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Fejes R, Lutnik M, Weisshaar S, Pilat N, Wagner KH, Stüger HP, Peake JM, Woodman RJ, Croft KD, Bondonno CP, Hodgson JM, Wolzt M, Neubauer O. Increased nitrate intake from beetroot juice over 4 weeks affects nitrate metabolism, but not vascular function or blood pressure in older adults with hypertension. Food Funct 2024; 15:4065-4078. [PMID: 38546454 PMCID: PMC11034575 DOI: 10.1039/d3fo03749e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 03/24/2024] [Indexed: 04/23/2024]
Abstract
The decline in vascular function and increase in blood pressure with aging contribute to an increased cardiovascular disease risk. In this randomized placebo-controlled crossover study, we evaluated whether previously reported cardiovascular benefits of plant-derived inorganic nitrate via nitric oxide (NO) translate into improved vascular function and blood pressure-lowering in 15 men and women (age range: 56-71 years) with treated hypertension. We investigated the effects of a single ∼400 mg-dose at 3 hours post-ingestion (3H POST) and the daily consumption of 2 × ∼400 mg of nitrate through nitrate-rich compared with nitrate-depleted (placebo) beetroot juice over 4 weeks (4WK POST). Measurements included nitrate and nitrite in plasma and saliva; endothelial-dependent and -independent forearm blood flow (FBF) responses to acetylcholine (FBFACh) and glyceryltrinitrate (FBFGTN); and clinic-, home- and 24-hour ambulatory blood pressure. Compared to placebo, plasma and salivary nitrate and nitrite increased at 3H and 4WK POST following nitrate treatment (P < 0.01), suggesting a functioning nitrate-nitrite-NO pathway in the participants of this study. There were no differences between treatments in FBFACh and FBFGTN-area under the curve (AUC) ratios [AUC ratios after (3H POST, 4WK POST) compared with before (PRE) the intervention], or 24-hour ambulatory blood pressure or home blood pressure measures (P > 0.05). These findings do not support the hypothesis that an increased intake of dietary nitrate exerts sustained beneficial effects on FBF or blood pressure in hypertensive older adults, providing important information on the efficacy of nitrate-based interventions for healthy vascular aging. This study was registered under ClinicialTrials.gov (NCT04584372).
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Affiliation(s)
- Rebeka Fejes
- Department of Nutritional Sciences, Research Platform Active Ageing, University of Vienna, Vienna, Austria.
- Vienna Doctoral School of Pharmaceutical, Nutritional and Sport Sciences, University of Vienna, Vienna, Austria
| | - Martin Lutnik
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Stefan Weisshaar
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Nina Pilat
- Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Karl-Heinz Wagner
- Department of Nutritional Sciences, Research Platform Active Ageing, University of Vienna, Vienna, Austria.
| | - Hans-Peter Stüger
- Division Integrative Risk Assessment, Data and Statistics, Austrian Agency for Health and Food Safety, Vienna, Austria
| | - Jonathan M Peake
- School of Biomedical Sciences, Queensland University of Technology, Queensland, Australia
| | - Richard J Woodman
- Flinders Centre for Epidemiology and Biostatistics, Flinders University, Adelaide, South Australia, Australia
| | - Kevin D Croft
- Medical School, University of Western Australia, Royal Perth Hospital Unit, Perth, Western Australia, Australia
| | - Catherine P Bondonno
- Nutrition & Health Innovation Research Institute, School of Medical and Health Sciences, Royal Perth Hospital Research Foundation, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Jonathan M Hodgson
- Nutrition & Health Innovation Research Institute, School of Medical and Health Sciences, Royal Perth Hospital Research Foundation, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Michael Wolzt
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Oliver Neubauer
- Department of Nutritional Sciences, Research Platform Active Ageing, University of Vienna, Vienna, Austria.
- Centre for Health Sciences and Medicine, University for Continuing Education Krems, Krems, Austria
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Liu Y, Croft KD, Mori TA, Gaspari TA, Kemp-Harper BK, Ward NC. Long-term dietary nitrate supplementation slows the progression of established atherosclerosis in ApoE -/- mice fed a high fat diet. Eur J Nutr 2023; 62:1845-1857. [PMID: 36853380 PMCID: PMC10195750 DOI: 10.1007/s00394-023-03127-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 02/20/2023] [Indexed: 03/01/2023]
Abstract
BACKGROUND AND AIMS Atherosclerosis is associated with a reduction in the bioavailability and/or bioactivity of endogenous nitric oxide (NO). Dietary nitrate has been proposed as an alternate source when endogenous NO production is reduced. Our previous study demonstrated a protective effect of dietary nitrate on the development of atherosclerosis in the apoE-/- mouse model. However most patients do not present clinically until well after the disease is established. The aims of this study were to determine whether chronic dietary nitrate supplementation can prevent or reverse the progression of atherosclerosis after disease is already established, as well as to explore the underlying mechanism of these cardiovascular protective effects. METHODS 60 apoE-/- mice were given a high fat diet (HFD) for 12 weeks to allow for the development of atherosclerosis. The mice were then randomized to (i) control group (HFD + 1 mmol/kg/day NaCl), (ii) moderate-dose group (HFD +1 mmol/kg/day NaNO3), or (iii) high-dose group (HFD + 10 mmol/kg/day NaNO3) (20/group) for a further 12 weeks. A group of apoE-/- mice (n = 20) consumed a normal laboratory chow diet for 24 weeks and were included as a reference group. RESULTS Long-term supplementation with high dose nitrate resulted in ~ 50% reduction in plaque lesion area. Collagen expression and smooth muscle accumulation were increased, and lipid deposition and macrophage accumulation were reduced within atherosclerotic plaques of mice supplemented with high dose nitrate. These changes were associated with an increase in nitrite reductase as well as activation of the endogenous eNOS-NO pathway. CONCLUSION Long-term high dose nitrate significantly attenuated the progression of established atherosclerosis in the apoE-/- mice fed a HFD. This appears to be mediated in part through a XOR-dependent reduction of nitrate to NO, as well as enhanced eNOS activation via increased Akt and eNOS phosphorylation.
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Affiliation(s)
- Yang Liu
- School of Biomedical Sciences, University of Western Australia, Perth, WA Australia
| | - Kevin D. Croft
- School of Biomedical Sciences, University of Western Australia, Perth, WA Australia
| | - Trevor A. Mori
- Medical School, University of Western Australia, Perth, WA Australia
| | - Tracey A. Gaspari
- Department of Pharmacology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC Australia
| | - Barbara K. Kemp-Harper
- Department of Pharmacology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC Australia
| | - Natalie C. Ward
- Medical School, University of Western Australia, Perth, WA Australia
- Dobney Hypertension Centre, Medical School, University of Western Australia, G.P.O Box X2213, Perth, WA 6847 Australia
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Carvalho LRRA, Guimarães DD, Flôr AFL, Leite EG, Ruiz CR, de Andrade JT, Monteiro MMO, Balarini CM, Lucena RBD, Sandrim VC, Lundberg JO, Weitzberg E, Carlström M, Braga VDA. Effects of chronic dietary nitrate supplementation on longevity, vascular function and cancer incidence in rats. Redox Biol 2021; 48:102209. [PMID: 34915448 PMCID: PMC8683768 DOI: 10.1016/j.redox.2021.102209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 12/16/2022] Open
Abstract
RATIONALE Dietary nitrate and nitrite have a notoriously bad reputation because of their proposed association with disease, in particular cancer. However, more recent lines of research have challenged this dogma suggesting that intake of these anions also possess beneficial effects after in vivo conversion to the vital signaling molecule nitric oxide. Such effects include improvement in cardiovascular, renal and metabolic function, which is partly mediated via reduction of oxidative stress. A recent study even indicates that low dose of dietary nitrite extends life span in fruit flies. METHODS In this study, 200 middle-aged Wistar rats of both sexes were supplemented with nitrate or placebo in the drinking water throughout their remaining life and we studied longevity, biochemical markers of disease, vascular reactivity along with careful determination of the cause of death. RESULTS Dietary nitrate did not affect life span or the age-dependent changes in markers of oxidative stress, kidney and liver function, or lipid profile. Ex vivo examination of vascular function, however, showed improvements in endothelial function in rats treated with nitrate. Neoplasms were not more common in the nitrate group. CONCLUSION We conclude that chronic treatment with dietary nitrate does not affect life span in rats nor does it increase the incidence of cancer. In contrast, vascular function was improved by nitrate, possibly suggesting an increase in health span.
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Affiliation(s)
| | - Drielle D Guimarães
- Department of Physiology and Pharmacology - Karolinska Institutet, Stockholm, Sweden
| | | | - Ericka G Leite
- Department of Biotechnology - Federal University of Paraiba, João Pessoa, Brazil
| | - Clara R Ruiz
- Department of Biotechnology - Federal University of Paraiba, João Pessoa, Brazil
| | - Juliana T de Andrade
- Department of Biotechnology - Federal University of Paraiba, João Pessoa, Brazil
| | - Matheus M O Monteiro
- Department of Biotechnology - Federal University of Paraiba, João Pessoa, Brazil
| | - Camille M Balarini
- Department of Biotechnology - Federal University of Paraiba, João Pessoa, Brazil
| | | | | | - Jon O Lundberg
- Department of Physiology and Pharmacology - Karolinska Institutet, Stockholm, Sweden
| | - Eddie Weitzberg
- Department of Physiology and Pharmacology - Karolinska Institutet, Stockholm, Sweden
| | - Mattias Carlström
- Department of Physiology and Pharmacology - Karolinska Institutet, Stockholm, Sweden
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Liu Y, Croft KD, Caparros-Martin J, O'Gara F, Mori TA, Ward NC. Beneficial effects of inorganic nitrate in non-alcoholic fatty liver disease. Arch Biochem Biophys 2021; 711:109032. [PMID: 34520731 DOI: 10.1016/j.abb.2021.109032] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/08/2021] [Accepted: 09/08/2021] [Indexed: 12/12/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic representation of the metabolic disorders. Inorganic nitrate/nitrite can be converted to nitric oxide, regulate glucose metabolism, lower lipid levels, and reduce inflammation, thus raising the hypothesis that inorganic nitrate/nitrite could be beneficial for improving NAFLD. This study assessed the therapeutic effects of chronic dietary nitrate on NAFLD in a mouse model. 60 ApoE-/- mice were fed a high-fat diet (HFD) for 12 weeks to allow for the development of atherosclerosis with associated NAFLD. The mice were then randomly assigned to different groups (20/group) for a further 12 weeks: (i) HFD + NaCl (1 mmol/kg/day), (ii) HFD + NaNO3 (1 mmol/kg/day), and (iii) HFD + NaNO3 (10 mmol/kg/day). A fourth group of ApoE-/- mice consumed a normal chow diet for the duration of the study. At the end of the treatment, caecum contents, serum, and liver were collected. Consumption of the HFD resulted in significantly greater lipid accumulation in the liver compared to mice on the normal chow diet. Mice whose HFD was supplemented with dietary nitrate for the second half of the study, showed an attenuation in hepatic lipid accumulation. This was also associated with an increase in hepatic AMPK activity compared to mice on the HFD. In addition, a significant difference in bile acid profile was detected between mice on the HFD and those receiving the high dose nitrate supplemented HFD. In conclusion, dietary nitrate attenuates the progression of liver steatosis in ApoE-/- mice fed a HFD.
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Affiliation(s)
- Yang Liu
- School of Biomedical Sciences, University of Western Australia, Perth, WA, Australia
| | - Kevin D Croft
- School of Biomedical Sciences, University of Western Australia, Perth, WA, Australia
| | - Jose Caparros-Martin
- Wal-yan Respiratory Research Centre, Telethon Kids Institute, Perth, WA, Australia
| | - Fergal O'Gara
- Wal-yan Respiratory Research Centre, Telethon Kids Institute, Perth, WA, Australia; BIOMERIT Research Centre, School of Microbiology, University College Cork, T12 YN60, Cork, Ireland
| | - Trevor A Mori
- Medical School, University of Western Australia, Perth, WA, Australia
| | - Natalie C Ward
- Medical School, University of Western Australia, Perth, WA, Australia; Dobney Hypertension Centre, Medical School, University of Western Australia, Perth, WA, Australia.
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Morselli F, Faconti L, Mills CE, Morant S, Chowienczyk PJ, Yeung JA, Cavarape A, Cruickshank JK, Webb AJ. Dietary nitrate prevents progression of carotid subclinical atherosclerosis through blood pressure-independent mechanisms in patients with or at risk of type 2 diabetes mellitus. Br J Clin Pharmacol 2021; 87:4726-4736. [PMID: 33982797 DOI: 10.1111/bcp.14897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 04/30/2021] [Accepted: 05/09/2021] [Indexed: 12/01/2022] Open
Abstract
AIMS To test if 6 months' intervention with dietary nitrate and spironolactone could affect carotid subclinical atherosclerosis and stiffness, respectively, vs. placebo/doxazosin, to control for blood pressure (BP). METHODS A subgroup of participants in our double-blind, randomized-controlled, factorial VaSera trial had carotid imaging. Patients with hypertension and with/at risk of type 2 diabetes were randomized to active nitrate-containing beetroot juice or placebo nitrate-depleted juice, and spironolactone or doxazosin. Vascular ultrasound for carotid diameter (CD, mm) and intima-media thickness (CIMT, mm) was performed at baseline, 3- and 6-months. Carotid local stiffness (CS, m/s) was estimated from aortic pulse pressure (Arteriograph) and carotid lumen area. Data were analysed by modified intention to treat and using mixed-model effect, adjusted for confounders. RESULTS In total, 93 subjects had a baseline evaluation and 86% had follow-up data. No statistical interactions occurred between the juice and drug arms and BP was similar between the juices and between the drugs. Nitrate-containing vs. placebo juice significantly lowered CIMT (-0.06 [95% confidence interval -0.12, -0.01], P = .034), an overall difference of ~8% relative to baseline; but had no effect on CD or CS. Doxazosin appeared to reduce CS from baseline (-0.34 [-0.62, -0.06]) however, no difference was detected vs. spironolactone (-0.15 [-0.46, 0.16]). No differences were detected between spironolactone or doxazosin on CIMT and CD. CONCLUSIONS Our results show that 6 months' intervention with dietary nitrate influences vascular remodelling, but not carotid stiffness or diameter. Neither spironolactone nor doxazosin had a BP-independent effect on carotid structure and function.
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Affiliation(s)
- Franca Morselli
- Department of Clinical Pharmacology, King's College London British Heart Foundation Centre, School of Cardiovascular Medicine and Sciences, UK.,Dipartimento di Area Medica, Clinica Medica, Universita' degli Studi di Udine, Udine, Italy.,Biomedical Research Centre, Clinical Research Facility, 4th Floor, North Wing, St Thomas' Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Luca Faconti
- Department of Clinical Pharmacology, King's College London British Heart Foundation Centre, School of Cardiovascular Medicine and Sciences, UK.,Biomedical Research Centre, Clinical Research Facility, 4th Floor, North Wing, St Thomas' Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Charlotte E Mills
- King's College London, Department of Nutritional Sciences, School of Life Course Sciences, London, UK.,Department of Food and Nutritional Sciences, School of Chemistry, Food and Pharmacy, University of Reading, Reading, UK.,Biomedical Research Centre, Clinical Research Facility, 4th Floor, North Wing, St Thomas' Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Steven Morant
- Medicines Monitoring Unit (MEMO), University of Dundee, UK
| | - Philip J Chowienczyk
- Department of Clinical Pharmacology, King's College London British Heart Foundation Centre, School of Cardiovascular Medicine and Sciences, UK.,King's College London, Department of Nutritional Sciences, School of Life Course Sciences, London, UK.,Biomedical Research Centre, Clinical Research Facility, 4th Floor, North Wing, St Thomas' Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Joshua Au Yeung
- Department of Clinical Pharmacology, King's College London British Heart Foundation Centre, School of Cardiovascular Medicine and Sciences, UK.,Biomedical Research Centre, Clinical Research Facility, 4th Floor, North Wing, St Thomas' Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Alessandro Cavarape
- Dipartimento di Area Medica, Clinica Medica, Universita' degli Studi di Udine, Udine, Italy
| | - J Kennedy Cruickshank
- King's College London, Department of Nutritional Sciences, School of Life Course Sciences, London, UK.,Biomedical Research Centre, Clinical Research Facility, 4th Floor, North Wing, St Thomas' Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Andrew J Webb
- Department of Clinical Pharmacology, King's College London British Heart Foundation Centre, School of Cardiovascular Medicine and Sciences, UK.,Biomedical Research Centre, Clinical Research Facility, 4th Floor, North Wing, St Thomas' Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK
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6
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Zhang JQJ, Saravanabavan S, Cheng KM, Raghubanshi A, Chandra AN, Munt A, Rayner B, Zhang Y, Chau K, Wong ATY, Rangan GK. Long-term dietary nitrate supplementation does not reduce renal cyst growth in experimental autosomal dominant polycystic kidney disease. PLoS One 2021; 16:e0248400. [PMID: 33886581 PMCID: PMC8061912 DOI: 10.1371/journal.pone.0248400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 02/26/2021] [Indexed: 11/18/2022] Open
Abstract
Augmentation of endogenous nitric oxide (NO) synthesis, either by the classical L-arginine-NO synthase pathway, or the recently discovered entero-salivary nitrate-nitrite-NO system, may slow the progression of autosomal dominant polycystic kidney disease (ADPKD). To test this hypothesis, the expression of NO in human ADPKD cell lines (WT 9–7, WT 9–12), and the effect of L-arginine on an in vitro model of three-dimensional cyst growth using MDCK cells, was examined. In addition, groups of homozygous Pkd1RC/RC mice (a hypomorphic genetic ortholog of ADPKD) received either low, moderate or high dose sodium nitrate (0.1, 1 or 10 mmol/kg/day), or sodium chloride (vehicle; 10 mmol/kg/day), supplemented drinking water from postnatal month 1 to 9 (n = 12 per group). In vitro, intracellular NO, as assessed by DAF-2/DA fluorescence, was reduced by >70% in human ADPKD cell lines, and L-arginine and the NO donor, sodium nitroprusside, both attenuated in vitro cyst growth by up to 18%. In contrast, in Pkd1RC/RC mice, sodium nitrate supplementation increased serum nitrate/nitrite levels by ~25-fold in the high dose group (P<0.001), but kidney enlargement and percentage cyst area was not altered, regardless of dose. In conclusion, L-arginine has mild direct efficacy on reducing renal cyst growth in vitro, whereas long-term sodium nitrate supplementation was ineffective in vivo. These data suggest that the bioconversion of dietary nitrate to NO by the entero-salivary pathway may not be sufficient to influence the progression of renal cyst growth in ADPKD.
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Affiliation(s)
- Jennifer Q. J. Zhang
- Centre for Transplant and Renal Research, Westmead Institute for Medical Research, The University of Sydney, Sydney, New South Wales, Australia
- Department of Renal Medicine, Westmead Hospital, Western Sydney Local Health District, Sydney, New South Wales, Australia
| | - Sayanthooran Saravanabavan
- Centre for Transplant and Renal Research, Westmead Institute for Medical Research, The University of Sydney, Sydney, New South Wales, Australia
- Department of Renal Medicine, Westmead Hospital, Western Sydney Local Health District, Sydney, New South Wales, Australia
| | - Kai Man Cheng
- Centre for Transplant and Renal Research, Westmead Institute for Medical Research, The University of Sydney, Sydney, New South Wales, Australia
- Department of Renal Medicine, Westmead Hospital, Western Sydney Local Health District, Sydney, New South Wales, Australia
| | - Aarya Raghubanshi
- Centre for Transplant and Renal Research, Westmead Institute for Medical Research, The University of Sydney, Sydney, New South Wales, Australia
- Department of Renal Medicine, Westmead Hospital, Western Sydney Local Health District, Sydney, New South Wales, Australia
| | - Ashley N. Chandra
- Centre for Transplant and Renal Research, Westmead Institute for Medical Research, The University of Sydney, Sydney, New South Wales, Australia
- Department of Renal Medicine, Westmead Hospital, Western Sydney Local Health District, Sydney, New South Wales, Australia
| | - Alexandra Munt
- Centre for Transplant and Renal Research, Westmead Institute for Medical Research, The University of Sydney, Sydney, New South Wales, Australia
- Department of Renal Medicine, Westmead Hospital, Western Sydney Local Health District, Sydney, New South Wales, Australia
| | - Benjamin Rayner
- Heart Research Institute, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Yunjia Zhang
- Heart Research Institute, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Katrina Chau
- Department of Renal Medicine and School of Medicine, Western Sydney University at Blacktown Hospital, Sydney, New South Wales, Australia
| | - Annette T. Y. Wong
- Centre for Transplant and Renal Research, Westmead Institute for Medical Research, The University of Sydney, Sydney, New South Wales, Australia
- Department of Renal Medicine, Westmead Hospital, Western Sydney Local Health District, Sydney, New South Wales, Australia
| | - Gopala K. Rangan
- Centre for Transplant and Renal Research, Westmead Institute for Medical Research, The University of Sydney, Sydney, New South Wales, Australia
- Department of Renal Medicine, Westmead Hospital, Western Sydney Local Health District, Sydney, New South Wales, Australia
- * E-mail:
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Tawa M, Nagata R, Sumi Y, Nakagawa K, Sawano T, Ohkita M, Matsumura Y. Preventive effects of nitrate-rich beetroot juice supplementation on monocrotaline-induced pulmonary hypertension in rats. PLoS One 2021; 16:e0249816. [PMID: 33831045 PMCID: PMC8031446 DOI: 10.1371/journal.pone.0249816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 03/26/2021] [Indexed: 11/18/2022] Open
Abstract
Beetroot (Beta vulgaris L.) has a high level of nitrate; therefore, its dietary intake could increase nitric oxide (NO) level in the body, possibly preventing the development of pulmonary hypertension (PH). In this study, we examined the effects of beetroot juice (BJ) supplementation on PH and the contribution of nitrate to such effects using a rat model of monocrotaline (MCT, 60 mg/kg s.c.)-induced PH. Rats were injected subcutaneously with saline or 60 mg/kg MCT and were sacrificed 28 days after the injection. In some rats injected with MCT, BJ was supplemented from the day of MCT injection to the day of sacrifice. First, MCT-induced right ventricular systolic pressure elevation, pulmonary arterial medial thickening and muscularization, and right ventricular hypertrophy were suppressed by supplementation with low-dose BJ (nitrate: 1.3 mmol/L) but not high-dose BJ (nitrate: 4.3 mmol/L). Of the plasma nitrite, nitrate, and their sum (NOx) levels, only the nitrate levels were found to be increased by the high-dose BJ supplementation. Second, in order to clarify the possible involvement of nitrate in the preventive effects of BJ on PH symptoms, the effects of nitrate-rich BJ (nitrate: 0.9 mmol/L) supplementation were compared with those of the nitrate-depleted BJ. While the former exerted preventive effects on PH symptoms, such effects were not observed in rats supplemented with nitrate-depleted BJ. Neither supplementation with nitrate-rich nor nitrate-depleted BJ affected plasma nitrite, nitrate, and NOx levels. These findings suggest that a suitable amount of BJ ingestion, which does not affect systemic NO levels, can prevent the development of PH in a nitrate-dependent manner. Therefore, BJ could be highly useful as a therapy in patients with PH.
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Affiliation(s)
- Masashi Tawa
- Laboratory of Pathological and Molecular Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
- Department of Pharmacology, Kanazawa Medical University, Kahoku, Ishikawa, Japan
- * E-mail: ,
| | - Rikako Nagata
- Laboratory of Pathological and Molecular Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Yuiko Sumi
- Laboratory of Pathological and Molecular Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Keisuke Nakagawa
- Laboratory of Pathological and Molecular Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Tatsuya Sawano
- Laboratory of Pathological and Molecular Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
- Division of Molecular Pharmacology, Faculty of Medicine, Tottori University, Yonago, Tottori, Japan
| | - Mamoru Ohkita
- Laboratory of Pathological and Molecular Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Yasuo Matsumura
- Laboratory of Pathological and Molecular Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
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McCarty MF. Nutraceutical, Dietary, and Lifestyle Options for Prevention and Treatment of Ventricular Hypertrophy and Heart Failure. Int J Mol Sci 2021; 22:ijms22073321. [PMID: 33805039 PMCID: PMC8037104 DOI: 10.3390/ijms22073321] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/22/2021] [Accepted: 03/22/2021] [Indexed: 12/12/2022] Open
Abstract
Although well documented drug therapies are available for the management of ventricular hypertrophy (VH) and heart failure (HF), most patients nonetheless experience a downhill course, and further therapeutic measures are needed. Nutraceutical, dietary, and lifestyle measures may have particular merit in this regard, as they are currently available, relatively safe and inexpensive, and can lend themselves to primary prevention as well. A consideration of the pathogenic mechanisms underlying the VH/HF syndrome suggests that measures which control oxidative and endoplasmic reticulum (ER) stress, that support effective nitric oxide and hydrogen sulfide bioactivity, that prevent a reduction in cardiomyocyte pH, and that boost the production of protective hormones, such as fibroblast growth factor 21 (FGF21), while suppressing fibroblast growth factor 23 (FGF23) and marinobufagenin, may have utility for preventing and controlling this syndrome. Agents considered in this essay include phycocyanobilin, N-acetylcysteine, lipoic acid, ferulic acid, zinc, selenium, ubiquinol, astaxanthin, melatonin, tauroursodeoxycholic acid, berberine, citrulline, high-dose folate, cocoa flavanols, hawthorn extract, dietary nitrate, high-dose biotin, soy isoflavones, taurine, carnitine, magnesium orotate, EPA-rich fish oil, glycine, and copper. The potential advantages of whole-food plant-based diets, moderation in salt intake, avoidance of phosphate additives, and regular exercise training and sauna sessions are also discussed. There should be considerable scope for the development of functional foods and supplements which make it more convenient and affordable for patients to consume complementary combinations of the agents discussed here. Research Strategy: Key word searching of PubMed was employed to locate the research papers whose findings are cited in this essay.
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Affiliation(s)
- Mark F McCarty
- Catalytic Longevity Foundation, 811 B Nahant Ct., San Diego, CA 92109, USA
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9
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Kapil V, Khambata RS, Jones DA, Rathod K, Primus C, Massimo G, Fukuto JM, Ahluwalia A. The Noncanonical Pathway for In Vivo Nitric Oxide Generation: The Nitrate-Nitrite-Nitric Oxide Pathway. Pharmacol Rev 2020; 72:692-766. [DOI: 10.1124/pr.120.019240] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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10
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Peng R, Luo M, Tian R, Lu N. Dietary nitrate attenuated endothelial dysfunction and atherosclerosis in apolipoprotein E knockout mice fed a high-fat diet: A critical role for NADPH oxidase. Arch Biochem Biophys 2020; 689:108453. [PMID: 32524996 DOI: 10.1016/j.abb.2020.108453] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/01/2020] [Accepted: 06/02/2020] [Indexed: 02/06/2023]
Abstract
Nitric oxide (NO) deficiency and NADPH oxidase plays key roles in endothelial dysfunction and atherosclerotic plaque formation. Recent evidence demonstrates that nitrate-nitrite-NO pathway in vivo exerts beneficial effects upon the cardiovascular system. We aimed to investigate the effects of dietary nitrate on endothelial function and atherosclerosis in apolipoprotein E knockout (ApoE-/-) mice fed a high-fat diet. It was shown that dietary nitrate significantly attenuated aortic endothelial dysfunction and atherosclerosis in ApoE-/- mice. Mechanistic studies revealed that dietary nitrate significantly improved plasma nitrate/nitrite, inhibited vascular NADPH oxidase activity and oxidative stress in ApoE-/- mice, while xanthine oxidoreductase (XOR) expression and activity was enhanced in ApoE-/- mice in comparison with wide type animals. These beneficial effects of nitrate in ApoE-/- mice were abolished by PTIO (NO scavenger) and significantly prevented by febuxostat (XOR inhibitor). In the presence of nitrate, no further effect of apocynin (NADPH oxidase inhibitor) was observed, suggesting NADPH oxidase as a possible target. In vitro, NO donor significantly inhibited NADPH oxidase activity in vascular endothelial cells via the induction of heme oxygenase-1. Altogether, boosting this nitrate-nitrite-NO signaling pathway resulted in the decreases of vascular NADPH oxidase-derived oxidative stress and endothelial dysfunction, and consequently protected ApoE-/- mice against atherosclerosis. These findings may have novel nutritional implications for the preventive and therapeutic strategies against vascular endothelial dysfunction in atherosclerotic disease.
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Affiliation(s)
- Rou Peng
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, Key Laboratory of Green Chemistry, Jiangxi Province and College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, China
| | - Mengjuan Luo
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, Key Laboratory of Green Chemistry, Jiangxi Province and College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, China
| | - Rong Tian
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, Key Laboratory of Green Chemistry, Jiangxi Province and College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, China
| | - Naihao Lu
- Key Laboratory of Functional Small Organic Molecule, Ministry of Education, Key Laboratory of Green Chemistry, Jiangxi Province and College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, China.
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11
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Tawa M, Yano Y, Yamanaka M, Sawano T, Iesaki K, Murata Y, Tanaka R, Nakagawa K, Ohkita M, Matsumura Y. Effects of Beet Juice Supplementation on Monocrotaline-Induced Pulmonary Hypertension in Rats. Am J Hypertens 2019; 32:216-222. [PMID: 30265283 DOI: 10.1093/ajh/hpy144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 09/27/2018] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Recently, attention has been focused on the cardiovascular protective effects of beet juice (BJ) with high amounts of nitrate. In this study, we examined the effect of BJ supplementation in a rat model of monocrotaline (MCT)-induced pulmonary hypertension (PH). METHODS MCT (60 mg/kg) was subcutaneously administered to rats, and BJ (prepared by dissolving BJ powder at a concentration of 1 g/l or 10 g/l in drinking water) supplementation was started from the day of, 1 week before, and 2 weeks after MCT injection. Saline-injected rats given drinking water were used as controls. RESULTS Low-dose BJ supplementation starting from the day of MCT injection exerted protective effects on the MCT-induced elevation of right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary arterial remodeling, without causing a significant increase in plasma nitrite plus nitrate (NOx) levels. On the other hand, such beneficial effects were not observed with high-dose BJ supplementation, although the NOx levels were slightly higher than those in the low-dose group. In addition, low-dose BJ supplementation starting from 1 week before MCT injection did not improve PH symptoms, as described above. Furthermore, low-dose BJ supplementation starting from 2 weeks after MCT injection was ineffective against functional and morphological alterations in pulmonary circulation associated with MCT-induced PH. CONCLUSIONS Habitual ingestion of a suitable amount of BJ could be a potential option for preventing PH. However, beneficial effects cannot be expected when PH has developed to some degree.
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Affiliation(s)
- Masashi Tawa
- Department of Pharmacology, Kanazawa Medical University, Kahoku, Ishikawa, Japan
- Laboratory of Molecular and Pathological Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Yoko Yano
- Laboratory of Molecular and Pathological Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Misaki Yamanaka
- Laboratory of Molecular and Pathological Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Tatsuya Sawano
- Laboratory of Molecular and Pathological Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
- Division of Molecular Pharmacology, Faculty of Medicine, Tottori University, Yonago, Tottori, Japan
| | - Kana Iesaki
- Laboratory of Molecular and Pathological Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Yuka Murata
- Laboratory of Molecular and Pathological Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Ryosuke Tanaka
- Laboratory of Molecular and Pathological Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Keisuke Nakagawa
- Laboratory of Molecular and Pathological Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Mamoru Ohkita
- Laboratory of Molecular and Pathological Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
| | - Yasuo Matsumura
- Laboratory of Molecular and Pathological Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
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12
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Carlström M, Lundberg JO, Weitzberg E. Mechanisms underlying blood pressure reduction by dietary inorganic nitrate. Acta Physiol (Oxf) 2018; 224:e13080. [PMID: 29694703 DOI: 10.1111/apha.13080] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 03/28/2018] [Accepted: 04/18/2018] [Indexed: 12/20/2022]
Abstract
Nitric oxide (NO) importantly contributes to cardiovascular homeostasis by regulating blood flow and maintaining endothelial integrity. Conversely, reduced NO bioavailability is a central feature during natural ageing and in many cardiovascular disorders, including hypertension. The inorganic anions nitrate and nitrite are endogenously formed after oxidation of NO synthase (NOS)-derived NO and are also present in our daily diet. Knowledge accumulated over the past two decades has demonstrated that these anions can be recycled back to NO and other bioactive nitrogen oxides via serial reductions that involve oral commensal bacteria and various enzymatic systems. Intake of inorganic nitrate, which is predominantly found in green leafy vegetables and beets, has a variety of favourable cardiovascular effects. As hypertension is a major risk factor of morbidity and mortality worldwide, much attention has been paid to the blood pressure reducing effect of inorganic nitrate. Here, we describe how dietary nitrate, via stimulation of the nitrate-nitrite-NO pathway, affects various organ systems and discuss underlying mechanisms that may contribute to the observed blood pressure-lowering effect.
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Affiliation(s)
- M. Carlström
- Department of Physiology and Pharmacology; Karolinska Institutet; Stockholm Sweden
| | - J. O. Lundberg
- Department of Physiology and Pharmacology; Karolinska Institutet; Stockholm Sweden
| | - E. Weitzberg
- Department of Physiology and Pharmacology; Karolinska Institutet; Stockholm Sweden
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13
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Tan S, Caparros-Martin JA, Matthews VB, Koch H, O'Gara F, Croft KD, Ward NC. Isoquercetin and inulin synergistically modulate the gut microbiome to prevent development of the metabolic syndrome in mice fed a high fat diet. Sci Rep 2018; 8:10100. [PMID: 29973701 PMCID: PMC6031638 DOI: 10.1038/s41598-018-28521-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/20/2018] [Indexed: 12/17/2022] Open
Abstract
Dietary fibre positively influences gut microbiome composition, enhancing the metabolism of dietary flavonoids to produce bioactive metabolites. These synergistic activities facilitate the beneficial effects of dietary flavonoids on cardiometabolic health parameters. The aims of this study were to investigate whether isoquercetin (a major dietary flavonoid) and inulin (soluble fibre), either alone or in combination could improve features of the metabolic syndrome. Following a 1 week acclimatization, male C57BL6 mice (6–8 weeks) were randomly assigned to; (i) normal chow diet (n = 10), (ii) high fat (HF) diet (n = 10), (iii) HF diet + 0.05% isoquercetin (n = 10), (iv) HF diet + 5% inulin, or (v) HF diet + 0.05% isoquercetin + 5% inulin (n = 10). Body weight and food intake were measured weekly. At 12 weeks, glucose and insulin tolerance tests were performed, and blood, faecal samples, liver, skeletal muscle and adipose tissue were collected. At 12 weeks, mice on the HF diet had significantly elevated body weights as well as impaired glucose tolerance and insulin sensitivity compared to the normal chow mice. Supplementation with either isoquercetin or inulin had no effect, however mice receiving the combination had attenuated weight gain, improved glucose tolerance and insulin sensitivity, reduced hepatic lipid accumulation, adipocyte hypertrophy, circulating leptin and adipose FGF21 levels, compared to mice receiving the HF diet. Additionally, mice on the combination diet had improvements in the composition and functionality of their gut microbiome as well as production of short chain fatty acids. In conclusion, long-term supplementation with the dietary flavonoid isoquercetin and the soluble fibre inulin can attenuate development of the metabolic syndrome in mice fed a high fat diet. This protective effect appears to be mediated, in part, through beneficial changes to the microbiome.
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Affiliation(s)
- Si Tan
- Life Science and Technology Institute, Yangtze Normal University, Chongqing, China.,School of Biomedical Sciences, University of Western Australia, Perth, Australia
| | - Jose A Caparros-Martin
- School of Biomedical Sciences & Curtin Health Innovation Research Institute, Curtin University, Perth, Australia
| | - Vance B Matthews
- School of Biomedical Sciences, University of Western Australia, Perth, Australia
| | - Henrietta Koch
- School of Biomedical Sciences, University of Western Australia, Perth, Australia
| | - Fergal O'Gara
- School of Biomedical Sciences & Curtin Health Innovation Research Institute, Curtin University, Perth, Australia.,Biomerit Research Centre, School of Microbiology, National University of Ireland, Cork, Ireland
| | - Kevin D Croft
- School of Biomedical Sciences, University of Western Australia, Perth, Australia
| | - Natalie C Ward
- School of Biomedical Sciences & Curtin Health Innovation Research Institute, Curtin University, Perth, Australia. .,Medical School, University of Western Australia, Perth, Australia.
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14
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Blekkenhorst LC, Bondonno NP, Liu AH, Ward NC, Prince RL, Lewis JR, Devine A, Croft KD, Hodgson JM, Bondonno CP. Nitrate, the oral microbiome, and cardiovascular health: a systematic literature review of human and animal studies. Am J Clin Nutr 2018; 107:504-522. [PMID: 29635489 DOI: 10.1093/ajcn/nqx046] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/21/2017] [Indexed: 12/25/2022] Open
Abstract
Background Dietary nitrate is an important source of nitric oxide (NO), a molecule critical for cardiovascular health. Nitrate is sequentially reduced to NO through an enterosalivary nitrate-nitrite-NO pathway that involves the oral microbiome. This pathway is considered an important adjunct pathway to the classical l-arginine-NO synthase pathway. Objective The objective of this study was to systematically assess the evidence for dietary nitrate intake and improved cardiovascular health from both human and animal studies. Design A systematic literature search was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines by using key search terms in Medline and EMBASE databases and defined inclusion and exclusion criteria. Results Thirty-seven articles on humans and 14 articles on animals were included from 12,541 screened references. Data on the effects of dietary nitrate on blood pressure, endothelial function, ischemic reperfusion injury, arterial stiffness, platelet function, and cerebral blood flow in both human and animal models were identified. Beneficial effects of nitrate on vascular health have predominantly been observed in healthy human populations, whereas effects in populations at risk of cardiovascular disease are less clear. Few studies have investigated the long-term effects of dietary nitrate on cardiovascular disease clinical endpoints. In animal studies, there is evidence that nitrate improves blood pressure and endothelial function, particularly in animal models with reduced NO bioavailability. Nitrate dose seems to be a critical factor because there is evidence of cross-talk between the 2 pathways of NO production. Conclusions Evidence for a beneficial effect in humans at risk of cardiovascular disease is limited. Furthermore, there is a need to investigate the long-term effects of dietary nitrate on cardiovascular disease clinical endpoints. Further animal studies are required to elucidate the mechanisms behind the observed effects.
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Affiliation(s)
- Lauren C Blekkenhorst
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia.,School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Nicola P Bondonno
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia
| | - Alex H Liu
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia
| | - Natalie C Ward
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia.,School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia
| | - Richard L Prince
- Medical School, Queen Elizabeth Medical Center Unit, University of Western Australia, Nedlands, Western Australia, Australia
| | - Joshua R Lewis
- Medical School, Queen Elizabeth Medical Center Unit, University of Western Australia, Nedlands, Western Australia, Australia
| | - Amanda Devine
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Kevin D Croft
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia
| | - Jonathan M Hodgson
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia.,School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Catherine P Bondonno
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia.,School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
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15
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Matthews VB, Hollingshead R, Koch H, Croft KD, Ward NC. Long-Term Dietary Nitrate Supplementation Does Not Prevent Development of the Metabolic Syndrome in Mice Fed a High-Fat Diet. Int J Endocrinol 2018; 2018:7969750. [PMID: 30174691 PMCID: PMC6098922 DOI: 10.1155/2018/7969750] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 07/19/2018] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Nitric oxide (NO) is an important vascular signaling molecule that plays a role in vascular homeostasis. A reduction in NO bioavailability is thought to contribute to endothelial dysfunction, an early risk factor for both cardiovascular disease and type 2 diabetes. Dietary nitrate, through the nitrate-nitrite-NO pathway, may provide an alternate source of NO when the endogenous eNOS system is compromised. In addition to a role in the vascular system, NO may also play a role in the metabolic syndrome including obesity and glucose tolerance. AIM To investigate the effect of long-term dietary nitrate supplementation on development of the metabolic syndrome in mice fed a high-fat diet. METHODS Following 1 week of acclimatisation, male (6-8 weeks) C57BL6 mice were randomly assigned to the following groups (10/group) for 12 weeks: (i) normal chow + NaCl (1 mmol/kg/day), (ii) normal chow + NaNO3 (1 mmol/kg/day), (iii) high-fat diet + NaCl (1 mmol/kg/day), and (iv) high-fat diet + NaNO3 (1 mmol/kg/day). Body weight and food consumption were monitored weekly. A subset of mice (5/group) underwent running wheel assessment. At the end of the treatment period, all mice underwent fasting glucose tolerance testing. Caecum contents, serum, and tissues (liver, skeletal muscle, white and brown adipose, and kidney) were collected, frozen, and stored at -80°C until analysis. RESULTS Consumption of the high-fat diet resulted in significantly greater weight gain that was not affected by dietary nitrate. Mice on the high-fat diet also had impaired glucose tolerance that was not affected by dietary nitrate. There was no difference in adipose tissue expression of thermogenic proteins or energy expenditure as assessed by the running wheel activity. Mice on the high-fat diet and those receiving dietary nitrate had reduced caecum concentrations of both butyrate and propionate. CONCLUSIONS Dietary nitrate does not prevent development of the metabolic syndrome in mice fed a high-fat diet. This may be due, in part due, to reductions in the concentration of important short-chain fatty acids.
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Affiliation(s)
- V. B. Matthews
- School of Biomedical Sciences, The University of Western Australia, Perth, WA, Australia
| | - R. Hollingshead
- School of Biomedical Sciences & Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
| | - H. Koch
- School of Biomedical Sciences, The University of Western Australia, Perth, WA, Australia
| | - K. D. Croft
- School of Biomedical Sciences, The University of Western Australia, Perth, WA, Australia
| | - N. C. Ward
- School of Biomedical Sciences & Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
- Medical School, The University of Western Australia, Perth, WA, Australia
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