, Beirut, Lebanon.,Department of Nutrition and Food Sciences, Faculty of Agricultural and Food Sciences, American University of Beirut, Beirut, Lebanon
| | - Hana A Itani
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,Vascular Medicine Program, American University of Beirut Medical Center, Beirut, Lebanon.,Adjunct Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, United States
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2
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Rukavina Mikusic NL, Kouyoumdzian NM, Uceda A, Del Mauro JS, Pandolfo M, Gironacci MM, Puyó AM, Toblli JE, Fernández BE, Choi MR. Losartan prevents the imbalance between renal dopaminergic and renin angiotensin systems induced by fructose overload. l-Dopa/dopamine index as new potential biomarker of renal dysfunction. Metabolism 2018; 85:271-285. [PMID: 29727629 DOI: 10.1016/j.metabol.2018.04.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/28/2018] [Accepted: 04/25/2018] [Indexed: 01/03/2023]
Abstract
BACKGROUND The renin angiotensin system (RAS) and the renal dopaminergic system (RDS) act as autocrine and paracrine systems to regulate renal sodium management and inflammation and their alterations have been associated to hypertension and renal damage. Nearly 30-50% of hypertensive patients have insulin resistance (IR), with a strong correlation between hyperinsulinemia and microalbuminuria. OBJECTIVE The aim of this study was to demonstrate the existence of an imbalance between RAS and RDS associated to IR, hypertension and kidney damage induced by fructose overload (FO), as well as to establish their prevention, by pharmacological inhibition of RAS with losartan. MATERIALS/METHODS Ninety-six male Sprague-Dawley rats were randomly divided into four groups and studied at 4, 8 and 12 weeks: control group (C4, C8 and C12; tap water to drink); fructose-overloaded group (F4, F8 and F12; 10% w/v fructose solution to drink); losartan-treated control (L) group (L4, L8 and L12; losartan 30 mg/kg/day, in drinking water); and fructose-overloaded plus losartan group (F + L4, F + L8 and F + L12, in fructose solution). RESULTS FO induced metabolic and hemodynamic alterations as well as an imbalance between RAS and RDS, characterized by increased renal angiotensin II levels and AT1R overexpression, reduced urinary excretion of dopamine, increased excretion of l-dopa (increased l-dopa/dopamine index) and down-regulation of D1R and tubular dopamine transporters OCT-2, OCT-N1 and total OCTNs. This imbalance was accompanied by an overexpression of renal tubular Na+, K+-ATPase, pro-inflammatory (NF-kB, TNF-α, IL-6) and pro-fibrotic (TGF-β1 and collagen) markers and by renal damage (microalbuminuria and reduced nephrin expression). Losartan prevented the metabolic and hemodynamic alterations induced by FO from week 4. Increased urinary l-dopa/dopamine index and decreased D1R renal expression associated to FO were also prevented by losartan since week 4. The same pattern was observed for renal expression of OCTs/OCTNs, Na+, K+-ATPase, pro-inflammatory and pro-fibrotic markers from week 8. The appearance of microalbuminuria and reduced nephrin expression was prevented by losartan at week 12. CONCLUSION The results of this study provide new insight regarding the mechanisms by which a pro-hypertensive and pro-inflammatory system, such as RAS, downregulates another anti-hypertensive and anti-inflammatory system such as RDS. Additionally, we propose the use of l-dopa/dopamine index as a biochemical marker of renal dysfunction in conditions characterized by sodium retention, IR and/or hypertension, and as a predictor of response to treatment and follow-up of these processes.
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Affiliation(s)
- Natalia Lucía Rukavina Mikusic
- CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Cardiológicas (ININCA), Marcelo T. de Alvear 2270, C1122AAJ City of Buenos Aires (CABA), Buenos Aires, Argentina; Universidad de Buenos Aires, Instituto de Fisiopatología y Bioquímica Clínica (INFIBIOC), Junín 956, C1113AAD CABA, Buenos Aires, Argentina.
| | - Nicolás Martín Kouyoumdzian
- CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Cardiológicas (ININCA), Marcelo T. de Alvear 2270, C1122AAJ City of Buenos Aires (CABA), Buenos Aires, Argentina; Universidad de Buenos Aires, Instituto de Fisiopatología y Bioquímica Clínica (INFIBIOC), Junín 956, C1113AAD CABA, Buenos Aires, Argentina
| | - Ana Uceda
- Hospital Alemán, Laboratorio de Medicina Experimental, Av Pueyrredón 1640, C1118AAT CABA, Buenos Aires, Argentina
| | - Julieta Sofía Del Mauro
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Farmacología, Cátedra de Farmacología, Junín 956, C1113AAD CABA, Buenos Aires, Argentina
| | - Marcela Pandolfo
- Universidad de Buenos Aires, Instituto de Fisiopatología y Bioquímica Clínica (INFIBIOC), Junín 956, C1113AAD CABA, Buenos Aires, Argentina
| | - Mariela Mercedes Gironacci
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica, Junín 956, C1113AAD CABA, Buenos Aires, Argentina
| | - Ana María Puyó
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Anatomía e Histología, Junín 956, C1113AAD CABA, Buenos Aires, Argentina
| | - Jorge Eduardo Toblli
- CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Cardiológicas (ININCA), Marcelo T. de Alvear 2270, C1122AAJ City of Buenos Aires (CABA), Buenos Aires, Argentina; Hospital Alemán, Laboratorio de Medicina Experimental, Av Pueyrredón 1640, C1118AAT CABA, Buenos Aires, Argentina
| | - Belisario Enrique Fernández
- CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Cardiológicas (ININCA), Marcelo T. de Alvear 2270, C1122AAJ City of Buenos Aires (CABA), Buenos Aires, Argentina; Universidad de Buenos Aires, Instituto de Fisiopatología y Bioquímica Clínica (INFIBIOC), Junín 956, C1113AAD CABA, Buenos Aires, Argentina; Instituto Universitario de Ciencias de la Salud, Fundación H.A. Barceló, Av. Gral Las Heras 2191, C1127AAD CABA, Buenos Aires, Argentina
| | - Marcelo Roberto Choi
- CONICET, Universidad de Buenos Aires, Instituto de Investigaciones Cardiológicas (ININCA), Marcelo T. de Alvear 2270, C1122AAJ City of Buenos Aires (CABA), Buenos Aires, Argentina; Universidad de Buenos Aires, Instituto de Fisiopatología y Bioquímica Clínica (INFIBIOC), Junín 956, C1113AAD CABA, Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Anatomía e Histología, Junín 956, C1113AAD CABA, Buenos Aires, Argentina; Instituto Universitario de Ciencias de la Salud, Fundación H.A. Barceló, Av. Gral Las Heras 2191, C1127AAD CABA, Buenos Aires, Argentina
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Juarez E, Tufiño C, Querejeta E, Bracho-Valdes I, Bobadilla-Lugo RA. Evidence of changes in alpha-1/AT1 receptor function generated by diet-induced obesity. Diab Vasc Dis Res 2017; 14:485-493. [PMID: 28783954 DOI: 10.1177/1479164117722069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
To study whether hypercaloric diet-induced obesity deteriorates vascular contractility of rat aorta through functional changes in α1 adrenergic and/or AT1 Angiotensin II receptors. Angiotensin II- or phenylephrine-induced contraction was tested on isolated aorta rings with and without endothelium from female Wistar rats fed for 7 weeks with hypercaloric diet or standard diet. Vascular expression of Angiotensin II Receptor type 1 (AT1R), Angiotensin II Receptor type 2 (AT2R), Cyclooxygenase-1 (COX-1), Cyclooxygenase-2 (COX-2), inducible Nitric Oxide Synthase (iNOS) and endothelial Nitric Oxide Synthase (eNOS), as well as blood pressure, glucose, insulin and angiotensin II blood levels were measured. Diet-induced obesity did not significantly change agonist-induced contractions (Emax and pD2 hypercaloric diet vs standard diet n.s.d.) of both intact (e+) or endothelium free (e-) vessels but significantly decrease both phenylephrine and angiotensin II contraction (Emax p < 0.01 hypercaloric diet vs standard diet) in the presence of both prazosin and losartan but only in endothelium-intact vessels. Diet-induced obesity did not change angiotensin II AT1, AT2 receptor proteins expression but reduced COX-1 and NOS2 ( p < 0.05 vs standard diet). Seven-week hypercaloric diet-induced obesity produces alterations in vascular adrenergic and angiotensin II receptor dynamics that suggest an endothelium-dependent adrenergic/angiotensin II crosstalk. These changes reflect early-stage vascular responses to obesity.
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MESH Headings
- Adrenergic alpha-Agonists/pharmacology
- Adrenergic alpha-Antagonists/pharmacology
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Animals
- Aorta/drug effects
- Aorta/metabolism
- Aorta/physiopathology
- Cyclooxygenase 1/metabolism
- Cyclooxygenase 2/metabolism
- Diet/adverse effects
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/physiopathology
- Energy Intake
- Female
- In Vitro Techniques
- Membrane Proteins/metabolism
- Nitric Oxide Synthase Type II/metabolism
- Nitric Oxide Synthase Type III/metabolism
- Obesity/etiology
- Obesity/metabolism
- Obesity/physiopathology
- Rats, Wistar
- Receptor, Angiotensin, Type 1/drug effects
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/metabolism
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/metabolism
- Signal Transduction
- Time Factors
- Vasoconstriction/drug effects
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Affiliation(s)
- Esther Juarez
- 1 Post-graduate studies and Investigation Department, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Cecilia Tufiño
- 1 Post-graduate studies and Investigation Department, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Enrique Querejeta
- 1 Post-graduate studies and Investigation Department, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Ismael Bracho-Valdes
- 2 Institute of Experimental and Clinical Therapeutics, Department of Physiology, Health Sciences University Center, University of Guadalajara, Guadalajara, Jalisco, Mexico
| | - Rosa A Bobadilla-Lugo
- 1 Post-graduate studies and Investigation Department, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City, Mexico
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Bundalo MM, Zivkovic MD, Romic SD, Tepavcevic SN, Koricanac GB, Djuric TM, Stankovic AD. Fructose-rich diet induces gender-specific changes in expression of the renin-angiotensin system in rat heart and upregulates the ACE/AT1R axis in the male rat aorta. J Renin Angiotensin Aldosterone Syst 2016; 17:1470320316642915. [PMID: 27121972 PMCID: PMC5843877 DOI: 10.1177/1470320316642915] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 02/22/2016] [Indexed: 01/14/2023] Open
Abstract
Introduction: The cardiovascular renin–angiotensin system (RAS) could be affected by gender and dietary regime. We hypothesized that male rats will be more susceptible to activation of RAS in the heart and aorta, as a response to a fructose-rich diet (FRD). Materials and methods: Both male and female Wistar rats were given a 10% (w/v) fructose solution for 9 weeks. We measured the biochemical parameters, blood pressure (BP) and heart rate. We used Western blot and real-time polymerase chain reaction (PCR) to quantify protein and gene expression. Results: In the male rats, the FRD elevated BP and expression of cardiac angiotensin-converting enzyme (ACE), while the expression of angiotensin-converting enzyme 2 (ACE2) and angiotensin II Type 2 receptor (AT2R) were significantly decreased. In female rats, there were no changes in cardiac RAS expression due to FRD. Furthermore, the ACE/AT1R axis was overexpressed in the FRD male rats’ aortae, while only AT1R was upregulated in the FRD female rats’ aortae. ACE2 expression remained unchanged in the aortae of both genders receiving the FRD. Conclusions: The FRD induced gender-specific changes in the expression of the RAS in the heart and aortae of male rats. Further investigations are required in order to get a comprehensive understanding of the underlying mechanisms of gender-specific fructose-induced cardiovascular pathologies.
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Affiliation(s)
- Maja M Bundalo
- Laboratory for Radiobiology and Molecular Genetics, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Maja D Zivkovic
- Laboratory for Radiobiology and Molecular Genetics, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Snjezana Dj Romic
- Laboratory for Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Snezana N Tepavcevic
- Laboratory for Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Goran B Koricanac
- Laboratory for Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Tamara M Djuric
- Laboratory for Radiobiology and Molecular Genetics, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Aleksandra D Stankovic
- Laboratory for Radiobiology and Molecular Genetics, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
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Experimental gestational diabetes mellitus induces blunted vasoconstriction and functional changes in the rat aorta. BIOMED RESEARCH INTERNATIONAL 2014; 2014:329634. [PMID: 25610861 PMCID: PMC4291015 DOI: 10.1155/2014/329634] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 12/17/2014] [Indexed: 12/25/2022]
Abstract
Diabetic conditions increase vascular reactivity to angiotensin II in several studies but there are scarce reports on cardiovascular effects of hypercaloric diet (HD) induced gestational diabetes mellitus (GDM), so the objective of this work was to determine the effects of HD induced GDM on vascular responses. Angiotensin II as well as phenylephrine induced vascular contraction was tested in isolated aorta rings with and without endothelium from rats fed for 7 weeks (4 before and 3 weeks during pregnancy) with standard (SD) or hypercaloric (HD) diet. Also, protein expression of AT1R, AT2R, COX-1, COX-2, NOS-1, and NOS-3 and plasma glucose, insulin, and angiotensin II levels were measured. GDM impaired vasoconstrictor response (P < 0.05 versus SD) in intact (e+) but not in endothelium-free (e−) vessels. Losartan reduced GDM but not SD e− vasoconstriction (P < 0.01 versus SD). AT1R, AT2R, and COX-1 and COX-2 protein expression were significantly increased in GDM vessels (P < 0.05 versus SD). Results suggest an increased participation of endothelium vasodilator mediators, probably prostaglandins, as well as of AT2 vasodilator receptors as a compensatory mechanism for vasoconstrictor changes generated by experimental GDM. Considering the short term of rat pregnancy findings can reflect early stage GDM adaptations.
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Shum M, Pinard S, Guimond MO, Labbé SM, Roberge C, Baillargeon JP, Langlois MF, Alterman M, Wallinder C, Hallberg A, Carpentier AC, Gallo-Payet N. Angiotensin II type 2 receptor promotes adipocyte differentiation and restores adipocyte size in high-fat/high-fructose diet-induced insulin resistance in rats. Am J Physiol Endocrinol Metab 2013; 304:E197-210. [PMID: 23149621 PMCID: PMC3543572 DOI: 10.1152/ajpendo.00149.2012] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This study was aimed at establishing whether specific activation of angiotensin II (ANG II) type 2 receptor (AT2R) modulates adipocyte differentiation and function. In primary cultures of subcutaneous (SC) and retroperitoneal (RET) preadipocytes, both AT2R and AT1R were expressed at the mRNA and protein level. Cells were stimulated with ANG II or the AT2R agonist C21/M24, alone or in the presence of the AT1R antagonist losartan or the AT2R antagonist PD123,319. During differentiation, C21/M24 increased PPARγ expression in both RET and SC preadipocytes while the number of small lipid droplets and lipid accumulation solely increased in SC preadipocytes. In mature adipocytes, C21/M24 decreased the mean size of large lipid droplets. Upon abolishment of AT2R expression using AT2R-targeted shRNAs, expressions of AT2R, aP2, and PPARγ remained very low, and cells were unable to differentiate. In Wistar rats fed a 6-wk high-fat/high-fructose (HFHF) diet, a significant shift toward larger adipocytes was observed in RET and SC adipose tissue depots. C21/M24 treatments for 6 wk restored normal adipocyte size distribution in both these tissue depots. Moreover, C21/M24 and losartan decreased hyperinsulinemia and improved insulin sensitivity impaired by HFHF diet. A strong correlation between adipocyte size area and glucose infusion rate during euglycemic-hyperinsulinemic clamp was observed. These results indicate that AT2R is involved in early adipocyte differentiation, while in mature adipocytes and in a model of insulin resistance AT2R activation restores normal adipocyte morphology and improves insulin sensitivity.
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MESH Headings
- Adipocytes/drug effects
- Adipocytes/metabolism
- Adipocytes/pathology
- Adipocytes/physiology
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Animals
- Cell Differentiation/drug effects
- Cell Differentiation/genetics
- Cell Size/drug effects
- Cells, Cultured
- Diet, High-Fat/adverse effects
- Dietary Carbohydrates/adverse effects
- Dietary Fats/adverse effects
- Fructose/adverse effects
- Insulin Resistance/genetics
- Insulin Resistance/physiology
- Male
- RNA, Small Interfering/pharmacology
- Rats
- Rats, Wistar
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Receptor, Angiotensin, Type 2/physiology
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Affiliation(s)
- Michaël Shum
- Division of Endocrinology, Department of Medicine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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7
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Guimond MO, Wallinder C, Alterman M, Hallberg A, Gallo-Payet N. Comparative functional properties of two structurally similar selective nonpeptide drug-like ligands for the angiotensin II type-2 (AT2) receptor. Effects on neurite outgrowth in NG108-15 cells. Eur J Pharmacol 2013; 699:160-71. [DOI: 10.1016/j.ejphar.2012.11.032] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Revised: 11/11/2012] [Accepted: 11/13/2012] [Indexed: 01/12/2023]
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Zhou K, Kumar U, Yuen VG, McNeill JH. The effects of phentolamine on fructose-fed rats. Can J Physiol Pharmacol 2012; 90:1075-85. [DOI: 10.1139/y2012-063] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Metabolic syndrome (MS) is a combination of medical disorders that increase the risk of developing cardiovascular disease and diabetes. MS is associated with obesity, increased blood pressure, hyperlipidemia, and hyperglycemia. This study was designed to investigate the pharmacological profile of phentolamine, a nonselective α adrenergic receptor antagonist, in the prevention of increased blood pressure in fructose-fed rats. Phentolamine prevented the fructose-induced increase in systolic blood pressure without affecting insulin sensitivity and major metabolic parameters. The levels of plasma noradrenaline and angiotensin II, 2 proposed contributors to the development of fructose-induced elevated blood pressure, were examined. Neither noradrenaline nor angiotensin II levels were affected by phentolamine treatment. Since overproduction of nitric oxide has been shown to lead to an elevation in peroxynitrite, the role of oxidative stress, a proposed mechanism of fructose-induced elevated blood pressure and insulin resistance, was examined by measuring plasma levels of total nitrate/nitrite. Plasma nitrate/nitrite was significantly elevated in all fructose-fed animals, regardless of treatment with phentolamine. Another proposed contributor toward fructose-induced MS is an elevation in uric acid levels. In this experiment, plasma levels of uric acid were found to be increased by dietary fructose and were unaffected by phentolamine treatment.
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Affiliation(s)
- Kangbin Zhou
- The University of British Columbia, Faculty of Pharmaceutical Sciences, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada
| | - Ujendra Kumar
- The University of British Columbia, Faculty of Pharmaceutical Sciences, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada
| | - Violet G. Yuen
- The University of British Columbia, Faculty of Pharmaceutical Sciences, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada
| | - John H. McNeill
- The University of British Columbia, Faculty of Pharmaceutical Sciences, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada
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Abdulla MH, Sattar MA, Abdullah NA, Johns EJ. The effect of losartan and carvedilol on renal haemodynamics and altered metabolism in fructose-fed Sprague-Dawley rats. J Physiol Biochem 2012; 68:353-63. [PMID: 22281695 DOI: 10.1007/s13105-012-0147-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 01/11/2012] [Indexed: 12/31/2022]
Abstract
The aim of this study is to assess the effects of losartan and carvedilol on metabolic parameters and renal haemodynamic responses to angiotensin II (Ang II) and adrenergic agonists in the model of fructose-fed rat. Thirty-six Sprague-Dawley rats were fed for 8 weeks either 20% fructose solution (F) or tap water (C) ad libitum. F or C group received either losartan or carvedilol (10 mg/kg p.o.) daily for the last 3 weeks of the study (FL and L) and (FCV and CV), respectively, then in acute studies the renal vasoconstrictor actions of Ang II, noradrenaline (NA), phenylephrine (PE) and methoxamine (ME) were determined. Data, mean±SEM were analysed using ANOVA with significance at P <0.05. Losartan and carvedilol decreased the area under the glucose tolerance curve of the fructose-fed group. The responses (%) to NA, PE, ME and Ang II in F were lower (P <0.05) than C (F vs. C, 17±2 vs. 38±3; 24±2 vs. 48±2; 12±2 vs. 34±2; 17±2 vs. 26±2), respectively. L had higher (P <0.05) responses to NA and PE while CV had blunted (P <0.05) responses to NA, PE and Ang II compared to C (L, CV vs. C, 47±3, 9±2 vs. 38±3; 61±3, 29±3 vs. 48±2; 16±3, 4±3 vs. 26±2), respectively. FL but not FCV group had enhanced (P <0.05) responses to NA, PE and ME compared to F (FL vs. F, 33±3 vs. 17±2; 45±3 vs. 24±2; 26±3 vs. 12±2), respectively. Losartan and carvedilol had an important ameliorating effect on fructose-induced insulin resistance. Losartan treatment could be an effective tool to restore normal vascular reactivity in the renal circulation of the fructose-fed rat.
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Affiliation(s)
- Mohammed H Abdulla
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden 11800 Penang, Malaysia,
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10
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Soleimani M, Alborzi P. The role of salt in the pathogenesis of fructose-induced hypertension. Int J Nephrol 2011; 2011:392708. [PMID: 21789281 PMCID: PMC3140039 DOI: 10.4061/2011/392708] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 04/14/2011] [Accepted: 04/30/2011] [Indexed: 12/12/2022] Open
Abstract
Metabolic syndrome, as manifested by visceral obesity, hypertension, insulin resistance, and dyslipidemia, is reaching epidemic proportions in the Western World, specifically the United States. Epidemiologic studies suggest that the increased prevalence of metabolic syndrome directly correlates with an increase in the consumption of fructose, mainly in the form of high-fructose corn syrup. This inexpensive alternative to traditional sugar has been increasingly utilized by the food industry as a sweetener since the 1960s. While augmented caloric intake and sedentary lifestyles play important roles in the increasing prevalence of obesity, the pathogenesis of hypertension in metabolic syndrome remains controversial. One intriguing observation points to the role of salt in fructose-induced hypertension. Recent studies in rodents demonstrate that increased dietary fructose intake stimulates salt absorption in the small intestine and kidney tubules, resulting in a state of salt overload, thus setting in motion a cascade of events that will lead to hypertension. These studies point to a novel interaction between the fructose-absorbing transporter, Glut5, and the salt transporters, NHE3 and PAT1, in the intestine and kidney proximal tubule. This paper will focus on synergistic roles of fructose and salt in the pathogenesis of hypertension resulting from salt overload.
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Affiliation(s)
- Manoocher Soleimani
- The Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, 231 Albert Sabin Way, MSB 6312, Cincinnati, OH 45267-0585, USA
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Abstract
The worldwide increase in the incidence of metabolic syndrome correlates with marked increase in total fructose intake in the form of high-fructose corn syrup, beverage and table sugar. Increased dietary fructose intake in rodents has been shown to recapitulate many aspects of metabolic syndrome by causing hypertension, insulin resistance and hyperlipidaemia. Recent studies demonstrated that increased dietary fructose intake stimulates salt absorption in the small intestine and kidney tubules, resulting in a state of salt overload and thus causing hypertension. The absorption of salt (sodium and chloride) in the small intestine is predominantly mediated via the chloride/base exchangers DRA (Down Regulated in Adenoma) (SLC26A3) and PAT1 (Putative Anion Transporter 1) (SLC26A6), and the Na(+) /H(+) exchanger NHE3 (Sodium Hydrogen Exchanger3) (SLC9A3). PAT1 and NHE3 also co-localize on the apical membrane of kidney proximal tubule. Luminal fructose stimulated salt absorption in the jejunum and kidney tubules, responses that were significantly diminished in PAT1 null mice. These studies further demonstrated that Glut5 (SLC2A5) is the major fructose-absorbing transporter in the small intestine (and kidney proximal tubule) and plays an essential role in the systemic homeostasis of fructose. Increased dietary fructose intake for several weeks upregulated the expression of NHE3, PAT1 and Glut5 in the intestine and resulted in hypertension in wild-type mice, a response that was almost abolished in PAT1 null mice and abrogated in Glut5 null mice. This article will discuss the interaction of Glut5 with salt-absorbing transporters and review the role of dietary fructose in enhanced salt absorption in intestine and kidney as it relates to the pathogenesis of hypertension in metabolic syndrome.
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Affiliation(s)
- M Soleimani
- Center on Genetics of Transport and Epithelial Biology, Department of Medicine, University of Cincinnati, OH 45267-0585, USA.
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12
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Vasudevan H, Lau S, Jiang J, McNeill JH. Effects of insulin resistance and testosterone on the participation of cyclooxygenase isoforms in vascular reactivity. J Exp Pharmacol 2010; 2:169-79. [PMID: 27186103 PMCID: PMC4863301 DOI: 10.2147/jep.s14989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Testosterone plays an important role in mediating hypertension and altered vascular reactivity associated with insulin resistance. In addition to other pathways, testosterone-dependent changes in aortic cyclooxygenase (COX-2) mRNA levels affect blood pressure following insulin resistance. However their effects on vascular tone are unclear. We studied the changes in contraction response to phenylephrine (PE) in the aorta and superior mesenteric artery (SMA) from intact and gonadectomized fructose-fed rats. Constriction response to PE was studied in tissues incubated with the COX-1 and COX-2-selective antagonists, SC-560 and NS-398, respectively, and indomethacin, in addition to assessing its role in endothelium-dependent relaxation. Finally changes in COX-2 protein expression and plasma thromboxane A2 (TXA2), a downstream vasoconstrictor metabolite of COX-2, were measured. In fructose-fed rats, castration prevented the increase in blood pressure but not insulin resistance. The involvement of COX-2 in mediating the alpha-adrenergic vasoconstriction was higher in intact rat aorta compared to COX-1, which was prevented by castration. However, in the SMA, COX-2 participation was dependent on testosterone alone. Fructose-induced attenuation of endothelial relaxation was restored by indomethacin, which suggests a pro-vasoconstrictor role for COX. Both diet and testosterone did not alter vascular COX-2 expression thus suggesting the involvement of downstream testosterone-dependent pathways. This is supported by increased plasma TXA2 in the castrated rats compared to intact rats. Isoform-specific actions of COX are tissue-selective in states of insulin resistance and involve potential testosterone-dependent downstream targets. Further studies are needed to investigate the role of androgens and insulin resistance in vascular arachidonic acid metabolism.
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Affiliation(s)
- Harish Vasudevan
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sally Lau
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jihong Jiang
- Pediatric Oncology, Children and Women's Hospital, Child and Family Research Institute, Vancouver, British Columbia, Canada
| | - John H McNeill
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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13
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Mellor KM, Ritchie RH, Davidoff AJ, Delbridge LMD. Elevated dietary sugar and the heart: experimental models and myocardial remodeling. Can J Physiol Pharmacol 2010; 88:525-40. [PMID: 20555422 DOI: 10.1139/y10-005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A dramatic rise in the prevalence of insulin resistance has been paralleled by increasing dietary consumption of sugar. The use of added sweeteners containing fructose (sucrose and high-fructose corn syrup) has increased by 25% over the past 3 decades. High fructose intake has the potential to adversely influence systemic and cellular metabolism via insulin resistance and glycolytic dysregulation. As a tissue that is both insulin sensitive and glycolysis dependent, the heart may be especially vulnerable to fructose over-consumption. In this review, experimental studies of elevated dietary sugar intake are evaluated, including sucrose and fructose dietary manipulation models. The possible role of the GLUT5 transporter as a mediator of cardiomyocyte fructose uptake is considered. The impact of dietary sucrose and fructose on cardiac insulin-dependent signaling in the context of perturbed systemic metabolic response is detailed. Myocardial dysfunction, modified growth, and oxidative stress responses associated with high dietary sugar intake are discussed. Finally, the involvement of the renin-angiotensin system in mediating fructose cardiopathology is considered. This review highlights the importance of obtaining new mechanistic data that can contribute to a more developed understanding of how high sugar intake directly contributes to structural and functional cardiomyopathy.
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Affiliation(s)
- Kimberley M Mellor
- Department of Physiology, University of Melbourne, Melbourne, VIC 3010, Australia
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14
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Boccara F, Auclair M, Cohen A, Lefèvre C, Prot M, Bastard JP, Capeau J, Caron-Debarle M. HIV protease inhibitors activate the adipocyte renin angiotensin system. Antivir Ther 2010; 15:363-75. [DOI: 10.3851/imp1533] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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15
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Senador D, Key M, Brosnihan KB, Irigoyen MC, Elased KM, Morris M. Cardiovascular interactions between losartan and fructose in mice. J Cardiovasc Pharmacol Ther 2009; 15:68-77. [PMID: 19995939 DOI: 10.1177/1074248409351409] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
AIM To determine whether pharmacological blockade of angiotensin (Ang) AT1 receptors alters the cardiovascular, metabolic, and angiotensin-converting enzyme (ACE and ACE2) responses to a fructose diet in mice. METHODS C57BL male mice were fed with a 60% fructose diet for 8 weeks in combination with losartan treatment on week 9 (30 mg/kg per day). Blood pressure (BP), heart rate (HR), and autonomic balance were monitored using radiotelemetry with spectral analysis. Renal ACE and ACE2 activity and protein levels as well as Ang II and Ang 1-7 were measured. RESULTS Fructose impaired glucose tolerance and increased plasma cholesterol and insulin. These effects were not corrected by losartan treatment. Fructose increased BP and HR but only during the dark period. Short-term losartan treatment decreased BP by 16% in the fructose group but had no effect in controls. This was accompanied by a decrease in BP variance and its low-frequency component. Fructose increased Ang II (plasma and kidney) and ACE 2 (renal activity and protein expression). Losartan alone increased plasma Ang II in plasma and ACE2 in kidney. There were no changes in renal Ang 1-7 levels. CONCLUSIONS Losartan reversed the pressor effect of a high fructose diet, demonstrating that there are prominent interactions between a dietary regimen that produces glucose intolerance and an antihypertensive drug that antagonizes Ang signaling. The mechanism of change may be via renal Ang II rather than the ACE2/Ang 1-7 pathway because the fructose losartan combination resulted in lowered renal Ang II without changes in Ang 1-7.
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Affiliation(s)
- Danielle Senador
- Wright State University, Boonshoft School of Medicine, Dayton, OH 45435, USA.
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16
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High-fructose diet elevates myocardial superoxide generation in mice in the absence of cardiac hypertrophy. Nutrition 2009; 26:842-8. [PMID: 19932004 DOI: 10.1016/j.nut.2009.08.017] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 08/10/2009] [Accepted: 08/10/2009] [Indexed: 01/23/2023]
Abstract
OBJECTIVE Dietary fructose intake has increased considerably in recent decades and this has been paralleled by an increase in the incidence of insulin resistance, especially in children and adolescents. The impact of a high-fructose diet on the myocardium is not fully understood. The aims of this study were to characterize the murine metabolic and cardiac phenotypes associated with a high-fructose diet and to determine whether this diet imparts differential effects with age. METHODS Juvenile (4 wk) and adult (14 wk) C57Bl/6 mice were fed a 60% fructose diet or isoenergetic control (starch) diet for 6 wk. RESULTS At completion of the dietary intervention (at ages 10 and 20 wk), fructose-fed mice were normotensive; hyperinsulinemia and cardiac hypertrophy were not evident. Interestingly, fructose-fed mice exhibited lower blood glucose levels (10 wk: 4.81+/-0.28 versus 5.42+/-0.31 mmol/L; 20 wk: 4.88+/-0.30 versus 5.96+/-0.42 mmol/L, P<0.05) compared with controls. Nicotinamide adenosine dinucleotide phosphate-driven myocardial superoxide production was significantly increased in fructose-fed mice at both ages (by approximately 29% of control at 10 wk of age and 16% at 20 wk, P<0.01). No increase in aortic superoxide production was observed. Fructose feeding did not alter gene expression of the antioxidant thioredoxin-2, suggesting an imbalance between myocardial reactive oxygen species generation and antioxidant induction. CONCLUSION These findings indicate that increased myocardial superoxide production may represent an early and primary cardiac pathologic response to the metabolic challenge of excess dietary fructose in juveniles and adults that can be detected in the absence of cardiac hypertrophy and hypertension.
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Peredo H, Mayer M, Carranza A, Puyó A. Pioglitazone and Losartan Modify Hemodynamic and Metabolic Parameters and Vascular Prostanoids in Fructose-Overloaded Rats. Clin Exp Hypertens 2009; 30:159-69. [DOI: 10.1080/10641960801946889] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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18
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Tran LT, Yuen VG, McNeill JH. The fructose-fed rat: a review on the mechanisms of fructose-induced insulin resistance and hypertension. Mol Cell Biochem 2009; 332:145-59. [PMID: 19536638 DOI: 10.1007/s11010-009-0184-4] [Citation(s) in RCA: 258] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 06/09/2009] [Indexed: 02/07/2023]
Abstract
The metabolic syndrome is an important public health concern that predisposes individuals to the development of cardiovascular disease and/or Type 2 diabetes. The fructose-fed rat is an animal model of acquired systolic hypertension that displays numerous features of the metabolic syndrome. This animal model is used to study the relationship between insulin resistance/compensatory hyperinsulinemia and the development of hypertension. Several mechanisms have been proposed to mediate the link between insulin resistance and hypertension. In this review, we have addressed the role of sympathetic nervous system overactivation, increased production of vasoconstrictors, such as endothelin-1 and angiotensin II, and prostanoids in the development of hypertension in fructose-fed rats. The roles of nitric oxide, impaired endothelium-dependent relaxation and sex hormones in the pathogenesis of the fructose-fed induced hypertensive rats have also been highlighted. More recently, increased formation of reactive oxygen species and elevated levels of uric acid have been reported to contribute to fructose-induced hypertension.
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Affiliation(s)
- Linda T Tran
- Division of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3, Canada
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Singh AK, Amlal H, Haas PJ, Dringenberg U, Fussell S, Barone SL, Engelhardt R, Zuo J, Seidler U, Soleimani M. Fructose-induced hypertension: essential role of chloride and fructose absorbing transporters PAT1 and Glut5. Kidney Int 2008; 74:438-47. [PMID: 18496516 PMCID: PMC10947803 DOI: 10.1038/ki.2008.184] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Increased dietary fructose in rodents recapitulates many aspects of the Metabolic Syndrome with hypertension, insulin resistance and dyslipidemia. Here we show that fructose increased jejunal NaCl and water absorption which was significantly decreased in mice whose apical chloride/base exchanger Slc26a6 (PAT1, CFEX) was knocked out. Increased dietary fructose intake enhanced expression of this transporter as well as the fructose-absorbing transporter Slc2a5 (Glut5) in the small intestine of wild type mice. Fructose feeding decreased salt excretion by the kidney and resulted in hypertension, a response almost abolished in the knockout mice. In parallel studies, a chloride-free diet blocked fructose-induced hypertension in Sprague Dawley rats. Serum uric acid remained unchanged in animals on increased fructose intake with hypertension. We suggest that fructose-induced hypertension is likely caused by increased salt absorption by the intestine and kidney and the transporters Slc26a6 and Slc2a5 are essential in this process.
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Affiliation(s)
- Anurag Kumar Singh
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Hassane Amlal
- Department of Medicine, Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Patrick J. Haas
- Department of Medicine, Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Ulrike Dringenberg
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Stacey Fussell
- Department of Medicine, Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Sharon L. Barone
- Department of Medicine, Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Regina Engelhardt
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Jian Zuo
- Department of Developmental Neurobiology, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Manoocher Soleimani
- Department of Medicine, Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, Ohio, USA
- Research Services Department, Veterans Affairs Medical Center, Cincinnati, Ohio, USA
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Puyó AM, Mayer MA, Giorgi S, Gómez AH, Peredo HA. Noradrenaline and angiotensin II modify vascular prostanoid release in fructose-fed hypertensive rats. ACTA ACUST UNITED AC 2008; 27:161-5. [PMID: 18076476 DOI: 10.1111/j.1474-8673.2007.00409.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
1 A fructose-enriched diet induces hypertension, metabolic alterations and insulin resistance in rats, resembling human metabolic syndrome. Previously, we found that prostanoid production was altered in fructose-fed rats. 2 This study analysed the effects of incubation with noradrenaline (NA) and angiotensin II (Ang II) on prostanoid release in mesenteric vascular beds from control and fructose-fed rats. Animals which received fructose solution (10% w/v) for 22 weeks showed higher systolic blood pressure and triglyceridaemia. 3 In controls, NA increased 6-keto-prostaglandin (PG) F(1)alpha (prostacyclin metabolite) and thromboxane (TX) production. Ang II increased only TX release. In fructose-fed animals, NA increased 6-keto-PG F(1)alpha and TX. PGF(2)alpha (vasoconstrictor) was also elevated. Ang II also increased PGF(2)alpha and PGE(2) levels. 4 In conclusion, in fructose rats Ang II in vitro stimulates a vasoconstrictor prostanoid not stimulated in controls. This could be related to the observed in vivo blood pressure increase. In fructose-fed animals, NA and Ang II also augment vasodilator prostanoids, suggesting a compensatory mechanism because of long-term hypertension.
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Affiliation(s)
- A M Puyó
- Cátedras de Anatomía Humana (macro y microscópica), Instituto de Morfología J.J. Naón, Unidad de Neurosciencias; and 1a Cátedra de Anatomía, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
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21
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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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Farah V, Elased KM, Morris M. Genetic and dietary interactions: role of angiotensin AT1a receptors in response to a high-fructose diet. Am J Physiol Heart Circ Physiol 2007; 293:H1083-9. [PMID: 17449556 DOI: 10.1152/ajpheart.00106.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The renin-angiotensin system (RAS) has been implicated in the cardiovascular complications of diabetes. We showed that a high-fructose diet increases blood pressure and plasma angiotensin and impairs glucose tolerance. We investigated the role of angiotensin AT(1a) receptors in the development of fructose-induced cardiovascular and metabolic dysfunction. Male angiotensin AT(1a) knockout (AT1aKO) and wild-type (AT1aWT) mice with arterial telemetric catheters were fed a standard diet or one containing 60% fructose. Fructose increased mean arterial pressure (MAP) in AT1aWT but only during the dark phase (8% increase). In AT1aKO mice, fructose unexpectedly decreased MAP, during both light and dark periods (24 and 13% decrease, respectively). Analytical methods were used to measure systolic arterial pressure (SAP) and pulse interval (PI) variability in time and frequency domains. In fructose-fed AT1aWT mice, there was an increase in SAP variance and its low-frequency (LF) domain (11 +/- 3 vs. 23 +/- 4 mmHg(2), variance, and 7 +/- 2 vs. 17 +/- 3 mmHg(2), LF, control vs. fructose, P < 0.004). There were no changes in SAP variance in AT1aKO mice. Depressor responses to alpha(1)-adrenergic blockade were augmented in fructose-fed AT1a WT compared with AT1aKO mice. Fructose inhibited glucose tolerance with a greater effect in AT1aWT mice. Fructose increased plasma cholesterol in both groups (P < 0.01) and reduced ANG II in AT1aKO mice. Results document prominent interactions between genetics and diet with data showing that in the absence of angiotensin AT(1a) receptors, a fructose diet decreased blood pressure.
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MESH Headings
- Adrenergic alpha-1 Receptor Antagonists
- Adrenergic alpha-Antagonists/pharmacology
- Angiotensin II/blood
- Animals
- Blood Glucose/metabolism
- Blood Pressure
- Circadian Rhythm
- Dietary Carbohydrates
- Disease Models, Animal
- Fructose
- Glucose Intolerance/blood
- Glucose Intolerance/chemically induced
- Glucose Intolerance/genetics
- Glucose Intolerance/metabolism
- Glucose Intolerance/physiopathology
- Heart Rate
- Hypertension/blood
- Hypertension/chemically induced
- Hypertension/genetics
- Hypertension/metabolism
- Hypertension/physiopathology
- Insulin Resistance/genetics
- Lipids/blood
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Prazosin/pharmacology
- Receptor, Angiotensin, Type 1/deficiency
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptors, Adrenergic, alpha-1/metabolism
- Renin-Angiotensin System/genetics
- Signal Transduction/genetics
- Sympathetic Nervous System/drug effects
- Sympathetic Nervous System/metabolism
- Sympathetic Nervous System/physiopathology
- Time Factors
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Affiliation(s)
- Vera Farah
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Colonel Glenn Hwy, Dayton, OH 45435, USA
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Igarashi M, Hirata A, Nozaki H, Kadomoto-Antsuki Y, Tominaga M. Role of angiotensin II type-1 and type-2 receptors on vascular smooth muscle cell growth and glucose metabolism in diabetic rats. Diabetes Res Clin Pract 2007; 75:267-77. [PMID: 16934905 DOI: 10.1016/j.diabres.2006.06.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 06/07/2006] [Accepted: 06/26/2006] [Indexed: 12/31/2022]
Abstract
This study investigates the mechanisms whereby angiotensin II (Ang II) signaling contributes to cell growth and glucose metabolism in cultured vascular smooth muscle cells (VSMCs) from male Wistar fatty rats (WF) and their littermates (Wistar lean rats, WL). The levels of the medial outgrowth rate of VSMCs and Ang II type-1 receptors (AT1R) in aortae from WF were more enhanced than those in aortae from WL, but the level of Ang II type-2 receptors (AT2R) was not different. A mixture of insulin and Ang II additively increased the values of [(3)H]-thymidine incorporation in WF and WL, which was inhibited by olmesartan, an AT1 receptor blockade (ARB), but not by PD123,319, an AT2 receptor blockade. Similarly, insulin and Ang II phosphorylated extracellular-regulated protein kinase 1/2, retinoblastoma tumor suppressor protein, and cyclic AMP response element binding protein, and these levels were higher in WF than in WL. In contrast, the phosphorylation was suppressed by olmesartan but not PD123,319. Insulin-stimulated Akt phosphorylation and 2-deoxy-d-glucose uptake in WF were significantly reduced by Ang II, and the reduction was ameliorated by olmesartan but not PD123,319. Differently from the result of Akt, the phosphorylation of the insulin-stimulated insulin receptor beta-subunit was not affected by Ang II, olmesartan, or PD123,319. However, the phosphorylation of insulin-stimulated insulin-related substrate (IRS)-1 was suppressed by Ang II, and the suppression was ameliorated by olmesartan, but not PD123,319, in both WF and WL. In contrast, the phosphorylation of IRS-1 on Ser(307) was elevated by the Ang II, and the elevation was suppressed by olmesartan, but not by PD123,319, in both WF and WL. These findings demonstrated that Ang II signaling contributes to cell proliferation and inhibition of the insulin signaling pathways through AT1R, but not trough AT2R, in both non-diabetic and diabetic VSMCs.
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MESH Headings
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Angiotensin II Type 2 Receptor Blockers
- Animals
- Aorta/physiopathology
- Blood Glucose/metabolism
- Cells, Cultured
- DNA Replication
- Deoxyglucose/metabolism
- Diabetes Mellitus, Experimental/blood
- Diabetes Mellitus, Experimental/physiopathology
- Imidazoles/pharmacology
- Male
- Muscle, Smooth, Vascular/growth & development
- Muscle, Smooth, Vascular/physiopathology
- Nuclear Proteins/metabolism
- Obesity
- Rats
- Rats, Wistar
- Receptor, Angiotensin, Type 1/drug effects
- Receptor, Angiotensin, Type 1/physiology
- Receptor, Angiotensin, Type 2/drug effects
- Receptor, Angiotensin, Type 2/physiology
- Tetrazoles/pharmacology
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Affiliation(s)
- Masahiko Igarashi
- Department of Laboratory Medicine, Yamagata University School of Medicine, 2-2-2, Iida-nishi, Yamagata 990-9585, Japan.
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Abstract
PURPOSE OF REVIEW Nonalcoholic fatty liver disease and its subset nonalcoholic steatohepatitis represent the liver manifestations of insulin resistance. This review briefly summarizes advances in our understanding of the pathogenesis of nonalcoholic fatty liver disease and its prevalence, natural history and treatment. RECENT FINDINGS The recognition of the role the renin-angiotensin system in promoting insulin resistance is worth noting because of available drugs. Endoplasmic reticulum stress has also become a recent target of investigation because endoplasmic reticulum stress is common in obesity, diabetes and various forms of liver disease including nonalcoholic fatty liver disease. Endoplasmic reticulum stress may be responsible for activation of c-Jun kinase, a process that may cause the hepatocellular injury in nonalcoholic steatohepatitis. Progress has also been made in estimating the prevalence of nonalcoholic fatty liver disease in adults and children. Patients enrolled in the Dallas Heart Study were found to have a 33% prevalence of nonalcoholic fatty liver disease and children dying of accidental deaths in San Diego were found to have a 13% prevalence of nonalcoholic fatty liver disease. Because about 10% of people with nonalcoholic fatty liver disease are at risk for progressive fibrosis, the burden of this disease is now quite substantial. SUMMARY Incremental progress in understanding nonalcoholic fatty liver disease and nonalcoholic steatohepatitis promises to lead to new therapeutic options for this common disease.
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Affiliation(s)
- Brent A Neuschwander-Tetri
- Division of Gastroenterology and Hepatology, Saint Louis University Liver Center, St. Louis, Missouri 63110, USA.
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25
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Ernsberger P, Koletsky RJ. Metabolic actions of angiotensin receptor antagonists: PPAR-gamma agonist actions or a class effect? Curr Opin Pharmacol 2007; 7:140-5. [PMID: 17303473 PMCID: PMC2930911 DOI: 10.1016/j.coph.2006.11.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 11/03/2006] [Indexed: 10/23/2022]
Abstract
Accumulating basic and clinical data support the hypothesis that angiotensin receptor blockers have beneficial effects on glucose and lipid metabolism that are not shared by other classes of antihypertensive agents. These metabolic actions might only partially be shared by angiotensin-converting enzyme inhibitors. Specific benefits beyond those of other angiotensin receptor blockers have been claimed for telemesartan and, to a lesser extent, irbesartan based on a partial agonist action on PPAR-gamma receptors. Although the evidence is strong in vitro, specific actions not shared by other angiotensin receptor blockers have not yet been convincingly demonstrated in vivo or in clinical trials. In many cases, a full range of doses has not been compared, and the apparent superiority of telmesartan could be an artifact of its higher receptor binding affinity, greater tissue penetration owing to lipophilicity, and longer half life.
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Affiliation(s)
- Paul Ernsberger
- Department of Nutrition, Case Western Reserve University, School of Medicine, Cleveland, OH 44106-4906, USA.
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26
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Nyby MD, Abedi K, Smutko V, Eslami P, Tuck ML. Vascular Angiotensin Type 1 Receptor Expression Is Associated with Vascular Dysfunction, Oxidative Stress and Inflammation in Fructose-Fed Rats. Hypertens Res 2007; 30:451-7. [PMID: 17587757 DOI: 10.1291/hypres.30.451] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This study determined whether or not oxidative stress and vascular dysfunction in fructose-induced hyperinsulinemic rats are associated with activation of the vascular renin-angiotensin system (RAS). Four groups of rats were used. CONT rats were fed normal rat chow, CONT+CAP were fed normal rat chow and given 500 mg/L captopril in their drinking water, fructose-fed rats (FFR) were fed a high-fructose diet and FFR+CAP were fed the high-fructose diet plus captopril in water. After 8 weeks, the vascular reactivity of mesenteric artery segments was measured. Blood was analyzed for insulin, glucose, hydrogen peroxide and 8-isoprostane. Aortic and heart tissue were used for subjected to quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. Systolic blood pressure was significantly higher in FFR (p<0.05), and captopril treatment inhibited the blood pressure increase. Mesenteric artery dose-response curves to acetylcholine were shifted to the right in FFR (p<0.05) and were normal in FFR+CAP. Plasma insulin (p<0.05), hydrogen peroxide (p<0.02) and 8-isoprostane (p<0.05) were increased in FFR. Captopril treatment reducd hydrogen peroxide and 8-isoprostane concentrations. Aortic tissue mRNA expression levels were increased for angiotensin-converting enzyme (ACE, p<0.05), angiotensin type 1 receptor (AT1R, p<0.02), NOX4 (p<0.02) and VCAM-1 (p<0.05) in FFR aortic samples. Captopril treatment reduced AT1R, NOX4 and VCAM-1 expression in FFR to levels not different from CONT. Similar changes in heart tissue mRNA expression for angiotensinogen, AT1R and NOX4 were also observed. These results demonstrate that vascular RAS is upregulated in FFR and support the hypothesis that vascular RAS mediates vascular dysfunction and vascular oxidative stress in FFR.
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Affiliation(s)
- Michael D Nyby
- David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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Ernsberger P, Koletsky RJ. Metabolic effects of antihypertensive agents: role of sympathoadrenal and renin-angiotensin systems. Naunyn Schmiedebergs Arch Pharmacol 2006; 373:245-58. [PMID: 16783586 DOI: 10.1007/s00210-006-0080-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Accepted: 05/09/2006] [Indexed: 01/01/2023]
Abstract
Reports of beneficial, neutral and adverse impacts of antihypertensive drug classes on glucose and lipid metabolism can be found in human data. Furthermore, mechanisms for these diverse effects are often speculative and controversial. Clinical trial data on the metabolic effects of antihypertensive agents are highly contradictory. Comparisons of clinical trials involving different agents are complicated by differences in the spectrum of metabolic disturbances that accompany hypertension in different groups of patients. Two physiological systems are predominant at the interface between metabolic and cardiovascular regulation: the sympathetic nervous system (SNS) and the renin-angiotensin system (RAS). These two systems are major targets of antihypertensive drug actions, and also mediate many of the beneficial and adverse effects of antihypertensive agents on glucose and lipid metabolism. Thiazides and beta-adrenergic antagonists can adversely affect glucose and lipid metabolism, which are frequently compromised in human essential hypertension, and increase the incidence of new cases of diabetes. Laboratory studies confirm these effects, and suggest that compensatory activation of the SNS and RAS may be one mechanism. Other antihypertensives directly targeting the SNS and RAS may have beneficial effects on glucose and lipid metabolism, and may prevent diabetes. Resolution of the controversies surrounding the metabolic effects of antihypertensive agents can only be resolved by further laboratory studies, in addition to controlled clinical trials.
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Abstract
AIM Insulin resistance in patients is associated with increased atherosclerosis and arterial restenosis. It is thought that the concomitant hyperinsulinaemia exacerbates vascular disease because resistance to insulin-induced glucose disposal is associated with resistance to certain effects of insulin which inhibit, but with no resistance to other effects which promote, neointimal hyperplasia. We sought to determine the net effect of hyperinsulinaemia on neointimal hyperplasia in normal animals. METHODS Rats were infused with or without insulin for 16 days and the carotid artery injured by balloon catheter on day 2. RESULTS Steady-state serum insulin concentrations were 0.56 +/- 0.04 and 1.25 +/- 0.05 nm for control and hyperinsulinaemic rats respectively (p < 0.01). Systolic blood pressures, weights and serum glucose levels were not affected by hyperinsulinaemia. Fourteen days after injury, the neointima-to-media area ratio was 0.72 +/- 0.07 and 1.39 +/- 0.15 for control and hyperinsulinaemic rats respectively (p < 0.05). Media area was unaffected by hyperinsulinaemia. CONCLUSIONS The effects of hyperinsulinaemia which promote neointimal hyperplasia after balloon injury of rat carotid artery predominate over the effects which inhibit it even in normal animals.
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Affiliation(s)
- E Foster
- Division of Renal Diseases and Hypertension, Department of Medicine, The University of Texas Health Science Center, Houston Medical School, Houston, TX 77030, USA
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Hsieh PS. Reversal of fructose-induced hypertension and insulin resistance by chronic losartan treatment is independent of AT2 receptor activation in rats. J Hypertens 2005; 23:2209-17. [PMID: 16269963 DOI: 10.1097/01.hjh.0000189871.94031.e2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To examine whether angiotensin II type 2 receptors (AT2R) are involved in the reversal of fructose-induced hypertension and insulin resistance after chronic angiotensin II type 1 receptor (AT1R) blockade. METHODS Sprague-Dawley rats on fructose-enriched or regular diets were pretreated with losartan, an AT1R antagonist, or vehicle for 2 weeks before two-step glucose and insulin clamp experiments with [3-3H]glucose infusion. The hepatic glucose production (HGP) and whole-body glucose uptake (WBGU) were calculated during basal, euglycemic and euglycemic hyperinsulinemic periods. Blood pressure was measured before and after acute losartan (10 mg/kg, i.v. bolus), alone or in combination of PD123319 (PD, 50 microg/kg per min), an AT2R antagonist, or CGP42112 (2 microg/kg per min), an AT2R agonist, during the clamp study. RESULTS In rats on a regular diet, acute infusion of losartan alone or in combination with PD, an AT2R blocker, did not alter blood pressure and glucose metabolism during experiments. Fructose feeding for 6 weeks significantly increased blood pressure and attenuated insulin-mediated suppression of HGP and stimulation of WBGU. Both acute and chronic administration of losartan suppressed fructose-induced hypertension. Concomitant treatment with PD and losartan blunted the acute but not chronic losartan-mediated depressor effect. Acute losartan treatment further reduced insulin-induced suppression of HGP, but simultaneously increased insulin-stimulated WBGU. These acute metabolic effects of losartan were eliminated when PD was co-administered with losartan. Conversely, chronic losartan pretreatment significantly enhanced suppression of HGP and increased stimulation of WBGU by insulin, which were not altered when PD or CGP 42112 was superimposed on losartan during the clamp experiments. CONCLUSIONS These results suggest that reversal of high fructose-induced hypertension and insulin resistance by chronic losartan treatment is not dependent on AT2R activation and that functional activation of AT1R plays a major role in the pathogenesis of high fructose-induced hypertension and insulin resistance.
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Affiliation(s)
- Po-Shiuan Hsieh
- Department of Physiology and Biophysics, National Defense Medical Center, National Defense University, Taipei, Taiwan.
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