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Latva-Rasku A, Rebelos E, Tuisku J, Aarnio R, Bhowmik A, Keskinen H, Laurila S, Lahesmaa-Hatting M, Pekkarinen L, Isackson H, Kirjavainen AK, Koffert J, Heurling K, Nummenmaa L, Ferrannini E, Oldgren J, Oscarsson J, Nuutila P. SGLT2 Inhibitor Dapagliflozin Increases Skeletal Muscle and Brain Fatty Acid Uptake in Individuals With Type 2 Diabetes: A Randomized Double-Blind Placebo-Controlled Positron Emission Tomography Study. Diabetes Care 2024; 47:1630-1637. [PMID: 38941156 DOI: 10.2337/dc24-0470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 06/10/2024] [Indexed: 06/30/2024]
Abstract
OBJECTIVE The aim of this study was to investigate the impact of the sodium-glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin on tissue fatty acid (FA) uptake in the skeletal muscle, brain, small intestine, and subcutaneous and visceral adipose tissue of individuals with type 2 diabetes by using positron emission tomography (PET). RESEARCH DESIGN AND METHODS In a 6-week randomized double-blind placebo-controlled trial, 53 patients with type 2 diabetes treated with metformin received either 10 mg dapagliflozin or placebo daily. Tissue FA uptake was quantified at baseline and end of treatment with PET and the long-chain FA analog radiotracer 14(R,S)-[18F]fluoro-6-thia-heptadecanoic acid. Treatment effects were assessed using ANCOVA, and the results are reported as least square means and 95% CIs for the difference between groups. RESULTS A total of 38 patients (dapagliflozin n = 21; placebo n = 17) completed the study. After 6 weeks, skeletal muscle FA uptake was increased by dapagliflozin compared with placebo (1.0 [0.07, 2.0] μmol ⋅ 100 g-1 ⋅ min-1; P = 0.032), whereas uptake was not significantly changed in the small intestine or visceral or subcutaneous adipose tissue. Dapagliflozin treatment significantly increased whole-brain FA uptake (0.10 [0.02, 0.17] μmol ⋅ 100 g-1 ⋅ min-1; P = 0.01), an effect observed in both gray and white matter regions. CONCLUSIONS Six weeks of treatment with dapagliflozin increases skeletal muscle and brain FA uptake, partly driven by a rise in free FA availability. This finding is in accordance with previous indirect measurements showing enhanced FA metabolism in response to SGLT2 inhibition and extends the notion of a shift toward increased FA use to muscle and brain.
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Affiliation(s)
- Aino Latva-Rasku
- Turku PET Centre, University of Turku, Turku, Finland
- Department of Endocrinology, Turku University Hospital, Turku, Finland
| | - Eleni Rebelos
- Turku PET Centre, University of Turku, Turku, Finland
| | - Jouni Tuisku
- Turku PET Centre, University of Turku, Turku, Finland
| | | | - Achol Bhowmik
- Turku PET Centre, University of Turku, Turku, Finland
| | | | - Sanna Laurila
- Turku PET Centre, University of Turku, Turku, Finland
- Heart Center, Turku University Hospital, Turku, Finland
| | | | - Laura Pekkarinen
- Turku PET Centre, University of Turku, Turku, Finland
- Department of Endocrinology, Turku University Hospital, Turku, Finland
| | - Henrik Isackson
- Clinical Physiology and Cardiology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
- Integrative Physiology, Medical Cell Biology, Uppsala University Hospital, Uppsala, Sweden
| | - Anna K Kirjavainen
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland
| | - Jukka Koffert
- Turku PET Centre, University of Turku, Turku, Finland
| | | | - Lauri Nummenmaa
- Turku PET Centre, University of Turku, Turku, Finland
- Department of Psychology, University of Turku, Turku, Finland
| | - Ele Ferrannini
- National Research Council Institute of Clinical Physiology, Pisa, Italy
| | - Jonas Oldgren
- Clinical Physiology and Cardiology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
- Uppsala Clinical Research Center, Uppsala University, Uppsala, Sweden
| | - Jan Oscarsson
- Late-Stage Development, Cardiovascular, Renal, and Metabolism, BioPharmaceuticals Research and Development, AstraZeneca, Gothenburg, Sweden
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku, Turku, Finland
- Department of Endocrinology, Turku University Hospital, Turku, Finland
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Aarnio R, Kirjavainen A, Rajander J, Forsback S, Kalliokoski K, Nuutila P, Milicevic Z, Coskun T, Haupt A, Laitinen I, Haaparanta-Solin M. New improved radiometabolite analysis method for [ 18F]FTHA from human plasma: a test-retest study with postprandial and fasting state. EJNMMI Res 2024; 14:53. [PMID: 38869780 DOI: 10.1186/s13550-024-01114-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Accepted: 05/28/2024] [Indexed: 06/14/2024] Open
Abstract
BACKGROUND Fatty acid uptake can be measured using PET and 14-(R,S)-[18F]fluoro-6-thia-heptadecanoic acid ([18F]FTHA). However, the relatively rapid rate of [18F]FTHA metabolism significantly affects kinetic modeling of tissue uptake. Thus, there is a need for accurate chromatographic methods to analyze the unmetabolized [18F]FTHA (parent fraction). Here we present a new radiometabolite analysis (RMA) method, with comparison to a previous method for parent fraction analysis, and its use in a test-retest clinical study under fasting and postprandial conditions. We developed a new thin-layer chromatography (TLC) RMA method for analysis of [18F]FTHA parent fraction and its radiometabolites from plasma, by testing stationary phases and eluent combinations. Next, we analyzed [18F]FTHA, its radiometabolites, and plasma radioactivity from subjects participating in a clinical study. A total of 17 obese or overweight participants were dosed with [18F]FTHA twice under fasting, and twice under postprandial conditions and plasma samples were obtained between 14 min (mean of first sample) and 72 min (mean of last sample) post-injection. Aliquots of 70 plasma samples were analyzed using both methods, enabling head-to-head comparisons. We performed test-retest and group comparisons of the parent fraction and plasma radioactivity. RESULTS The new TLC method separated seven [18F]FTHA radiometabolite peaks, while the previous method separated three. The new method revealed at least one radiometabolite that was not previously separable from [18F]FTHA. From the plasma samples, the mean parent fraction value was on average 7.2 percentage points lower with the new method, compared to the previous method. Repeated [18F]FTHA investigations on the same subject revealed reproducible plasma SUV and parent fractions, with different kinetics between the fasted and postprandial conditions. CONCLUSIONS The newly developed improved radio-TLC method for [18F]FTHA RMA enables accurate parent fraction correction, which is required to obtain quantitative data for modelling [18F]FTHA PET data. Our test-retest study of fasted and postprandial conditions showed robust reproducibility, and revealed clear differences in the [18F]FTHA metabolic rate under different study settings. TRIAL REGISTRATION EudraCT No: 2020-005211-48, 04Feb2021; and Clinical Trials registry NCT05132335, 29Oct2021, URL: https://classic. CLINICALTRIALS gov/ct2/show/NCT05132335 .
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Affiliation(s)
- Richard Aarnio
- MediCity Research Laboratory, University of Turku, Turku, Finland.
- Drug Research Doctoral Programme, University of Turku, Turku, Finland.
- Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, Turku, FI-20520, Finland.
| | - Anna Kirjavainen
- Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, Turku, FI-20520, Finland
| | - Johan Rajander
- Accelerator Laboratory, Turku PET Centre, Åbo Akademi University, Turku, Finland
| | - Sarita Forsback
- Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, Turku, FI-20520, Finland
| | - Kari Kalliokoski
- Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, Turku, FI-20520, Finland
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, Turku, FI-20520, Finland
- Department of Endocrinology, Turku University Hospital, Turku, Finland
| | | | | | - Axel Haupt
- Eli Lilly and Company, Indianapolis, IN, USA
| | | | - Merja Haaparanta-Solin
- MediCity Research Laboratory, University of Turku, Turku, Finland
- Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, Turku, FI-20520, Finland
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Katsanos CS, Tran L, Hoffman N, Roust LR, De Filippis EA, Mandarino LJ, Johnsson K, Belohlavek M, Buras MR. Impaired Suppression of Plasma Lipid Extraction and its Partitioning Away from Muscle by Insulin in Humans with Obesity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.11.598550. [PMID: 38915696 PMCID: PMC11195248 DOI: 10.1101/2024.06.11.598550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Context Humans with obesity and insulin resistance exhibit lipid accumulation in skeletal muscle, but the underlying biological mechanisms responsible for the accumulation of lipid in the muscle of these individuals remain unknown. Objective We investigated how plasma insulin modulates the extraction of circulating triglycerides (TGs) and non-esterified fatty acids (NEFAs) from dietary and endogenous sources in the muscle of lean, insulin-sensitive humans (Lean-IS) and contrasted these responses to those in humans with obesity and insulin resistance (Obese-IR). Methods The studies were performed in a postprandial state associated with steady-state plasma TG concentrations. The arterio-venous blood sampling technique was employed to determine the extraction of circulating lipids across the forearm muscle before and after insulin infusion. We distinguished kinetics of TGs and NEFAs from dietary sources across muscle from those from endogenous sources by incorporating stable isotope-labeled triolein in ingested fat. Results Plasma insulin rapidly suppressed the extraction of plasma TGs from endogenous, but not dietary, sources in the Lean-IS, but same response was absent in the Obese-IR. Furthermore, in the muscle of Lean-IS, plasma insulin decreased the extraction of circulating NEFAs from both dietary and endogenous sources, but in Obese-IR subjects this response was absent for NEFAs from dietary sources. Conclusions Partitioning of circulating lipids away from the skeletal muscle when plasma insulin increases, such as during the postprandial period, is impaired in humans with obesity and insulin resistance. Trial Registration: ClinicalTrials.gov ( NCT01860911 ).
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High-fructose feeding suppresses cold-stimulated brown adipose tissue glucose uptake independently of changes in thermogenesis and the gut microbiome. Cell Rep Med 2022; 3:100742. [PMID: 36130480 PMCID: PMC9512695 DOI: 10.1016/j.xcrm.2022.100742] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 06/14/2022] [Accepted: 08/23/2022] [Indexed: 12/30/2022]
Abstract
Diets rich in added sugars are associated with metabolic diseases, and studies have shown a link between these pathologies and changes in the microbiome. Given the reported associations in animal models between the microbiome and brown adipose tissue (BAT) function, and the alterations in the microbiome induced by high-glucose or high-fructose diets, we investigated the potential causal link between high-glucose or -fructose diets and BAT dysfunction in humans. Primary outcomes are changes in BAT cold-induced thermogenesis and the fecal microbiome (clinicaltrials.gov, NCT03188835). We show that BAT glucose uptake, but not thermogenesis, is impaired by a high-fructose but not high-glucose diet, in the absence of changes in the gastrointestinal microbiome. We conclude that decreased BAT glucose metabolism occurs earlier than other pathophysiological abnormalities during fructose overconsumption in humans. This is a potential confounding factor for studies relying on 18F-FDG to assess BAT thermogenesis. Fructose overfeeding decreases brown adipose tissue glucose metabolism These changes occur independently of oxidative metabolism No change is observed with glucose overfeeding The gut microbiome is not affected by fructose/glucose overfeeding
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Löffler MC, Betz MJ, Blondin DP, Augustin R, Sharma AK, Tseng YH, Scheele C, Zimdahl H, Mark M, Hennige AM, Wolfrum C, Langhans W, Hamilton BS, Neubauer H. Challenges in tackling energy expenditure as obesity therapy: From preclinical models to clinical application. Mol Metab 2021; 51:101237. [PMID: 33878401 PMCID: PMC8122111 DOI: 10.1016/j.molmet.2021.101237] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/31/2021] [Accepted: 04/13/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND A chronic imbalance of energy intake and energy expenditure results in excess fat storage. The obesity often caused by this overweight is detrimental to the health of millions of people. Understanding both sides of the energy balance equation and their counter-regulatory mechanisms is critical to the development of effective therapies to treat this epidemic. SCOPE OF REVIEW Behaviors surrounding ingestion have been reviewed extensively. This review focuses more specifically on energy expenditure regarding bodyweight control, with a particular emphasis on the organs and attractive metabolic processes known to reduce bodyweight. Moreover, previous and current attempts at anti-obesity strategies focusing on energy expenditure are highlighted. Precise measurements of energy expenditure, which consist of cellular, animal, and human models, as well as measurements of their translatability, are required to provide the most effective therapies. MAJOR CONCLUSIONS A precise understanding of the components surrounding energy expenditure, including tailored approaches based on genetic, biomarker, or physical characteristics, must be integrated into future anti-obesity treatments. Further comprehensive investigations are required to define suitable treatments, especially because the complex nature of the human perspective remains poorly understood.
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Affiliation(s)
- Mona C Löffler
- Cardio Metabolic Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, Biberach, Germany
| | - Matthias J Betz
- Department of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland
| | - Denis P Blondin
- Department of Medicine, Division of Neurology, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, QC, Canada
| | - Robert Augustin
- Cardio Metabolic Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, Biberach, Germany
| | - Anand K Sharma
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland
| | - Yu-Hua Tseng
- Joslin Diabetes Center, Section on Integrative Physiology and Metabolism, Harvard Medical School, Boston, MA, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA
| | - Camilla Scheele
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Denmark
| | - Heike Zimdahl
- Cardio Metabolic Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, Biberach, Germany
| | - Michael Mark
- Cardio Metabolic Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, Biberach, Germany
| | - Anita M Hennige
- Therapeutic Area CardioMetabolism & Respiratory, Boehringer Ingelheim International GmbH, Biberach, Germany
| | - Christian Wolfrum
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland
| | - Wolfgang Langhans
- Physiology and Behavior Laboratory, Department of Health Sciences and Technology, ETH Zürich, Switzerland
| | - Bradford S Hamilton
- Cardio Metabolic Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, Biberach, Germany
| | - Heike Neubauer
- Cardio Metabolic Diseases Research, Boehringer Ingelheim Pharma GmbH & Co KG, Biberach, Germany.
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Du Y, Taylor CG, Aukema HM, Zahradka P. Regulation of docosahexaenoic acid-induced apoptosis of confluent endothelial cells: Contributions of MAPKs and caspases. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158902. [PMID: 33578050 DOI: 10.1016/j.bbalip.2021.158902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 12/20/2020] [Accepted: 02/06/2021] [Indexed: 12/11/2022]
Abstract
Endothelial cells, which help to maintain vascular homeostasis, can be functionally modulated by polyunsaturated fatty acids. Previously, we reported that docosahexaenoic acid (DHA) reduced the viability of confluent EA.hy926 endothelial cells with caspase-3 activation. This study therefore examined the molecular mechanism by which DHA affects the viability of confluent cells, with a focus on the interaction between caspase-9, caspase-8, caspase-3, p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) by Western blotting. Our results revealed that DHA induces apoptosis of confluent cells through both intrinsic and extrinsic pathways, which requires activation of p38 MAPK, and involves activation of JNK, caspase-9, caspase-8 and caspase-3 with the exception that cleavage of caspase-8 was incomplete and truncated BID was not detected at the maximum time (8 h) examined. Apoptosis induced by high levels of DHA in healthy endothelial cells is achieved through positive feedback loops linking these MAPKs to multiple caspases, as well as negative feedback from p38 MAPK to JNK. However, only p38 MAPK is crucial in apoptosis induction in comparison with JNK or any other caspase examined. This study has expanded the knowledge on the molecular mechanism of DHA-induced apoptosis in human endothelial cells and has also implied the differential roles of MAP kinases and caspases in apoptosis.
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Affiliation(s)
- Youjia Du
- Department of Physiology & Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Manitoba, Canada
| | - Carla G Taylor
- Department of Physiology & Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada; Department of Food and Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Manitoba, Canada
| | - Harold M Aukema
- Department of Food and Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Manitoba, Canada
| | - Peter Zahradka
- Department of Physiology & Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada; Department of Food and Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Manitoba, Canada.
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Noll C, Montastier É, Amrani M, Kunach M, Frisch F, Fortin M, Bouffard L, Dubreuil S, Phoenix S, Cunnane SC, Guérin B, Turcotte EE, Laville M, Carpentier AC. Seven-day overfeeding enhances adipose tissue dietary fatty acid storage and decreases myocardial and skeletal muscle dietary fatty acid partitioning in healthy subjects. Am J Physiol Endocrinol Metab 2020; 318:E286-E296. [PMID: 31891539 DOI: 10.1152/ajpendo.00474.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Increased myocardial partitioning of dietary fatty acids (DFA) and decreased left ventricular (LV) function is associated with insulin resistance in prediabetes. We hypothesized that enhanced myocardial DFA partitioning and reduced LV function might be induced concomitantly with reduced insulin sensitivity upon a 7-day hypercaloric (+50% in caloric intake), high-saturated fat (~11%energy), and simple carbohydrates (~54%energy) diet (HIGHCAL) versus an isocaloric diet (ISOCAL) with a moderate amount of saturated fat (~8%energy) and carbohydrates (~50%energy). Thirteen healthy subjects (7 men/6 women) underwent HIGHCAL versus ISOCAL in a randomized crossover design, with organ-specific DFA partitioning and LV function measured using the oral 14(R,S)-[18F]fluoro-6-thia-heptadecanoic acid and [11C]acetate positron emission tomography methods at the end of both interventions. HIGHCAL induced a decrease in insulin sensitivity indexes with no significant change in body composition. HIGHCAL led to increased subcutaneous abdominal (+4.2 ± 1.6%, P < 0.04) and thigh (+2.4 ± 1.2%, P < 0.08) adipose tissue storage and reduced cardiac (-0.31 ± 0.11 mean standard uptake value [(SUV), P < 0.03] and skeletal muscle (-0.17 ± 0.08 SUV, P < 0.05) DFA partitioning without change in LV function. We conclude that early increase in adipose tissue DFA storage protects the heart and skeletal muscles from potential deleterious effects of DFA.
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Affiliation(s)
- Christophe Noll
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Émilie Montastier
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Mehdi Amrani
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Margaret Kunach
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Frédérique Frisch
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Mélanie Fortin
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Lucie Bouffard
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Stéphanie Dubreuil
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Serge Phoenix
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Stephen C Cunnane
- Research Center on Aging, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Brigitte Guérin
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Eric E Turcotte
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Martine Laville
- Department of Endocrinology, Diabetology and Nutrition, Groupement Hospitalier Lyon Sud, Fédération Hospitalo-Universitaire DO-IT, Hospices Civils de Lyon, Pierre Bénite, France
| | - André C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Labbé SM, Caron A, Festuccia WT, Lecomte R, Richard D. Interscapular brown adipose tissue denervation does not promote the oxidative activity of inguinal white adipose tissue in male mice. Am J Physiol Endocrinol Metab 2018; 315:E815-E824. [PMID: 30153064 DOI: 10.1152/ajpendo.00210.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Brown adipose tissue (BAT) thermogenesis is a key controller of energy metabolism. In response to cold or other adrenergic stimuli, brown adipocytes increase their substrate uptake and oxidative activity while uncoupling ATP synthesis from the mitochondrial respiratory chain activity. Brown adipocytes are found in classic depots such as in the interscapular BAT (iBAT). They can also develop in white adipose tissue (WAT), such as in the inguinal WAT (iWAT), where their presence has been associated with metabolic improvements. We previously reported that the induction of oxidative metabolism in iWAT is low compared with that of iBAT, even after sustained adrenergic stimulation. One explanation to this apparent lack of thermogenic ability of iWAT is the presence of an active iBAT, which may prevent the full activation of iWAT. In this study, we evaluated whether iBAT denervation-induced browning of white fat enhanced the thermogenic activity of iWAT following cold acclimation, under beta-3 adrenergic stimulation (CL 316,243). Following a bilateral denervation of iBAT, we assessed energy balance, evaluated the oxidative activity of iBAT and iWAT using 11C-acetate, and quantified the dynamic glucose uptake of those tissues using 2-deoxy-2-[18F]- fluoro-d-glucose. Our results indicate that despite portraying marked browning and mildly enhanced glucose uptake, iWAT of cold-adapted mice does not exhibit significant oxidative activity following beta-3 adrenergic stimulation in the absence of a functional iBAT. The present results suggest that iWAT is not readily recruitable as a thermogenic organ even when functional iBAT is lacking.
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Affiliation(s)
- Sébastien M Labbé
- Institut universitaire de Cardiologie et de Pneumologie de Québec , Quebec, Quebec , Canada
- Département de Médecine, Faculté de Médecine, Université Laval , Québec, Québec , Canada
| | - Alexandre Caron
- Institut universitaire de Cardiologie et de Pneumologie de Québec , Quebec, Quebec , Canada
- Département de Médecine, Faculté de Médecine, Université Laval , Québec, Québec , Canada
| | - William T Festuccia
- Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of São Paulo , São Paulo , Brazil
| | - Roger Lecomte
- Département de Médecine nucléaire et de Radiologie, Centre d'Imagerie moléculaire de Sherbrooke, Université de Sherbrooke , Sherbrooke , Canada
| | - Denis Richard
- Institut universitaire de Cardiologie et de Pneumologie de Québec , Quebec, Quebec , Canada
- Département de Médecine, Faculté de Médecine, Université Laval , Québec, Québec , Canada
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Trouwborst I, Bowser SM, Goossens GH, Blaak EE. Ectopic Fat Accumulation in Distinct Insulin Resistant Phenotypes; Targets for Personalized Nutritional Interventions. Front Nutr 2018; 5:77. [PMID: 30234122 PMCID: PMC6131567 DOI: 10.3389/fnut.2018.00077] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 08/15/2018] [Indexed: 12/13/2022] Open
Abstract
Cardiometabolic diseases are one of the leading causes for disability and mortality in the Western world. The prevalence of these chronic diseases is expected to rise even further in the next decades. Insulin resistance (IR) and related metabolic disturbances are linked to ectopic fat deposition, which is the storage of excess lipids in metabolic organs such as liver and muscle. Notably, a vicious circle exists between IR and ectopic fat, together increasing the risk for the development of cardiometabolic diseases. Nutrition is a key-determining factor for both IR and ectopic fat deposition. The macronutrient composition of the diet may impact metabolic processes related to ectopic fat accumulation and IR. Interestingly, however, the metabolic phenotype of an individual may determine the response to a certain diet. Therefore, population-based nutritional interventions may not always lead to the most optimal (cardiometabolic) outcomes at the individual level, and differences in the metabolic phenotype may underlie conflicting findings related to IR and ectopic fat in dietary intervention studies. Detailed metabolic phenotyping will help to better understand the complex relationship between diet and metabolic regulation, and to optimize intervention outcomes. A subgroup-based approach that integrates, among others, tissue-specific IR, cardiometabolic parameters, anthropometrics, gut microbiota, age, sex, ethnicity, and psychological factors may thereby increase the efficacy of dietary interventions. Nevertheless, the implementation of more personalized nutrition may be complex, costly, and time consuming. Future studies are urgently warranted to obtain insight into a more personalized approach to nutritional interventions, taking into account the metabolic phenotype to ultimately improve insulin sensitivity and reduce the risk for cardiometabolic diseases.
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Affiliation(s)
- Inez Trouwborst
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, Netherlands
| | - Suzanne M Bowser
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, Netherlands
| | - Gijs H Goossens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, Netherlands
| | - Ellen E Blaak
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, Netherlands
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10
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Carpentier AC, Blondin DP, Virtanen KA, Richard D, Haman F, Turcotte ÉE. Brown Adipose Tissue Energy Metabolism in Humans. Front Endocrinol (Lausanne) 2018; 9:447. [PMID: 30131768 PMCID: PMC6090055 DOI: 10.3389/fendo.2018.00447] [Citation(s) in RCA: 197] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 07/20/2018] [Indexed: 12/16/2022] Open
Abstract
The demonstration of metabolically active brown adipose tissue (BAT) in humans primarily using positron emission tomography coupled to computed tomography (PET/CT) with the glucose tracer 18-fluorodeoxyglucose (18FDG) has renewed the interest of the scientific and medical community in the possible role of BAT as a target for the prevention and treatment of obesity and type 2 diabetes (T2D). Here, we offer a comprehensive review of BAT energy metabolism in humans. Considerable advances in methods to measure BAT energy metabolism, including nonesterified fatty acids (NEFA), chylomicron-triglycerides (TG), oxygen, Krebs cycle rate, and intracellular TG have led to very good quantification of energy substrate metabolism per volume of active BAT in vivo. These studies have also shown that intracellular TG are likely the primary energy source of BAT upon activation by cold. Current estimates of BAT's contribution to energy expenditure range at the lower end of what would be potentially clinically relevant if chronically sustained. Yet, 18FDG PET/CT remains the gold-standard defining method to quantify total BAT volume of activity, used to calculate BAT's total energy expenditure. Unfortunately, BAT glucose metabolism better reflects BAT's insulin sensitivity and blood flow. It is now clear that most glucose taken up by BAT does not fuel mitochondrial oxidative metabolism and that BAT glucose uptake can therefore be disconnected from thermogenesis. Furthermore, BAT thermogenesis is efficiently recruited upon repeated cold exposure, doubling to tripling its total oxidative capacity, with reciprocal reduction of muscle thermogenesis. Recent data suggest that total BAT volume may be much larger than the typically observed 50-150 ml with 18FDG PET/CT. Therefore, the current estimates of total BAT thermogenesis, largely relying on total BAT volume using 18FDG PET/CT, may underestimate the true contribution of BAT to total energy expenditure. Quantification of the contribution of BAT to energy expenditure begs for the development of more integrated whole body in vivo methods.
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Affiliation(s)
- André C. Carpentier
- Division of Endocrinology, Department of Medicine, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, QC, Canada
| | | | - Kirsi A. Virtanen
- Turku PET Centre, Turku University Hospital, Turku, Finland
- Institute of Public Health and Clinical Nutrition, University of Eastern Finland (UEF), Kuopio, Finland
| | - Denis Richard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, QC, Canada
| | - François Haman
- Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Éric E. Turcotte
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, QC, Canada
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11
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Importance of extracellular matrix and growth state for the EA.hy926 endothelial cell response to polyunsaturated fatty acids. PLoS One 2018; 13:e0197613. [PMID: 29763471 PMCID: PMC5953484 DOI: 10.1371/journal.pone.0197613] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 05/04/2018] [Indexed: 12/31/2022] Open
Abstract
Consumption of different PUFAs (polyunsaturated fatty acids) can induce functional changes in blood vessels via endothelial cells, which interact with dietary factors in the circulation. The basement membrane that separates the endothelium from the smooth muscle cells of the medial layer can also influence the functional state of endothelial cells. However, the effect of basement membrane on the endothelial response to dietary PUFAs in relation to growth state (e.g. proliferation versus quiescence) has never been investigated. We therefore compared the viability (CCK kit) and proliferation (bromodeoxyuridine incorporation) of EA.hy926 endothelial cells grown on Matrigel or collagen versus non-coated plates. EA.hy926 viability and proliferation were also assessed after treatment with 0–150 μM of PUFAs [linoleic acid (LA), arachidonic acid (AA), α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)]. Our study showed that only cells grown on Matrigel-coated plates reached quiescence after becoming confluent with a decreased level of MCM2 and p-cyclin D1 (T286), increased levels of p27kip1 and a low level of apoptosis and senescence. AA, EPA and DHA decreased the viability and proliferation of subconfluent cells grown on plastic dishes in a dose-dependent manner, while the presence of Matrigel made the cells resistant to these adverse effects. Confluent cell viability was less sensitive to higher concentrations of AA, EPA and DHA than subconfluent cells, and a significant increase in caspase-3 cleavage was only observed in confluent cells treated with DHA. Higher concentrations of AA, EPA and DHA suppressed DNA synthesis by both subconfluent and confluent cells, while precursor C18 PUFAs (LA and ALA) had no negative effects on viability and proliferation. Our study is the first to show that extracellular matrix and growth state are important factors in the EA.hy926 cell response to PUFAs, and that the mechanisms by which individual PUFAs operate may be growth state-dependent.
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12
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Li H, Xiao Y, Tang L, Zhong F, Huang G, Xu JM, Xu AM, Dai RP, Zhou ZG. Adipocyte Fatty Acid-Binding Protein Promotes Palmitate-Induced Mitochondrial Dysfunction and Apoptosis in Macrophages. Front Immunol 2018; 9:81. [PMID: 29441065 PMCID: PMC5797554 DOI: 10.3389/fimmu.2018.00081] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Accepted: 01/11/2018] [Indexed: 11/13/2022] Open
Abstract
A high level of circulating free fatty acids (FFAs) is known to be an important trigger for macrophage apoptosis during the development of atherosclerosis. However, the underlying mechanism by which FFAs result in macrophage apoptosis is not well understood. In cultured human macrophage Thp-1 cells, we showed that palmitate (PA), the most abundant FFA in circulation, induced excessive reactive oxidative substance production, increased malondialdehyde concentration, and decreased adenosine triphosphate levels. Furthermore, PA treatment also led to mitochondrial dysfunction, including the decrease of mitochondrial number, the impairment of respiratory complex IV and succinate dehydrogenase activity, and the reduction of mitochondrial membrane potential. Mitochondrial apoptosis was also detected after PA treatment, indicated by a decrease in cytochrome c release, downregulation of Bcl-2, upregulation of Bax, and increased caspase-3 activity. PA treatment upregulated the expression of adipocyte fatty acid-binding protein (A-FABP), a critical regulator of fatty acid trafficking and lipid metabolism. Inhibition of A-FABP with BMS309403, a small-molecule A-FABP inhibitor, almost reversed all of these indexes. Thus, this study suggested that PA-mediated macrophage apoptosis through A-FABP upregulation, which subsequently resulted in mitochondrial dysfunction and reactive oxidative stress. Inhibition of A-FABP may be a potential therapeutic target for macrophage apoptosis and to delay the progress of atherosclerosis.
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Affiliation(s)
- Hui Li
- Department of Anesthesiology, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Yang Xiao
- Department of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Lin Tang
- Department of Anesthesiology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Feng Zhong
- Department of Anesthesiology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Gan Huang
- Department of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jun-Mei Xu
- Department of Anesthesiology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Ai-Min Xu
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Ru-Ping Dai
- Department of Anesthesiology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Zhi-Guang Zhou
- Department of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, China
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13
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Carpentier AC. Abnormal Myocardial Dietary Fatty Acid Metabolism and Diabetic Cardiomyopathy. Can J Cardiol 2018; 34:605-614. [PMID: 29627307 DOI: 10.1016/j.cjca.2017.12.029] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/08/2017] [Accepted: 12/19/2017] [Indexed: 12/13/2022] Open
Abstract
Patients with diabetes are at very high risk of hospitalization and death from heart failure. Increased prevalence of coronary heart disease, hypertension, autonomic neuropathy, and kidney failure all play a role in this increased risk. However, cardiac metabolic abnormalities are now recognized to play a role in this increased risk. Increased reliance on fatty acids to produce energy might predispose the diabetic heart to oxidative stress and ischemic damage. Intramyocellular accumulation of toxic lipid metabolites leads to a number of cellular abnormalities that might also contribute to cardiac remodelling and cardiac dysfunction. However, fatty acid availability from circulation and from intracellular lipid droplets to fuel the heart is critical to maintain its function. Fatty acids delivery to the heart is very complex and includes plasma nonesterified fatty acid flux as well as triglyceride-rich lipoprotein-mediated transport. Although many studies have shown a cross-sectional association between enhanced fatty acid delivery to the heart and reduction in left ventricular function in subjects with prediabetes and diabetes, these mechanisms change very rapidly during type 2 diabetes treatment. The present review focuses on the role of fatty acids in cardiac function, with particular emphasis on the possible role of early abnormalities of dietary fatty acid metabolism in the development of diabetic cardiomyopathy.
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Affiliation(s)
- André C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Québec, Canada.
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14
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Integrated Immunomodulatory Mechanisms through which Long-Chain n-3 Polyunsaturated Fatty Acids Attenuate Obese Adipose Tissue Dysfunction. Nutrients 2017; 9:nu9121289. [PMID: 29186929 PMCID: PMC5748740 DOI: 10.3390/nu9121289] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/14/2017] [Accepted: 11/16/2017] [Indexed: 12/13/2022] Open
Abstract
Obesity is a global health concern with rising prevalence that increases the risk of developing other chronic diseases. A causal link connecting overnutrition, the development of obesity and obesity-associated co-morbidities is visceral adipose tissue (AT) dysfunction, characterized by changes in the cellularity of various immune cell populations, altered production of inflammatory adipokines that sustain a chronic state of low-grade inflammation and, ultimately, dysregulated AT metabolic function. Therefore, dietary intervention strategies aimed to halt the progression of obese AT dysfunction through any of the aforementioned processes represent an important active area of research. In this connection, fish oil-derived dietary long-chain n-3 polyunsaturated fatty acids (PUFA) in the form of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been demonstrated to attenuate obese AT dysfunction through multiple mechanisms, ultimately affecting AT immune cellularity and function, adipokine production, and metabolic signaling pathways, all of which will be discussed herein.
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15
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Søndergaard E, Johansen RF, Jensen MD, Nielsen S. Postprandial VLDL-TG metabolism in type 2 diabetes. Metabolism 2017; 75:25-35. [PMID: 28964326 DOI: 10.1016/j.metabol.2017.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/26/2017] [Accepted: 07/05/2017] [Indexed: 01/22/2023]
Abstract
BACKGROUND Type 2 diabetes is associated with excess postprandial lipemia due to accumulation of chylomicrons and VLDL particles. This is a risk factor for development of cardiovascular disease. However, whether the excess lipemia is associated with an impaired suppression of VLDL-TG secretion and/or reduced clearance into adipose tissue is unknown. OBJECTIVE We measured the postprandial VLDL-TG secretion, clearance and adipose tissue storage to test the hypothesis that impaired postprandial suppression of VLDL-TG secretion, combined with impaired VLDL-TG storage in adipose tissue, is associated with excess postprandial lipemia. DESIGN We studied 11 men with type 2 diabetes and 10 weight-matched non-diabetic men using ex-vivo labeled VLDL-TG tracers during an oral high-fat mixed-meal tolerance test to measure postprandial VLDL-TG secretion, clearance and storage. In addition, adipose tissue biopsies were analyzed for LPL activity and cellular storage factors. RESULTS Men with type 2 diabetes had greater postprandial VLDL-TG concentration compared to non-diabetic men. However, postprandial VLDL-TG secretion rate was similar in the two groups with equal suppression of VLDL-TG secretion rate (≈50%) and clearance rate. In addition, postprandial VLDL-TG storage was similar in the two groups in both upper body and lower body subcutaneous adipose tissue. CONCLUSIONS Despite greater postprandial VLDL-TG concentration, men with type 2 diabetes have similar postprandial suppression of VLDL-TG secretion and a similar ability to store VLDL-TG in adipose tissue compared to non-diabetic men. This may indicate that abnormalities in postprandial VLDL-TG metabolism are a consequence of obesity/insulin resistance more than a result of type 2 diabetes per se.
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Affiliation(s)
- Esben Søndergaard
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark; Danish Diabetes Academy, Odense University Hospital, Kløvervænget 10, Entrance 112, 3rd floor, 5000 Odense C, Denmark; Endocrine Research Unit, Mayo Clinic, 1216 2nd St SW, Rochester, MN 55902, USA.
| | - Rakel Fuglsang Johansen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark
| | - Michael D Jensen
- Endocrine Research Unit, Mayo Clinic, 1216 2nd St SW, Rochester, MN 55902, USA
| | - Søren Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark
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16
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Schrauwen-Hinderling VB, Carpentier AC. Molecular imaging of postprandial metabolism. J Appl Physiol (1985) 2017; 124:504-511. [PMID: 28495844 DOI: 10.1152/japplphysiol.00212.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Disordered postprandial metabolism of energy substrates is one of the main defining features of prediabetes and contributes to the development of several chronic diseases associated with obesity, such as type 2 diabetes and cardiovascular diseases. Postprandial energy metabolism has been studied using classical isotopic tracer approaches that are limited by poor access to splanchnic metabolism and highly dynamic and complex exchanges of energy substrates involving multiple organs and systems. Advances in noninvasive molecular imaging modalities, such as PET and MRI/magnetic resonance spectroscopy (MRS), have recently allowed important advances in our understanding of postprandial energy metabolism in humans. The present review describes some of these recent advances, with particular focus on glucose and fatty acid metabolism in the postprandial state, and discusses current gaps in knowledge and new perspectives of application of PET and MRI/MRS for the investigation and treatment of human metabolic diseases.
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Affiliation(s)
- Vera B Schrauwen-Hinderling
- Department of Radiology and Human Biology and Human Movement Sciences, Maastricht University Medical Center , Maastricht , The Netherlands
| | - André C Carpentier
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke , Sherbrooke, Québec , Canada
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17
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Blondin DP, Tingelstad HC, Noll C, Frisch F, Phoenix S, Guérin B, Turcotte ÉE, Richard D, Haman F, Carpentier AC. Dietary fatty acid metabolism of brown adipose tissue in cold-acclimated men. Nat Commun 2017; 8:14146. [PMID: 28134339 PMCID: PMC5290270 DOI: 10.1038/ncomms14146] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 12/02/2016] [Indexed: 12/13/2022] Open
Abstract
In rodents, brown adipose tissue (BAT) plays an important role in producing heat to defend against the cold and can metabolize large amounts of dietary fatty acids (DFA). The role of BAT in DFA metabolism in humans is unknown. Here we show that mild cold stimulation (18 °C) results in a significantly greater fractional DFA extraction by BAT relative to skeletal muscle and white adipose tissue in non-cold-acclimated men given a standard liquid meal containing the long-chain fatty acid PET tracer, 14(R,S)-[18F]-fluoro-6-thia-heptadecanoic acid (18FTHA). However, the net contribution of BAT to systemic DFA clearance is comparatively small. Despite a 4-week cold acclimation increasing BAT oxidative metabolism 2.6-fold, BAT DFA uptake does not increase further. These findings show that cold-stimulated BAT can contribute to the clearance of DFA from circulation but its contribution is not as significant as the heart, liver, skeletal muscles or white adipose tissues. Brown adipose tissue (BAT) takes up and burns fatty acids for thermogenesis in mice. Here the authors use PET to show that, in humans, cold stimulation increases BAT dietary fatty acid uptake from plasma and oxidative metabolism, although, unlike mice, human BAT takes up less fatty acids than other metabolic tissues.
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Affiliation(s)
- Denis P Blondin
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, QC, Canada J1H 5N4
| | - Hans C Tingelstad
- Faculty of Health Sciences, University of Ottawa, 125 University Pvt. Ottawa, ON, Canada K1N 6N5
| | - Christophe Noll
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, QC, Canada J1H 5N4
| | - Frédérique Frisch
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, QC, Canada J1H 5N4
| | - Serge Phoenix
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, QC, Canada J1H 5N4.,Department of Nuclear Medicine and Radiobiology, Centre d'imagerie Moléculaire de Sherbrooke, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, QC, Canada J1H 5N4
| | - Brigitte Guérin
- Department of Nuclear Medicine and Radiobiology, Centre d'imagerie Moléculaire de Sherbrooke, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, QC, Canada J1H 5N4
| | - Éric E Turcotte
- Department of Nuclear Medicine and Radiobiology, Centre d'imagerie Moléculaire de Sherbrooke, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, QC, Canada J1H 5N4
| | - Denis Richard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, 2725, chemin Sainte-Foy, Québec, QC, Canada G1V 4G5
| | - François Haman
- Faculty of Health Sciences, University of Ottawa, 125 University Pvt. Ottawa, ON, Canada K1N 6N5
| | - André C Carpentier
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, QC, Canada J1H 5N4
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18
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Abstract
The demonstration of the presence of metabolically active brown adipose tissue (BAT) in adult humans using positron emission tomography (PET) over the past decade has lead to the rapid development of our knowledge regarding the role of BAT in energy metabolism in animal models and in humans. Although animal models continue to provide highly valuable information regarding the mechanisms regulating BAT development, mass and metabolic functions, these studies led to many assumptions that have been at best only partially verified in humans so far. Combined to some limitations of the current investigation approaches used in humans, this has lead to speculation on the potential role of BAT dysfunction in the development of cardiometabolic disorders and on the potential of BAT metabolic activation to treat these conditions. Here we propose a critical review of the evidence for the implication of BAT in cardiometabolic health.
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Affiliation(s)
- Denis P Blondin
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Canada
| | - André C Carpentier
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Canada.
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19
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Labbé SM, Caron A, Chechi K, Laplante M, Lecomte R, Richard D. Metabolic activity of brown, "beige," and white adipose tissues in response to chronic adrenergic stimulation in male mice. Am J Physiol Endocrinol Metab 2016; 311:E260-8. [PMID: 27143559 PMCID: PMC4967144 DOI: 10.1152/ajpendo.00545.2015] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/27/2016] [Indexed: 11/22/2022]
Abstract
Classical brown adipocytes such as those found in interscapular brown adipose tissue (iBAT) represent energy-burning cells, which have been postulated to play a pivotal role in energy metabolism. Brown adipocytes can also be found in white adipose tissue (WAT) depots [e.g., inguinal WAT (iWAT)] following adrenergic stimulation, and they have been referred to as "beige" adipocytes. Whether the presence of these adipocytes, which gives iWAT a beige appearance, can confer a white depot with some thermogenic activity remains to be seen. In consequence, we designed the present study to investigate the metabolic activity of iBAT, iWAT, and epididymal white depots in mice. Mice were either 1) kept at thermoneutrality (30°C), 2) kept at 30°C and treated daily for 14 days with an adrenergic agonist [CL-316,243 (CL)], or 3) housed at 10°C for 14 days. Metabolic activity was assessed using positron emission tomography imaging with fluoro-[(18)F]deoxyglucose (glucose uptake), fluoro-[(18)F]thiaheptadecanoic acid (fatty acid uptake), and [(11)C]acetate (oxidative activity). In each group, substrate uptakes and oxidative activity were measured in anesthetized mice in response to acute CL. Our results revealed iBAT as a major site of metabolic activity, which exhibited enhanced glucose and nonesterified fatty acid uptakes and oxidative activity in response to chronic cold and CL. On the other hand, beige adipose tissue failed to exhibit appreciable increase in oxidative activity in response to chronic cold and CL. Altogether, our results suggest that the contribution of beige fat to acute-CL-induced metabolic activity is low compared with that of iBAT, even after sustained adrenergic stimulation.
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Affiliation(s)
- Sébastien M Labbé
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Canada; and
| | - Alexandre Caron
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Canada; and
| | - Kanta Chechi
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Canada; and
| | - Mathieu Laplante
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Canada; and
| | - Roger Lecomte
- Departments of Nuclear Medicine and Radiobiology, Centre d'imagerie moléculaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Canada
| | - Denis Richard
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, Canada; and
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20
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Noll C, Kunach M, Frisch F, Bouffard L, Dubreuil S, Jean-Denis F, Phoenix S, Cunnane SC, Guérin B, Turcotte EE, Carpentier AC. Seven-Day Caloric and Saturated Fat Restriction Increases Myocardial Dietary Fatty Acid Partitioning in Impaired Glucose-Tolerant Subjects. Diabetes 2015. [PMID: 26224886 DOI: 10.2337/db15-0337] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Subjects with impaired glucose tolerance (IGT) have increased myocardial partitioning of dietary fatty acids (DFAs) with left ventricular dysfunction, both of which are improved by modest weight loss over 1 year induced by lifestyle changes. Here, we determined the effects of a 7-day hypocaloric diet (-500 kcal/day) low in saturated fat (<7% of energy) (LOWCAL study) versus isocaloric with the usual amount saturated fat (∼10% of energy) diet (ISOCAL) on DFA metabolism in subjects with IGT. Organ-specific DFA partitioning and cardiac and hepatic DFA fractional uptake rates were measured in 15 IGT subjects (7 males/8 females) using the oral 14(R,S)-[18F]-fluoro-6-thia-heptadecanoic acid positron emission tomography method after 7 days of an ISOCAL diet versus a LOWCAL diet using a randomized crossover design. The LOWCAL diet led to reductions in weight and postprandial insulin area under the curve. Myocardial DFA partitioning over 6 h was increased after the LOWCAL diet (2.3 ± 0.1 vs. 1.9 ± 0.2 mean standard uptake value, P < 0.04). However, the early (90-120 min) myocardial DFA fractional uptake was unchanged after the LOWCAL diet (0.055 ± 0.025 vs. 0.046 ± 0.009 min(-1), P = 0.7). Liver DFA partitioning was unchanged, but liver fractional uptake of DFA tended to be increased. Very short-term caloric and saturated fat dietary restrictions do not lead to the same changes in organ-specific DFA metabolism as those associated with weight loss in subjects with IGT.
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Affiliation(s)
- Christophe Noll
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Margaret Kunach
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Frédérique Frisch
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Lucie Bouffard
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Stéphanie Dubreuil
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Farrah Jean-Denis
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Serge Phoenix
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Quebec, Canada
| | - Stephen C Cunnane
- Research Center on Aging, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Brigitte Guérin
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Quebec, Canada
| | - Eric E Turcotte
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Quebec, Canada
| | - André C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada Department of Nuclear Medicine and Radiobiology, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Quebec, Canada
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Blondin DP, Labbé SM, Noll C, Kunach M, Phoenix S, Guérin B, Turcotte ÉE, Haman F, Richard D, Carpentier AC. Selective Impairment of Glucose but Not Fatty Acid or Oxidative Metabolism in Brown Adipose Tissue of Subjects With Type 2 Diabetes. Diabetes 2015; 64:2388-97. [PMID: 25677914 DOI: 10.2337/db14-1651] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 02/05/2015] [Indexed: 11/13/2022]
Abstract
Spontaneous glucose uptake by brown adipose tissue (BAT) is lower in overweight or obese individuals and in diabetes. However, BAT metabolism has not been previously investigated in patients with type 2 diabetes during controlled cold exposure. Using positron emission tomography with (11)C-acetate, (18)F-fluoro-deoxyglucose ((18)FDG), and (18)F-fluoro-thiaheptadecanoic acid ((18)FTHA), a fatty acid tracer, BAT oxidative metabolism and perfusion and glucose and nonesterified fatty acid (NEFA) turnover were determined in men with well-controlled type 2 diabetes and age-matched control subjects under experimental cold exposure designed to minimize shivering. Despite smaller volumes of (18)FDG-positive BAT and lower glucose uptake per volume of BAT compared with young healthy control subjects, cold-induced oxidative metabolism and NEFA uptake per BAT volume and an increase in total body energy expenditure did not differ in patients with type 2 diabetes or their age-matched control subjects. The reduction in (18)FDG-positive BAT volume and BAT glucose clearance were associated with a reduction in BAT radiodensity and perfusion. (18)FDG-positive BAT volume and the cold-induced increase in BAT radiodensity were associated with an increase in systemic NEFA turnover. These results show that cold-induced NEFA uptake and oxidative metabolism are not defective in type 2 diabetes despite reduced glucose uptake per BAT volume and BAT "whitening."
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Affiliation(s)
- Denis P Blondin
- Department of Medicine, Centre de Recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Quebec, Canada
| | - Sébastien M Labbé
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada
| | - Christophe Noll
- Department of Medicine, Centre de Recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Quebec, Canada
| | - Margaret Kunach
- Department of Medicine, Centre de Recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Quebec, Canada
| | - Serge Phoenix
- Department of Medicine, Centre de Recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Quebec, Canada Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Brigitte Guérin
- Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Éric E Turcotte
- Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - François Haman
- Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Denis Richard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada
| | - André C Carpentier
- Department of Medicine, Centre de Recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Quebec, Canada
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Blondin DP, Labbé SM, Turcotte EE, Haman F, Richard D, Carpentier AC. A critical appraisal of brown adipose tissue metabolism in humans. ACTA ACUST UNITED AC 2015. [DOI: 10.2217/clp.15.14] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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23
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Labbé SM, Noll C, Grenier-Larouche T, Kunach M, Bouffard L, Phoenix S, Guérin B, Baillargeon JP, Langlois MF, Turcotte EE, Carpentier AC. Improved cardiac function and dietary fatty acid metabolism after modest weight loss in subjects with impaired glucose tolerance. Am J Physiol Endocrinol Metab 2014; 306:E1388-96. [PMID: 24760989 DOI: 10.1152/ajpendo.00638.2013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Using a novel positron emission tomography (PET) method with oral administration of 14(R,S)-[¹⁸F]-fluoro-6-thia-heptadecanoic acid (¹⁸FTHA), we recently demonstrated that subjects with impaired glucose tolerance (IGT) display an impairment in cardiac function associated with increased myocardial uptake of dietary fatty acids. Here, we determined whether modest weight loss induced by lifestyle changes might improve these cardiac metabolic and functional abnormalities. Nine participants with IGT, enrolled in a one-year lifestyle intervention trial, were invited to undergo determination of organ-specific postprandial dietary fatty acids partition using the oral ¹⁸FTHA method, and cardiac function and oxidative metabolic index using PET [¹¹C]acetate kinetics with ECG-gated PET ventriculography before and after the intervention. The intervention resulted in significant weight loss and reduction of waist circumference, with reduced postprandial plasma glucose, insulin, and triglycerides excursion. We observed a significant increase in stroke volume, cardiac output, and left ventricular ejection fraction associated with reduced myocardial oxidative metabolic index and fractional dietary fatty acid uptake. Modest weight loss corrects the exaggerated myocardial channeling of dietary fatty acids and improves myocardial energy substrate metabolism and function in IGT subjects.
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Affiliation(s)
- Sébastien M Labbé
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Québec, Canada; and
| | - Christophe Noll
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Québec, Canada; and
| | - Thomas Grenier-Larouche
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Québec, Canada; and
| | - Margaret Kunach
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Québec, Canada; and
| | - Lucie Bouffard
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Québec, Canada; and
| | - Serge Phoenix
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Québec, Canada; and Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Québec, Canada
| | - Brigitte Guérin
- Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Québec, Canada
| | - Jean-Patrice Baillargeon
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Québec, Canada; and
| | - Marie-France Langlois
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Québec, Canada; and
| | - Eric E Turcotte
- Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Québec, Canada
| | - André C Carpentier
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, Québec, Canada; and
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Honka H, Hannukainen JC, Tarkia M, Karlsson H, Saunavaara V, Salminen P, Soinio M, Mikkola K, Kudomi N, Oikonen V, Haaparanta-Solin M, Roivainen A, Parkkola R, Iozzo P, Nuutila P. Pancreatic metabolism, blood flow, and β-cell function in obese humans. J Clin Endocrinol Metab 2014; 99:E981-90. [PMID: 24527718 DOI: 10.1210/jc.2013-4369] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
CONTEXT Glucolipotoxicity is believed to induce pancreatic β-cell dysfunction in obesity. Previously, it has not been possible to study pancreatic metabolism and blood flow in humans. OBJECTIVE The objective of the study was to investigate whether pancreatic metabolism and blood flow are altered in obesity using positron emission tomography (PET). In the preclinical part, the method was validated in animals. DESIGN This was a cross-sectional study. SETTING The study was conducted in a clinical research center. PARTICIPANTS Human studies consisted of 52 morbidly obese and 25 healthy age-matched control subjects. Validation experiments were done with rodents and pigs. INTERVENTIONS PET and magnetic resonance imaging studies using a glucose analog ([(18)F]fluoro-2-deoxy-d-glucose), a palmitate analog [14(R,S)-[(18)F]fluoro-6-thia-heptadecanoic acid], and radiowater ([(15)O]H2O) were performed. In animals, a comparison between ex vivo and in vivo data was performed. MAIN OUTCOME MEASURES Pancreatic glucose/fatty acid (FA) uptake, fat accumulation, and blood flow parameters of β-cell function were measured. RESULTS PET proved to be a feasible method to measure pancreatic metabolism. Compared with healthy participants, obese participants had elevated pancreatic FA uptake (P < .0001), more fat accumulation (P = .0001), lowered glucose uptake both during fasting and euglycemic hyperinsulinemia, and blunted blood flow (P < .01) in the pancreas. Blood flow, FA uptake, and fat accumulation were negatively associated with multiple markers of β-cell function. CONCLUSIONS Obesity leads to changes in pancreatic energy metabolism with a substrate shift from glucose to FAs. In morbidly obese humans, impaired pancreatic blood flow may contribute to β-cell dysfunction and in the pathogenesis of type 2 diabetes.
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Affiliation(s)
- Henri Honka
- Turku PET Centre (H.H., J.C.H., M.T., H.K., V.S., K.M., V.O., M.H.-S., A.R., R.P., P.N.), University of Turku, Turku 20520, Finland; Division of Digestive Surgery and Urology (P.S.) and Department of Endocrinology (P.N., M.S.), Turku University Hospital, Turku 20520, Finland; Faculty of Medicine (N.K.), University of Kagawa, Kagawa 760-0016, Japan; Department of Radiology (R.P.), University of Tampere, Tampere 33014, Finland; Institute of Biomedical Engineering (P.I.), National Research Council, 35128 Padua, Italy; and Institute of Clinical Physiology (P.I.), National Research Council, 56124 Pisa, Italy
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25
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Fricano CJ, Despenza T, Frazel PW, Li M, O'Malley AJ, Westbrook GL, Luikart BW. Fatty acids increase neuronal hypertrophy of Pten knockdown neurons. Front Mol Neurosci 2014; 7:30. [PMID: 24795563 PMCID: PMC4006057 DOI: 10.3389/fnmol.2014.00030] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 04/01/2014] [Indexed: 01/22/2023] Open
Abstract
Phosphatase and tensin homolog (Pten) catalyzes the reverse reaction of PI3K by dephosphorylating PIP3 to PIP2. This negatively regulates downstream Akt/mTOR/S6 signaling resulting in decreased cellular growth and proliferation. Co-injection of a lentivirus knocking Pten down with a control lentivirus allows us to compare the effects of Pten knockdown between individual neurons within the same animal. We find that knockdown of Pten results in neuronal hypertrophy by 21 days post-injection. This neuronal hypertrophy is correlated with increased p-S6 and p-mTOR in individual neurons. We used this system to test whether an environmental factor that has been implicated in cellular hypertrophy could influence the severity of the Pten knockdown-induced hypertrophy. Implantation of mini-osmotic pumps delivering fatty acids results in increased neuronal hypertrophy and p-S6/p-mTOR staining. These hypertrophic effects were reversed in response to rapamycin treatment. However, we did not observe a similar increase in hypertrophy in response to dietary manipulations of fatty acids. Thus, we conclude that by driving growth signaling with fatty acids and knocking down a critical regulator of growth, Pten, we are able to observe an additive morphological phenotype of increased soma size mediated by the mTOR pathway.
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Affiliation(s)
- Catherine J Fricano
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
| | - Tyrone Despenza
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
| | - Paul W Frazel
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
| | - Meijie Li
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
| | - A James O'Malley
- The Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
| | - Gary L Westbrook
- The Vollum Institute, Oregon Health and Science University Portland, OR, USA
| | - Bryan W Luikart
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
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26
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Blondin DP, Labbé SM, Tingelstad HC, Noll C, Kunach M, Phoenix S, Guérin B, Turcotte EE, Carpentier AC, Richard D, Haman F. Increased brown adipose tissue oxidative capacity in cold-acclimated humans. J Clin Endocrinol Metab 2014; 99:E438-46. [PMID: 24423363 PMCID: PMC4213359 DOI: 10.1210/jc.2013-3901] [Citation(s) in RCA: 225] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
CONTEXT Recent studies examining brown adipose tissue (BAT) metabolism in adult humans have provided convincing evidence of its thermogenic potential and role in clearing circulating glucose and fatty acids under acute mild cold exposure. In contrast, early indications suggest that BAT metabolism is defective in obesity and type 2 diabetes, which may have important pathological and therapeutic implications. Although many mammalian models have demonstrated the phenotypic flexibility of this tissue through chronic cold exposure, little is known about the metabolic plasticity of BAT in humans. OBJECTIVE Our objective was to determine whether 4 weeks of daily cold exposure could increase both the volume of metabolically active BAT and its oxidative capacity. DESIGN Six nonacclimated men were exposed to 10°C for 2 hours daily for 4 weeks (5 d/wk), using a liquid-conditioned suit. Using electromyography combined with positron emission tomography with [(11)C]acetate and [(18)F]fluorodeoxyglucose, shivering intensity and BAT oxidative metabolism, glucose uptake, and volume before and after 4 weeks of cold acclimation were examined under controlled acute cold-exposure conditions. RESULTS The 4-week acclimation protocol elicited a 45% increase in BAT volume of activity (from 66 ± 30 to 95 ± 28 mL, P < .05) and a 2.2-fold increase in cold-induced total BAT oxidative metabolism (from 0.725 ± 0.300 to 1.591 ± 0.326 mL·s(-1), P < .05). Shivering intensity was not significantly different before compared with after acclimation (2.1% ± 0.7% vs 2.0% ± 0.5% maximal voluntary contraction, respectively). Fractional glucose uptake in BAT increased after acclimation (from 0.035 ± 0.014 to 0.048 ± 0.012 min(-1)), and net glucose uptake also trended toward an increase (from 163 ± 60 to 209 ± 50 nmol·g(-1)·min(-1)). CONCLUSIONS These findings demonstrate that daily cold exposure not only increases the volume of metabolically active BAT but also increases its oxidative capacity and thus its contribution to cold-induced thermogenesis.
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Affiliation(s)
- Denis P Blondin
- Faculty of Health Sciences (D.P.B., H.C.T., F.H.), University of Ottawa, Ottawa, Ontario, Canada K1N 6N5; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (S.M.L., D.R.), Université Laval, Québec City, Québec, Canada G1V 4G5; Department of Medicine (C.N., M.K., S.P., A.C.C.), Centre de Recherche Clinique Etienne-Le Bel, Université de Sherbrooke, Sherbrooke, Québec, Canada; and Department of Nuclear Medicine and Radiobiology (S.P., B.G., E.E.T.), Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
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27
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Casanova E, Baselga-Escudero L, Ribas-Latre A, Arola-Arnal A, Bladé C, Arola L, Salvadó MJ. Omega-3 polyunsaturated fatty acids and proanthocyanidins improve postprandial metabolic flexibility in rat. Biofactors 2014; 40:146-56. [PMID: 23983179 DOI: 10.1002/biof.1129] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/01/2013] [Accepted: 07/03/2013] [Indexed: 02/06/2023]
Abstract
Postprandial lipemia influences the development of atherosclerosis, which itself constitutes a risk factor for the development of cardiovascular diseases. The introduction of bioactive compounds may prevent these deleterious effects. Proanthocyanidins are potent antioxidants that have hypolipidemic properties, while omega-3 polyunsaturated fatty acids (ω3 PUFAs) stimulate fatty acid oxidation and gene expression programs, controlling mitochondrial functions. In this study, we investigated the effects of acute treatment of ω3 PUFAs and proanthocyanidins on the metabolic flexibility and lipid handling profiles in the skeletal muscle and adipose tissue of rats that were raised on diets, high in saturated fatty acids. For this, oil rich in docosahexaenoic (DHA-OR), grape seed proanthocyanidins extract (GSPE), or both substances (GSPE + DHA-OR) were administered with an overload of lard oil to healthy Wistar rats. Our results indicate that the addition of DHA-OR to lard oil increases insulin sensitivity and redirects fatty acids toward skeletal muscle, thereby activating fatty acid oxidation. We also observed an improvement in adipose mitochondrial functionality and uncoupling. In contrast, GSPE lowers lipidemia, prevents muscle reactive oxygen species (ROS) production and damage, furthermore, activates mitochondrial biogenesis and lipogenesis in adipose tissue. The addition of GSPE+DHA-OR to lard resulted in nearly all the effects of DHA-OR and GSPE administered individually, but the combined administration resulted in a more attenuated profile.
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Affiliation(s)
- Ester Casanova
- Department of Biochemistry and Biotechnology, Nutrigenomics Research Group, Universitat Rovira I Virgili, 43007, Tarragona, Spain
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28
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Cignarelli A, Giorgino F, Vettor R. Pharmacologic agents for type 2 diabetes therapy and regulation of adipogenesis. Arch Physiol Biochem 2013; 119:139-50. [PMID: 23724947 DOI: 10.3109/13813455.2013.796996] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The close link between type 2 diabetes and excess body weight highlights the need to consider the effects on weight of different treatments used for correction of hyperglycaemia. Indeed, specific currently available diabetes therapies can cause weight gain, including insulin and its analogues, sulphonylureas, and thiazolidinediones, while others, such as metformin and the GLP-1 receptor agonists, can promote weight loss. Excess body weight in patients with diabetes is largely due to expansion of adipose tissue, and these drugs could interfere with the mechanisms underlying the expansion and differentiation of adipocyte precursors. Almost all anti-diabetes drugs could also potentially affect adipocyte metabolism directly, by modulating lipogenesis, lipolysis, and fat oxidation. This review will examine the available evidence for specific effects of various anti-diabetes drugs on adipose tissue development and function with the ultimate goal of increasing our understanding of how pharmacological agents can modulate energy balance and body fat.
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Affiliation(s)
- A Cignarelli
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari "Aldo Moro" , Bari , Italy and
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29
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Carpentier AC. The 2012 CDA-CIHR INMD young investigator award lecture: dysfunction of adipose tissues and the mechanisms of ectopic fat deposition in type 2 diabetes. Can J Diabetes 2013; 37:109-14. [PMID: 24070801 DOI: 10.1016/j.jcjd.2013.03.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 03/12/2013] [Accepted: 03/12/2013] [Indexed: 12/20/2022]
Abstract
Ectopic fat deposition in skeletal muscles, liver, heart, and other tissues has been closely linked with the development of lean tissues' insulin resistance and progression toward type 2 diabetes mellitus. Mechanisms of overexposure of these tissues to fatty acids include increased de novo lipogenesis, impaired fatty acid oxidation and increased fatty acid flux to these organs. White adipose tissues are the main organs responsible for the regulation of circulating fatty acids. It has been clearly demonstrated that pre-diabetes individuals and individuals with diabetes display impaired adipose tissue dietary fatty acid storage that may lead to increased circulating flux and exaggerated lean tissue fatty acid exposure. Additionally, brown adipose tissue depots are less metabolically active in individuals with type 2 diabetes. We have developed a series of novel in vivo investigative tools using positron emission tomography to comprehensively assess postprandial interorgan fatty acid partitioning and white and brown adipose tissue metabolism in subjects with pre-diabetes and type 2 diabetes. Our findings shed new lights into the sophisticated mechanisms that regulate fatty acid partitioning and energy homeostasis during the development of type 2 diabetes. New links between abnormal dietary fatty acid metabolism and early myocardial metabolic and functional defects are now being uncovered in humans with the hope to find novel ways to predict and avoid the devastating complications of diabetes.
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Affiliation(s)
- André C Carpentier
- CIHR-GSK Chair in Diabetes Department of Medicine, Division of Endocrinology, Université de Sherbrooke, Centre de recherche clinique Étienne-Le Bel, Centre hospitalier universitaire de Sherbrooke, Sherbrooke, Québec, Canada.
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30
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Jonkers RAM, van Loon LJC, Nicolay K, Prompers JJ. In vivo postprandial lipid partitioning in liver and skeletal muscle in prediabetic and diabetic rats. Diabetologia 2013; 56:618-26. [PMID: 23238787 PMCID: PMC3563947 DOI: 10.1007/s00125-012-2792-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 11/12/2012] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Insulin resistance and type 2 diabetes have been associated with ectopic lipid deposition. This study investigates the derangements in postprandial lipid handling in liver and skeletal muscle tissue at different stages during the pathogenesis of type 2 diabetes in a rat model. METHODS Four groups (n = 6) of male Zucker diabetic fatty rats were used for this study: prediabetic fa/fa rats and healthy fa/+ littermates at the age of 6 weeks, and diabetic fa/fa rats and healthy fa/+ littermates at the age of 12 weeks. In vivo (1)H-[(13)C] magnetic resonance spectroscopy measurements were performed in liver and tibialis anterior muscle at baseline and 4, 24 and 48 h after oral administration of 1.5 g [U-(13)C]algal lipid mixture per kilogram body weight. Total and (13)C-labelled intracellular lipid contents were determined from the magnetic resonance spectra. RESULTS In both prediabetic and diabetic rats, total lipid contents in muscle and liver were substantially higher than in healthy controls and this was accompanied by a 2.3-fold greater postprandial lipid uptake in the liver (p < 0.001). Interestingly, in prediabetic rats, skeletal muscle appeared to be protected from excess lipid uptake whereas after developing overt diabetes muscle lipid uptake was 3.4-fold higher than in controls (p < 0.05). Muscle lipid use was significantly lower in prediabetic and diabetic muscle, indicative of impairments in lipid oxidation. CONCLUSIONS/INTERPRETATION In vivo postprandial lipid handling is disturbed in both liver and skeletal muscle tissue in prediabetic and diabetic rats, but the uptake of dietary lipids in muscle is only increased after the development of overt diabetes.
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Affiliation(s)
- R. A. M. Jonkers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands
| | - L. J. C. van Loon
- NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Movement Sciences, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - K. Nicolay
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands
| | - J. J. Prompers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands
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31
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Grenier-Larouche T, Labbé SM, Noll C, Richard D, Carpentier AC. Metabolic inflexibility of white and brown adipose tissues in abnormal fatty acid partitioning of type 2 diabetes. INTERNATIONAL JOURNAL OF OBESITY SUPPLEMENTS 2012; 2:S37-42. [PMID: 27152152 PMCID: PMC4850609 DOI: 10.1038/ijosup.2012.21] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Type 2 diabetes (T2D) is characterized by a general dysregulation of postprandial energy substrate partitioning. Although classically described in regard to glucose metabolism, it is now evident that metabolic inflexibility of plasma lipid fluxes is also present in T2D. The organ that is most importantly involved in the latter metabolic defect is the white adipose tissue (WAT). Both catecholamine-induced nonesterified fatty acid mobilization and insulin-stimulated storage of meal fatty acids are impaired in many WAT depots of insulin-resistant individuals. Novel molecular imaging techniques now demonstrate that these defects are linked to increased dietary fatty acid fluxes toward lean organs and myocardial dysfunction in humans. Recent findings also demonstrate functional abnormalities of brown adipose tissues in T2D, thus suggesting that a generalized adipose tissue dysregulation of energy storage and dissipation may be at play in the development of lean tissue energy overload and lipotoxicity.
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Affiliation(s)
- T Grenier-Larouche
- Department of Medicine, Division of Endocrinology, Centre Hospitalier Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - S M Labbé
- Department of Medicine, Division of Endocrinology, Centre Hospitalier Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - C Noll
- Department of Medicine, Division of Endocrinology, Centre Hospitalier Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - D Richard
- Centre de recherche de l'Institut de cardiologie et de pneumologie de Québec, Université Laval Québec, Québec City, Québec, Canada
| | - A C Carpentier
- Department of Medicine, Division of Endocrinology, Centre Hospitalier Université de Sherbrooke, Sherbrooke, Québec, Canada
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32
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Iozzo P. Seeing is believing: dietary fatty acids hurry up from the stomach to the heart of patients with impaired glucose tolerance. Diabetes 2012; 61:2659-60. [PMID: 23093654 PMCID: PMC3478527 DOI: 10.2337/db12-0803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Patricia Iozzo
- Institute of Clinical Physiology, National Research Council (CNR), Pisa, Italy.
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33
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Labbé SM, Grenier-Larouche T, Noll C, Phoenix S, Guérin B, Turcotte EE, Carpentier AC. Increased myocardial uptake of dietary fatty acids linked to cardiac dysfunction in glucose-intolerant humans. Diabetes 2012; 61:2701-10. [PMID: 23093657 PMCID: PMC3478552 DOI: 10.2337/db11-1805] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Impaired cardiac systolic and diastolic function has been observed in preclinical models and in subjects with type 2 diabetes. Using a recently validated positron emission tomography (PET) imaging method with 14(R,S)-[(¹⁸F]-fluoro-6-thia-heptadecanoic acid to quantify organ-specific dietary fatty acid partitioning, we demonstrate in this study that overweight and obese subjects with impaired glucose tolerance (IGT⁺) display significant increase in fractional myocardial dietary fatty acid uptake over the first 6 h postprandial compared with control individuals (IGT⁻). Measured by [¹¹C]acetate with PET, IGT⁺ subjects have a significant increase in myocardial oxidative index. IGT⁺ subjects have significantly reduced left ventricular stroke volume and ejection fraction (LVEF) and tend to display impaired diastolic function, as assessed by PET ventriculography. We demonstrate an inverse relationship between increased myocardial dietary fatty acid partitioning and LVEF. Fractional dietary fatty acid uptake is reduced in subcutaneous abdominal and visceral adipose tissues in IGT⁺ directly associated with central obesity. Fractional dietary fatty acid uptake in skeletal muscles or liver is, however, similar in IGT⁺ versus IGT⁻. The current study demonstrates, for the first time, that excessive myocardial partitioning of dietary fatty acids occurs in prediabetic individuals and is associated with early impairment of left ventricular function and increased myocardial oxidative metabolism.
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Affiliation(s)
- Sébastien M. Labbé
- Department of Medicine, Division of Endocrinology, Centre de Recherche Clinique Etienne-LeBel, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Thomas Grenier-Larouche
- Department of Medicine, Division of Endocrinology, Centre de Recherche Clinique Etienne-LeBel, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Christophe Noll
- Department of Medicine, Division of Endocrinology, Centre de Recherche Clinique Etienne-LeBel, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Serge Phoenix
- Department of Medicine, Division of Endocrinology, Centre de Recherche Clinique Etienne-LeBel, Université de Sherbrooke, Sherbrooke, Québec, Canada
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche Clinique Etienne-LeBel, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Brigitte Guérin
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche Clinique Etienne-LeBel, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Eric E. Turcotte
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche Clinique Etienne-LeBel, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - André C. Carpentier
- Department of Medicine, Division of Endocrinology, Centre de Recherche Clinique Etienne-LeBel, Université de Sherbrooke, Sherbrooke, Québec, Canada
- Corresponding author: André C. Carpentier,
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Ramos-Roman MA, Lapidot SA, Phair RD, Parks EJ. Insulin activation of plasma nonesterified fatty acid uptake in metabolic syndrome. Arterioscler Thromb Vasc Biol 2012; 32:1799-808. [PMID: 22723441 DOI: 10.1161/atvbaha.112.250019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Insulin control of fatty acid metabolism has long been deemed dominated by suppression of adipose lipolysis. The goal of the present study was to test the hypothesis that this single role of insulin is insufficient to explain observed fatty acid dynamics. METHODS AND RESULTS Fatty acid kinetics were measured during a meal tolerance test and insulin sensitivity assessed by intravenous glucose tolerance test in overweight human subjects (n=15; body mass index, 35.8 ± 7.1 kg/m(2)). Non-steady state tracer kinetic models were formulated and tested using ProcessDB software. Suppression of adipose fatty acid release, by itself, could not account for postprandial nonesterified fatty acid concentration changes, but adipose suppression combined with insulin activation of fatty acid uptake was consistent with the measured data. The observed insulin K(m) for nonesterified fatty acid uptake was inversely correlated with both insulin sensitivity of glucose uptake (intravenous glucose tolerance test insulin sensitivity; r=-0.626; P=0.01) and whole body fat oxidation after the meal (r=-0.538; P=0.05). CONCLUSIONS These results support insulin regulation of fatty acid turnover by both release and uptake mechanisms. Activation of fatty acid uptake is consistent with the human data, has mechanistic precedent in cell culture, and highlights a new potential target for therapies aimed at improving the control of fatty acid metabolism in insulin-resistant disease states.
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Affiliation(s)
- Maria A Ramos-Roman
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390-9052, USA
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Hu S, Yao J, Howe AA, Menke BM, Sivitz WI, Spector AA, Norris AW. Peroxisome proliferator-activated receptor γ decouples fatty acid uptake from lipid inhibition of insulin signaling in skeletal muscle. Mol Endocrinol 2012; 26:977-88. [PMID: 22474127 DOI: 10.1210/me.2011-1253] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Peroxisome proliferator-activated receptor γ (PPARγ) is expressed at low levels in skeletal muscle, where it protects against adiposity and insulin resistance via unclear mechanisms. To test the hypothesis that PPARγ directly modulates skeletal muscle metabolism, we created two models that isolate direct PPARγ actions on skeletal myocytes. PPARγ was overexpressed in murine myotubes by adenotransfection and in mouse skeletal muscle by plasmid electroporation. In cultured myotubes, PPARγ action increased fatty acid uptake and incorporation into myocellular lipids, dependent upon a 154 ± 20-fold up-regulation of CD36 expression. PPARγ overexpression more than doubled insulin-stimulated thymoma viral proto-oncogene (AKT) phosphorylation during low lipid availability. Furthermore, in myotubes exposed to palmitate levels that inhibit insulin signaling, PPARγ overexpression increased insulin-stimulated AKT phosphorylation and glycogen synthesis over 3-fold despite simultaneously increasing myocellular palmitate uptake. The insulin signaling enhancement was associated with an increase in activating phosphorylation of phosphoinositide-dependent protein kinase 1 and a normalized expression of palmitate-induced genes that antagonize AKT phosphorylation. In vivo, PPARγ overexpression more than doubled insulin-dependent AKT phosphorylation in lipid-treated mice but did not augment insulin-stimulated glucose uptake. We conclude that direct PPARγ action promotes myocellular storage of energy by increasing fatty acid uptake and esterification while simultaneously enhancing insulin signaling and glycogen formation. However, direct PPARγ action in skeletal muscle is not sufficient to account for the hypoglycemic actions of PPARγ agonists during lipotoxicity.
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Affiliation(s)
- Shanming Hu
- Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
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Ouellet V, Labbé SM, Blondin DP, Phoenix S, Guérin B, Haman F, Turcotte EE, Richard D, Carpentier AC. Brown adipose tissue oxidative metabolism contributes to energy expenditure during acute cold exposure in humans. J Clin Invest 2012; 122:545-52. [PMID: 22269323 PMCID: PMC3266793 DOI: 10.1172/jci60433] [Citation(s) in RCA: 740] [Impact Index Per Article: 61.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 11/16/2011] [Indexed: 11/17/2022] Open
Abstract
Brown adipose tissue (BAT) is vital for proper thermogenesis during cold exposure in rodents, but until recently its presence in adult humans and its contribution to human metabolism were thought to be minimal or insignificant. Recent studies using PET with 18F-fluorodeoxyglucose (18FDG) have shown the presence of BAT in adult humans. However, whether BAT contributes to cold-induced nonshivering thermogenesis in humans has not been proven. Using PET with 11C-acetate, 18FDG, and 18F-fluoro-thiaheptadecanoic acid (18FTHA), a fatty acid tracer, we have quantified BAT oxidative metabolism and glucose and nonesterified fatty acid (NEFA) turnover in 6 healthy men under controlled cold exposure conditions. All subjects displayed substantial NEFA and glucose uptake upon cold exposure. Furthermore, we demonstrated cold-induced activation of oxidative metabolism in BAT, but not in adjoining skeletal muscles and subcutaneous adipose tissue. This activation was associated with an increase in total energy expenditure. We found an inverse relationship between BAT activity and shivering. We also observed an increase in BAT radio density upon cold exposure, indicating reduced BAT triglyceride content. In sum, our study provides evidence that BAT acts as a nonshivering thermogenesis effector in humans.
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Affiliation(s)
- Véronique Ouellet
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
Department of Medicine, Centre de recherche clinique Etienne-Le Bel, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Unité de recherche sur la nutrition et le métabolisme, Montfort Hospital, University of Ottawa, Ottawa, Ontario, Canada.
Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Sébastien M. Labbé
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
Department of Medicine, Centre de recherche clinique Etienne-Le Bel, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Unité de recherche sur la nutrition et le métabolisme, Montfort Hospital, University of Ottawa, Ottawa, Ontario, Canada.
Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Denis P. Blondin
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
Department of Medicine, Centre de recherche clinique Etienne-Le Bel, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Unité de recherche sur la nutrition et le métabolisme, Montfort Hospital, University of Ottawa, Ottawa, Ontario, Canada.
Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Serge Phoenix
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
Department of Medicine, Centre de recherche clinique Etienne-Le Bel, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Unité de recherche sur la nutrition et le métabolisme, Montfort Hospital, University of Ottawa, Ottawa, Ontario, Canada.
Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Brigitte Guérin
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
Department of Medicine, Centre de recherche clinique Etienne-Le Bel, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Unité de recherche sur la nutrition et le métabolisme, Montfort Hospital, University of Ottawa, Ottawa, Ontario, Canada.
Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - François Haman
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
Department of Medicine, Centre de recherche clinique Etienne-Le Bel, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Unité de recherche sur la nutrition et le métabolisme, Montfort Hospital, University of Ottawa, Ottawa, Ontario, Canada.
Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Eric E. Turcotte
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
Department of Medicine, Centre de recherche clinique Etienne-Le Bel, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Unité de recherche sur la nutrition et le métabolisme, Montfort Hospital, University of Ottawa, Ottawa, Ontario, Canada.
Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Denis Richard
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
Department of Medicine, Centre de recherche clinique Etienne-Le Bel, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Unité de recherche sur la nutrition et le métabolisme, Montfort Hospital, University of Ottawa, Ottawa, Ontario, Canada.
Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - André C. Carpentier
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
Department of Medicine, Centre de recherche clinique Etienne-Le Bel, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Unité de recherche sur la nutrition et le métabolisme, Montfort Hospital, University of Ottawa, Ottawa, Ontario, Canada.
Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Postprandial metabolism of meal triglyceride in humans. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:721-6. [PMID: 22281699 DOI: 10.1016/j.bbalip.2012.01.006] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 01/05/2012] [Accepted: 01/06/2012] [Indexed: 12/20/2022]
Abstract
The intake of dietary fat above energy needs has contributed to the growing rates of obesity worldwide. The concept of disease development occurring in the fed state now has much support and dysregulation of substrate flux may occur due to poor handling of dietary fat in the immediate postprandial period. The present paper will review recent observations implicating cephalic phase events in the control of enterocyte lipid transport, the impact of varying the composition of meals on subsequent fat metabolism, and the means by which dietary lipid carried in chylomicrons can lead to elevated postprandial non-esterified fatty acid concentrations. This discussion is followed by an evaluation of the data on quantitative meal fat oxidation at the whole body level and an examination of dietary fat clearance to peripheral tissues - with particular attention paid to skeletal muscle and liver given the role of ectopic lipid deposition in insulin resistance. Estimates derived from data of dietary-TG clearance show good agreement with clearance to the liver equaling 8-12% of meal fat in lean subjects and this number appears higher (10-16%) in subjects with diabetes and fatty liver disease. Finally, we discuss new methods with which to study dietary fatty acid partitioning in vivo. Future research is needed to include a more comprehensive understanding of 1) the potential for differential oxidation of saturated versus unsaturated fatty acids which might lead to meaningful energy deficit and whether this parameter varies based on insulin sensitivity, 2) whether compartmentalization exists for diet-derived fatty acids within tissues vs. intracellular pools, and 3) the role of reduced peripheral fatty acid clearance in the development of fatty liver disease. Further advancements in the quantitation of dietary fat absorption and disposal will be central to the development of therapies designed to treat diet-induced obesity. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.
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Richard D, Monge-Roffarello B, Chechi K, Labbé SM, Turcotte EE. Control and physiological determinants of sympathetically mediated brown adipose tissue thermogenesis. Front Endocrinol (Lausanne) 2012; 3:36. [PMID: 22654862 PMCID: PMC3356074 DOI: 10.3389/fendo.2012.00036] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Accepted: 02/13/2012] [Indexed: 02/05/2023] Open
Abstract
Brown adipose tissue (BAT) represents a remarkable heat-producing tissue. The thermogenic potential of BAT is conferred by uncoupling protein 1, a protein found uniquely in brown adipocytes. BAT activity and capacity is controlled by the sympathetic nervous system (SNS), which densely innervates brown fat depots. SNS-mediated BAT thermogenesis is essentially governed by hypothalamic and brainstem neurons. BAT activity is also modulated by brain energy balance pathways including the very significant brain melanocortin system, suggesting a genuine involvement of SNS-mediated BAT thermogenesis in energy homeostasis. The use of positron emission tomography/computed tomography scanning has revealed the presence of well-defined BAT depots in the cervical, clavicular, and paraspinal areas in adult humans. The prevalence of these depots is higher in subjects exposed to low temperature and is also higher in women compared to men. Moreover, the prevalence of BAT decreases with age and body fat mass, suggesting that BAT could be involved in energy balance regulation and obesity in humans. This short review summarizes recent progress made in our understanding of the control of SNS-mediated BAT thermogenesis and of the determinants of BAT prevalence or detection in humans.
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Affiliation(s)
- Denis Richard
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec et Groupe interdisciplinaire de Recherche sur l’Obésité de l’Université LavalQuébec, QC, Canada
- *Correspondence: Denis Richard, Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, 2725 Chemin Sainte-Foy, Québec, QC, Canada G1V 4G5. e-mail:
| | - Boris Monge-Roffarello
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec et Groupe interdisciplinaire de Recherche sur l’Obésité de l’Université LavalQuébec, QC, Canada
| | - Kanta Chechi
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec et Groupe interdisciplinaire de Recherche sur l’Obésité de l’Université LavalQuébec, QC, Canada
| | - Sébastien M. Labbé
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec et Groupe interdisciplinaire de Recherche sur l’Obésité de l’Université LavalQuébec, QC, Canada
| | - Eric E. Turcotte
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec et Groupe interdisciplinaire de Recherche sur l’Obésité de l’Université LavalQuébec, QC, Canada
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Carpentier AC, Labbé SM, Grenier-Larouche T, Noll C. Abnormal dietary fatty acid metabolic partitioning in insulin resistance and Type 2 diabetes. ACTA ACUST UNITED AC 2011. [DOI: 10.2217/clp.11.60] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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