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Zhu Y, Sun H, Wang H, Li N. Synaptic mechanisms underlying the elevated sympathetic outflow in fructose-induced hypertension. Front Physiol 2024; 15:1365594. [PMID: 38505704 PMCID: PMC10949223 DOI: 10.3389/fphys.2024.1365594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 02/05/2024] [Indexed: 03/21/2024] Open
Abstract
Metabolic syndrome is associated with cardiovascular dysfunction, including elevated sympathetic outflow. However, the underlying brain mechanisms are unclear. The nucleus tractus solitarius (NTS) critically regulates autonomic reflexes related to cardiovascular function and contains neurons projecting to the caudal ventrolateral medulla (CVLM). Nitric oxide (NO) is a diffusible free-radical messenger in the vascular, immune, and nervous systems. In this study, we determine if NO in the NTS is involved in the synaptic plasticity underlying the elevated sympathetic outflow in fructose-induced hypertension. We retrogradely labeled CVLM-projecting NTS neurons through the injection of FluoSpheres into the CVLM in a fructose-fed rat model to determine the cellular mechanism involved in increased sympathetic outflow. Fructose feeding increased the blood pressure and glucose levels, which represent metabolic syndrome. We found that fructose feeding reduces the NO precursor L-arginine-induced increase in the firing activity of CVLM-projecting NTS neurons. Furthermore, fructose feeding reduces the L-arginine-induced increase in presynaptic spontaneous glutamatergic synaptic inputs to NTS neurons, while NO donor DEA/NO produces an increase in glutamatergic synaptic inputs in fructose-fed rats similar to that in vehicle-treated rats. In addition, fructose feeding reduces the NO-induced depressor response and sympathoinhibition. These data suggested that fructose feeding reduced NO production and, thus, the subsequent NO-induced glutamate releases in the NTS and depressor response. The findings of this study provide new insights into the central mechanisms involved in the neural control of cardiovascular and autonomic functions in the NTS in metabolic syndrome.
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Affiliation(s)
- Yun Zhu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Haiying Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hongjie Wang
- Department of Anesthesiology, Affiliated Hospital of Hebei University, Baoding, China
| | - Na Li
- Department of Physiology, School of Basic Medical Sciences, Hebei University, Baoding, China
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Wu KLH, Wu CW, Tain YL, Chao YM, Hung CY, Tsai PC, Wang WS, Shih CD. Effects of high fructose intake on the development of hypertension in the spontaneously hypertensive rats: the role of AT 1R/gp91 PHOX signaling in the rostral ventrolateral medulla. J Nutr Biochem 2016; 41:73-83. [PMID: 28063367 DOI: 10.1016/j.jnutbio.2016.11.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 11/11/2016] [Accepted: 11/29/2016] [Indexed: 02/07/2023]
Abstract
Both genetic and dietary factors determine the development of hypertension. Whether dietary factor impacts the development of hereditary hypertension is unknown. Here, we evaluated the effect of daily high-fructose diet (HFD) on the development of hypertension in adolescent spontaneously hypertensive rats (SHR). Six-week-old SHR were randomly divided into two groups to receive HFD or normal diet (ND) for 3 weeks. The temporal profile of systolic blood pressure, alongside the sympathetic vasomotor activity, in the SHR-HFD showed significantly greater increases at 9-12 weeks of age compared with the age-matched SHR-ND group. Immunofluorescence was used to identify the distribution of reactive oxygen species (ROS), oxidants and antioxidants in rostral ventrolateral medulla (RVLM) where sympathetic premotor neurons reside. In RVLM of SHR-HFD, the levels of ROS accumulation and lipid peroxidation were elevated. The changes in protein expression were measured by Western blot. NADPH oxidase subunit gp91phox and angiotensin II type I receptor were up-regulated in RVLM neuron. On the other hand, the expression of extracellular superoxide dismutase was suppressed. Both molecular and hemodynamic changes in the SHR-HFD were rescued by oral pioglitazone treatment from weeks 7 to 9. Furthermore, central infusion with tempol, a ROS scavenger, effectively ameliorated ROS accumulation in RVLM and diminished the heightened pressor response and enhanced sympathetic activity in the SHR-HFD. Together, these results suggest that HFD intake at adolescent SHR may impact the development of hypertension via increasing oxidative stress in RVLM which could be effectively attenuated by pioglitazone treatment.
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Affiliation(s)
- Kay L H Wu
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China; Department of Senior Citizen Services, National Tainan Institute of Nursing, Tainan 700, Taiwan, Republic of China.
| | - Chih-Wei Wu
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China
| | - You-Lin Tain
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China; Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University, College of Medicine, Kaohsiung 833, Taiwan, Republic of China
| | - Yung-Mei Chao
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China
| | - Chun-Ying Hung
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China
| | - Pei-Chia Tsai
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China
| | - Wei-Sing Wang
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China
| | - Cheng-Dean Shih
- Department of Pharmacy, Graduate Institute of Pharmaceutical Technology, Tajen University, Pingtung County 90741, Taiwan, Republic of China.
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Abstract
Insufficient hepatic O2 in animal and human studies has been shown to elicit a hepatorenal reflex in response to increased hepatic adenosine, resulting in the stimulation of renal as well as muscle sympathetic nerve activity and activating the renin angiotensin system. Low hepatic ATP, hyperuricemia, and hepatic lipid accumulation reported in metabolic syndrome (MetS) patients may reflect insufficient hepatic O2 delivery, potentially accounting for the sympathetic overdrive associated with MetS. This theoretical concept is supported by experimental results in animals fed a high fructose diet to induce MetS. Hepatic fructose metabolism rapidly consumes ATP resulting in increased adenosine production and hyperuricemia as well as elevated renin release and sympathetic activity. This review makes the case for the hepatorenal reflex causing sympathetic overdrive and metabolic syndrome in response to exaggerated splanchnic oxygen consumption from excessive eating. This is strongly reinforced by the fact that MetS is cured in a matter of days in a significant percentage of patients by diet, bariatric surgery, or endoluminal sleeve, all of which would decrease splanchnic oxygen demand by limiting nutrient contact with the mucosa and reducing the nutrient load due to loss of appetite or dietary restriction.
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Affiliation(s)
- Michael D Wider
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
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4
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Abstract
Insufficient hepatic O2 in animal and human studies has been shown to elicit a hepatorenal reflex in response to increased hepatic adenosine, resulting in stimulation of renal as well as muscle sympathetic nerve activity and activating the renin angiotensin system. Low hepatic ATP, hyperuricemia, and hepatic lipid accumulation reported in metabolic syndrome (MetS) patients may reflect insufficient hepatic O2 delivery, potentially accounting for the sympathetic overdrive associated with MetS. This theoretical concept is supported by experimental results in animals fed a high fructose diet to induce MetS. Hepatic fructose metabolism rapidly consumes ATP resulting in increased adenosine production and hyperuricemia as well as elevated renin release and sympathetic activity. This review makes the case for the hepatorenal reflex causing sympathetic overdrive and metabolic syndrome in response to exaggerated splanchnic oxygen consumption from excessive eating. This is strongly reinforced by the fact that MetS is cured in a matter of days in a significant percentage of patients by diet, bariatric surgery, or endoluminal sleeve, all of which would decrease splanchnic oxygen demand by limiting nutrient contact with the mucosa and reducing the nutrient load due to the loss of appetite or dietary restriction.
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Affiliation(s)
- Michael D Wider
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
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Han J, Tan C, Wang Y, Yang S, Tan D. Betanin reduces the accumulation and cross-links of collagen in high-fructose-fed rat heart through inhibiting non-enzymatic glycation. Chem Biol Interact 2015; 227:37-44. [DOI: 10.1016/j.cbi.2014.12.032] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 12/17/2014] [Accepted: 12/19/2014] [Indexed: 10/24/2022]
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Wu KLH, Hung CY, Chan JYH, Wu CW. An increase in adenosine-5'-triphosphate (ATP) content in rostral ventrolateral medulla is engaged in the high fructose diet-induced hypertension. J Biomed Sci 2014; 21:8. [PMID: 24467657 PMCID: PMC3913325 DOI: 10.1186/1423-0127-21-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 01/20/2014] [Indexed: 12/21/2022] Open
Abstract
Background The increase in fructose ingestion has been linked to overdrive of sympathetic activity and hypertension associated with the metabolic syndrome. The premotor neurons for generation of sympathetic vasomotor activity reside in the rostral ventrolateral medulla (RVLM). Activation of RVLM results in sympathoexcitation and hypertension. Neurons in the central nervous system are able to utilize fructose as a carbon source of ATP production. We examined in this study whether fructose affects ATP content in RVLM and its significance in the increase in central sympathetic outflow and hypertension induced by the high fructose diet (HFD). Results In normotensive rats fed with high fructose diet (HFD) for 12 weeks, there was a significant increase in tissue ATP content in RVLM, accompanied by the increases in the sympathetic vasomotor activity and blood pressure. These changes were blunted by intracisternal infusion of an ATP synthase inhibitor, oligomycin, to the HFD-fed animals. In the catecholaminergic-containing N2a cells, fructose dose-dependently upregulated the expressions of glucose transporter 2 and 5 (GluT2, 5) and the rate-limiting enzyme of fructolysis, ketohexokinase (KHK), leading to the increases in pyruvate and ATP production, as well as the release of the neurotransmitter, dopamine. These cellular events were significantly prevented after the gene knocking down by lentiviral transfection of small hairpin RNA against KHK. Conclusion These results suggest that increases in ATP content in RVLM may be engaged in the augmented sympathetic vasomotor activity and hypertension associated with the metabolic syndrome induced by the HFD. At cellular level, the increase in pyruvate levels via fructolysis is involved in the fructose-induced ATP production and the release of neurotransmitter.
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Affiliation(s)
- Kay L H Wu
- Center for Translational Research in Biomedical Sciences, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung 83301, Taiwan.
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Mayer MA, Höcht C, Giani JF, Muñoz MC, Carranza A, Taira CA, Dominici FP, Puyó AM, Fernández BE. Central insulin-angiotensin II interaction in blood pressure regulation in fructose overloaded rats. ACTA ACUST UNITED AC 2013; 185:37-43. [PMID: 23816464 DOI: 10.1016/j.regpep.2013.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 03/17/2013] [Accepted: 06/20/2013] [Indexed: 10/26/2022]
Abstract
The aim of the present study was to determine if insulin is able to modulate the pressor response to intracerebroventricularly administered angiotensin II in insulin resistant fructose overloaded rats. Male Sprague-Dawley rats were divided into two groups: 1) Control group (C) with tap water to drink for 6 weeks (n=36); and 2) fructose treated (F), with fructose solution (10% w/v) to drink for 6 weeks (n=36). On the day of the experiment, anesthetized male C and F rats were intracerebroventricularly infused with insulin (12 mU/h, n=15) or Ringer's solution as vehicle (n=15) for 2h. Immediately, changes in mean arterial pressure (MAP) in response to an intracerebroventricular subpressor dose of angiotensin II (5 pmol, n=10) or vehicle (n=5) were measured for 10 min. Then, hypothalami were removed and Akt and ERK1/2 phosphorylation levels were determined. In a subset of C (n=10) and F (n=20) animals, PD98059 (p44/42 MAPK inhibitor) or vehicle was administered intracerebroventricularly at a flow rate of 5 μl/min for 1 min. Ten minutes later, insulin (12 mU/h, n=5 for each group) or vehicle (Ringer's solution, only in the F group, n=5) was perfused for 2h at a flow rate of 4 μl/h, and cardiovascular parameters were measured every 15 min. Immediately, changes in MAP and HR in response to a subpressor dose of Ang II (5 pmol/2 μl) were evaluated for 10 min (n=5 for each group). In other subset of animals (n=6 for each group), AT1 and AT2 hypothalamic receptor levels were measured by Western blotting. Intracerebroventricular insulin pre-treatment increased the pressor response to angiotensin II in C rats. In F rats (with or without insulin pretreatment), the pressor response to angiotensin II was higher than that in vehicle pre-treated C animals, but similar to that observed in C after insulin infusion. In C rats phospho-ERK 1/2 hypothalamic levels significantly increased after angiotensin II injection in insulin pretreated animals compared to vehicle pre-treated rats, suggesting that MAPK activation might be involved in insulin potentiation of blood pressure response to angiotensin II in the brain. Phospho-ERK 1/2 hypothalamic levels were significantly increased in vehicle treated F rats compared to C, suggesting that basal MAPK activation might play a role in the enhanced response to angiotensin II observed in these animals. Finally, in F rats, either after vehicle or insulin infusion, angiotensin II injection was associated with a similar increase in phospho-ERK 1/2 hypothalamic levels, comparable to that observed after angiotensin II injection in insulin pre-treated C animals. ERK 1/2 blockade significantly reduced MAP in F rats compared to C. Moreover, ERK 1/2 inhibition completely abolished the Ang II pressor response in F rats and in insulin pre-treated C animals. All these findings suggest that insulin-angiotensin II interaction at hypothalamic level might be involved in the increase in blood pressure observed in the insulin resistant state.
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Affiliation(s)
- M A Mayer
- Fundación CESIM, Santa Rosa, La Pampa, Argentina; Department of Pharmacology, School of Pharmacy and Biochemistry, University of Buenos Aires, Junin 956, (C1113AAD) Buenos Aires, Argentina; INFIBIOC, School of Pharmacy and Biochemistry, University of Buenos Aires, Junin 956, (C1113AAD) Buenos Aires, Argentina.
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C. García MD, C. Godoy Y, M. Celuch S. Impaired hypotensive responses induced by intrathecally injected drugs in fructose-fed rats. Eur J Pharmacol 2013; 706:17-24. [DOI: 10.1016/j.ejphar.2013.02.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 02/13/2013] [Accepted: 02/24/2013] [Indexed: 11/27/2022]
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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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Bertera F, Di Verniero CA, Mayer MA, Chiappetta D, Buontempo F, Polizio AH, Taira CA, Höcht C. Pharmacokinetic and pharmacodynamic properties of carvedilol in fructose hypertensive rats. Xenobiotica 2011; 42:206-19. [DOI: 10.3109/00498254.2011.604746] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Liao Q, Shi DH, Zheng W, Xu XJ, Yu YH. Antiproliferation of cardamonin is involved in mTOR on aortic smooth muscle cells in high fructose-induced insulin resistance rats. Eur J Pharmacol 2010; 641:179-86. [DOI: 10.1016/j.ejphar.2010.05.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 04/17/2010] [Accepted: 05/23/2010] [Indexed: 01/19/2023]
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Thaeomor A, Wyss JM, Jirakulsomchok D, Roysommuti S. High sugar intake via the renin-angiotensin system blunts the baroreceptor reflex in adult rats that were perinatally depleted of taurine. J Biomed Sci 2010; 17 Suppl 1:S30. [PMID: 20804606 PMCID: PMC2994397 DOI: 10.1186/1423-0127-17-s1-s30] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Perinatal taurine depletion leads to several physiological impairments in adult life, in part, due to taurine’s effects on the renin-angiotensin system, a crucial regulator of growth and differentiation during early life. The present study tests the hypothesis that perinatal taurine depletion predisposes adult female rats to impaired baroreceptor control of arterial pressure by altering the renin-angiotensin system. Female Sprague Dawley (SD) rats were fed normal rat chow and from conception to weaning drank 3% beta-alanine in water (taurine depletion, TD) or water alone (Control, C). Female offspring ate a normal rat chow and drank water with (G) or without (W) 5% glucose throughout the experiment. To test the possible role of the renin-angiotensin system, 50% of the rats received captopril (an angiotensin converting enzyme inhibitor, 400 mg/L) from 7 days before parameter measurements until the end of experiment. At 7-8 weeks of age, arterial pressure, heart rate, baroreflex control of heart rate and renal nerve activity were studied in either conscious, freely moving or anesthetized rats. Perinatal taurine depletion did not alter resting mean arterial pressure or heart rate in the adult female offspring that received either high or normal sugar intake. Captopril treatment slightly decreased mean arterial pressure but not heart rate in all groups. Compared to controls, only the TDG rats displayed blunted baroreflex responses. Captopril treatment normalized baroreflex sensitivity in TDG. The present data indicate that in perinatal taurine depleted female rats, the renin-angiotensin system underlines the ability of high sugar intake to blunt baroreceptor responses.
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Affiliation(s)
- Atcharaporn Thaeomor
- Department of Physiology Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
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Centrally administered insulin potentiates the pressor response to angiotensin II. ACTA ACUST UNITED AC 2010; 163:57-61. [DOI: 10.1016/j.regpep.2010.04.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 03/23/2010] [Accepted: 04/06/2010] [Indexed: 11/23/2022]
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Giani JF, Muñoz MC, Mayer MA, Veiras LC, Arranz C, Taira CA, Turyn D, Toblli JE, Dominici FP. Angiotensin-(1-7) improves cardiac remodeling and inhibits growth-promoting pathways in the heart of fructose-fed rats. Am J Physiol Heart Circ Physiol 2010; 298:H1003-13. [PMID: 20061544 DOI: 10.1152/ajpheart.00803.2009] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study examined whether chronic treatment with angiotensin (ANG)-(1-7) reduces cardiac remodeling and inhibits growth-promoting signaling pathways in the heart of fructose-fed rats (FFR), an animal model of insulin resistance. Sprague-Dawley rats were fed either normal rat chow (control) or the same diet plus 10% fructose in drinking water. For the last 2 wk of a 6-wk period of the corresponding diet, control and FFR were implanted with osmotic pumps that delivered ANG-(1-7) (100 ng.kg(-1).min(-1)). A subgroup of each group of animals (control or FFR) underwent a sham surgery. We determined heart weight, myocyte diameter, interstitial fibrosis, and perivascular collagen type III deposition as well as the phosphorylation degree of ERK1/2, JNK1/2, and p38MAPK. FFR showed a mild hypertension that was significantly reduced after ANG-(1-7) treatment. Also, FFR displayed higher ANG II circulating and local levels in the heart that remained unaltered after chronic ANG-(1-7) infusion. An increased heart-to-body weight ratio, myocyte diameter, as well as left ventricular fibrosis and perivascular collagen type III deposition were detected in the heart of FFR. Interestingly, significant improvements in these cardiac alterations were obtained after ANG-(1-7) treatment. Finally, FFR that received ANG-(1-7) chronically displayed significantly lower phosphorylation levels of ERK1/2, JNK1/2, and p38MAPK. The beneficial effects obtained by ANG-(1-7) were associated with normal values of Src-homology 2-containing protein-tyrosine phosphatase-1 (SHP-1) activity in the heart. In conclusion, chronic ANG-(1-7) treatment ameliorated cardiac hypertrophy and fibrosis and attenuated the growth-promoting pathways in the heart. These findings show an important protective role of ANG-(1-7) in the heart of insulin-resistant rats.
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Affiliation(s)
- Jorge F Giani
- Instituto de Química y Fisicoquímica Biológicas, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Tecnológicas of Argentina, Argentina
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Giani JF, Mayer MA, Muñoz MC, Silberman EA, Höcht C, Taira CA, Gironacci MM, Turyn D, Dominici FP. Chronic infusion of angiotensin-(1-7) improves insulin resistance and hypertension induced by a high-fructose diet in rats. Am J Physiol Endocrinol Metab 2009; 296:E262-71. [PMID: 19001546 DOI: 10.1152/ajpendo.90678.2008] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The current study was undertaken to determine whether Ang-(1-7) is effective in improving metabolic parameters in fructose-fed rats (FFR), a model of metabolic syndrome. Six-week-old male Sprague-Dawley rats were fed either normal rat chow (control) or the same diet plus 10% fructose in drinking water. For the last 2 wk of a 6-wk period of either diet, control and FFR were implanted with subcutaneous osmotic pumps that delivered Ang-(1-7) (100 ng.kg(-1).min(-1)). A subgroup of each group of animals (control or FFR) underwent a sham surgery. We measured systolic blood pressure (SBP) together with plasma levels of insulin, triglycerides, and glucose. A glucose tolerance test (GTT) was performed, with plasma insulin levels determined before and 15 and 120 min after glucose administration. In addition, we evaluated insulin signaling through the IR/IRS-1/PI3K/Akt pathway as well as the phosphorylation levels of IRS-1 at inhibitory site Ser(307) in skeletal muscle and adipose tissue. FFR displayed hypertriglyceridemia, hyperinsulinemia, increased SBP, and an exaggerated release of insulin during a GTT, together with decreased activation of insulin signaling through the IR/IRS-1/PI3K/Akt pathway in skeletal muscle, liver, and adipose tissue, as well as increased levels of IRS-1 phospho-Ser(307) in skeletal muscle and adipose tissue, alterations that correlated with increased activation of the kinases mTOR and JNK. Chronic Ang-(1-7) treatment resulted in normalization of all alterations. These results show that Ang-(1-7) ameliorates insulin resistance in a model of metabolic syndrome via a mechanism that could involve the modulation of insulin signaling.
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Affiliation(s)
- Jorge F Giani
- IQUIFIB, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, (1113) Buenos Aires, Argentina
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In Vitro and In Vivo Pharmacodynamic Properties of Metoprolol in Fructose-fed Hypertensive Rats. J Cardiovasc Pharmacol 2008; 51:532-41. [DOI: 10.1097/fjc.0b013e3181730306] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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