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Natali A, Nesti L. Vascular effects of insulin. Metabolism 2021; 124:154891. [PMID: 34563557 DOI: 10.1016/j.metabol.2021.154891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/13/2021] [Accepted: 09/20/2021] [Indexed: 10/20/2022]
Affiliation(s)
- Andrea Natali
- Metabolism, Nutrition and Atherosclerosis Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Italy.
| | - Lorenzo Nesti
- Metabolism, Nutrition and Atherosclerosis Laboratory, Department of Clinical and Experimental Medicine, University of Pisa, Italy
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Love KM, Barrett EJ, Malin SK, Reusch JEB, Regensteiner JG, Liu Z. Diabetes pathogenesis and management: the endothelium comes of age. J Mol Cell Biol 2021; 13:500-512. [PMID: 33787922 PMCID: PMC8530521 DOI: 10.1093/jmcb/mjab024] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/10/2021] [Accepted: 02/25/2021] [Indexed: 12/03/2022] Open
Abstract
Endothelium, acting as a barrier, protects tissues against factors that provoke insulin resistance and type 2 diabetes and itself responds to the insult of insulin resistance inducers with altered function. Endothelial insulin resistance and vascular dysfunction occur early in the evolution of insulin resistance-related disease, can co-exist with and even contribute to the development of metabolic insulin resistance, and promote vascular complications in those affected. The impact of endothelial insulin resistance and vascular dysfunction varies depending on the blood vessel size and location, resulting in decreased arterial plasticity, increased atherosclerosis and vascular resistance, and decreased tissue perfusion. Women with insulin resistance and diabetes are disproportionately impacted by cardiovascular disease, likely related to differential sex-hormone endothelium effects. Thus, reducing endothelial insulin resistance and improving endothelial function in the conduit arteries may reduce atherosclerotic complications, in the resistance arteries lead to better blood pressure control, and in the microvasculature lead to less microvascular complications and more effective tissue perfusion. Multiple diabetes therapeutic modalities, including medications and exercise training, improve endothelial insulin action and vascular function. This action may delay the onset of type 2 diabetes and/or its complications, making the vascular endothelium an attractive therapeutic target for type 2 diabetes and potentially type 1 diabetes.
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MESH Headings
- Age Factors
- Cardiovascular Diseases/epidemiology
- Cardiovascular Diseases/ethnology
- Cardiovascular Diseases/metabolism
- Cardiovascular Diseases/physiopathology
- Comorbidity
- Diabetes Mellitus, Type 1/drug therapy
- Diabetes Mellitus, Type 1/epidemiology
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/physiopathology
- Diabetes Mellitus, Type 2/drug therapy
- Diabetes Mellitus, Type 2/epidemiology
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/physiopathology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/physiopathology
- Exercise
- Female
- Humans
- Hypoglycemic Agents/pharmacology
- Hypoglycemic Agents/therapeutic use
- Insulin Resistance
- Male
- Racial Groups
- Risk Factors
- Sex Factors
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Affiliation(s)
- Kaitlin M Love
- Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Eugene J Barrett
- Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Steven K Malin
- Department of Kinesiology and Health, Rutgers University, New Brunswick, NJ, USA
- Division of Endocrinology, Metabolism and Nutrition, Rutgers University, New Brunswick, NJ, USA
- New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, NJ, USA
- Institute of Translational Medicine and Research, Rutgers University, New Brunswick, NJ, USA
| | - Jane E B Reusch
- Center for Women’s Health Research, University of Colorado School of Medicine, Aurora, CO, USA
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
- Rocky Mountain Regional Veterans Affairs Medical Center, Aurora, CO, USA
| | - Judith G Regensteiner
- Center for Women’s Health Research, University of Colorado School of Medicine, Aurora, CO, USA
- Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Zhenqi Liu
- Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
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Carpentier AC. 100 th anniversary of the discovery of insulin perspective: insulin and adipose tissue fatty acid metabolism. Am J Physiol Endocrinol Metab 2021; 320:E653-E670. [PMID: 33522398 DOI: 10.1152/ajpendo.00620.2020] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Insulin inhibits systemic nonesterified fatty acid (NEFA) flux to a greater degree than glucose or any other metabolite. This remarkable effect is mainly due to insulin-mediated inhibition of intracellular triglyceride (TG) lipolysis in adipose tissues and is essential to prevent diabetic ketoacidosis, but also to limit the potential lipotoxic effects of NEFA in lean tissues that contribute to the development of diabetes complications. Insulin also regulates adipose tissue fatty acid esterification, glycerol and TG synthesis, lipogenesis, and possibly oxidation, contributing to the trapping of dietary fatty acids in the postprandial state. Excess NEFA flux at a given insulin level has been used to define in vivo adipose tissue insulin resistance. Adipose tissue insulin resistance defined in this fashion has been associated with several dysmetabolic features and complications of diabetes, but the mechanistic significance of this concept is not fully understood. This review focusses on the in vivo regulation of adipose tissue fatty acid metabolism by insulin and the mechanistic significance of the current definition of adipose tissue insulin resistance. One hundred years after the discovery of insulin and despite decades of investigations, much is still to be understood about the multifaceted in vivo actions of this hormone on adipose tissue fatty acid metabolism.
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Affiliation(s)
- André C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Gradel AKJ, Kildegaard J, Porsgaard T, Lykkesfeldt J, Refsgaard HHF. Food intake rather than blood glucose levels affects the pharmacokinetic profile of insulin aspart in pigs. Basic Clin Pharmacol Toxicol 2021; 128:783-794. [PMID: 33626236 DOI: 10.1111/bcpt.13574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 01/26/2021] [Accepted: 02/22/2021] [Indexed: 12/29/2022]
Abstract
In humans, food intake and glucose infusion have been reported to increase subcutaneous blood flow. Since local blood flow influences the rate of insulin absorption from the subcutaneous tissue, we hypothesised that an increase in blood glucose levels-occurring as the result of glucose infusion or food intake-could modulate the pharmacokinetic properties of subcutaneously administered insulin. The pharmacokinetic profile of insulin aspart was assessed in 29 domestic pigs that were examined in a fed and fasted state or included in hyperinsulinaemic clamp studies of 4 vs. 10 mmol/L glucose prior to subcutaneous (30 nmol) or intravenous (0.1 nmol/kg) insulin administration. Results showed that food intake compared to fasting accelerated absorption and decreased clearance of insulin aspart (P < 0.05). Furthermore, higher c-peptide but also glucagon levels were observed in fed compared to fasted pigs (P < 0.05). The pharmacokinetic profile of insulin aspart did not differ between pigs clamped at 4 vs. 10 mmol/L glucose. Hence, food intake rather than blood glucose levels within normal range modulates the pharmacokinetic properties of insulin aspart upon subcutaneous and intravenous administration in pigs.
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Affiliation(s)
- Anna Katrina Jógvansdóttir Gradel
- Section for Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Frederiksberg, Copenhagen, Denmark.,Global Drug Discovery, Novo Nordisk A/S, Måløv, Denmark
| | | | | | - Jens Lykkesfeldt
- Section for Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Frederiksberg, Copenhagen, Denmark
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Sabaratnam R, Svenningsen P. Adipocyte-Endothelium Crosstalk in Obesity. Front Endocrinol (Lausanne) 2021; 12:681290. [PMID: 34456860 PMCID: PMC8387580 DOI: 10.3389/fendo.2021.681290] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/22/2021] [Indexed: 12/19/2022] Open
Abstract
Obesity is characterized by pathological adipose tissue (AT) expansion. While healthy AT expansion enhances systemic insulin sensitivity, unhealthy AT expansion through increased adipocyte size is associated with insulin resistance, fibrosis, hypoxia, and reduced adipose-derived adiponectin secretion. The mechanisms causing the unhealthy AT expansion are not fully elucidated; yet, dysregulated crosstalk between cells within the AT is an important contributor. Evidence from animal and human studies suggests a crucial role of the crosstalk between vascular endothelium (the innermost cell type in blood vessels) and adipocytes for metabolic homeostasis. Arterial endothelial cells are directly involved in maintaining normal organ functions through local blood flow regulation. The endothelial-dependent regulation of blood flow in AT is hampered in obesity, which negatively affects the adipocyte. Moreover, endothelial cells secrete extracellular vesicles (EVs) that target adipocytes in vivo. The endothelial EVs secretion is hampered in obesity and may be affected by the adipocyte-derived adipokine adiponectin. Adiponectin targets the vascular endothelium, eliciting organ-protective functions through binding to T-cadherin. The reduced obesity-induced adiponectin binding of T-cadherin reduces endothelial EV secretion. This affects endothelial health and cell-cell communication between AT cells and distant organs, influencing systemic energy homeostasis. This review focuses on the current understanding of endothelial and adipocyte crosstalk. We will discuss how obesity changes the AT environment and how these changes contribute to obesity-associated metabolic disease in humans. Particularly, we will describe and discuss the EV-dependent communication and regulation between adipocytes, adiponectin, and the endothelial cells regulating systemic energy homeostasis in health and metabolic disease in humans.
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Affiliation(s)
- Rugivan Sabaratnam
- Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
- Section of Molecular Diabetes and Metabolism, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
- Department of Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
| | - Per Svenningsen
- Department of Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
- *Correspondence: Per Svenningsen,
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Samms RJ, Coghlan MP, Sloop KW. How May GIP Enhance the Therapeutic Efficacy of GLP-1? Trends Endocrinol Metab 2020; 31:410-421. [PMID: 32396843 DOI: 10.1016/j.tem.2020.02.006] [Citation(s) in RCA: 181] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/30/2020] [Accepted: 02/06/2020] [Indexed: 12/25/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) receptor agonists improve glucose homeostasis, reduce bodyweight, and over time benefit cardiovascular health in type 2 diabetes mellitus (T2DM). However, dose-related gastrointestinal effects limit efficacy, and therefore agents possessing GLP-1 pharmacology that can also target alternative pathways may expand the therapeutic index. One approach is to engineer GLP-1 activity into the sequence of glucose-dependent insulinotropic polypeptide (GIP). Although the therapeutic implications of the lipogenic actions of GIP are debated, its ability to improve lipid and glucose metabolism is especially evident when paired with the anorexigenic mechanism of GLP-1. We review the complexity of GIP in regulating adipose tissue function and energy balance in the context of recent findings in T2DM showing that dual GIP/GLP-1 receptor agonist therapy produces profound weight loss, glycemic control, and lipid lowering.
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Affiliation(s)
- Ricardo J Samms
- Diabetes and Complications, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
| | - Matthew P Coghlan
- Diabetes and Complications, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
| | - Kyle W Sloop
- Diabetes and Complications, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA.
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Emanuel AL, Meijer RI, Woerdeman J, van Raalte DH, Diamant M, Kramer MHH, Serlie MJ, Eringa EC, Serné EH. Effects of a Hypercaloric and Hypocaloric Diet on Insulin-Induced Microvascular Recruitment, Glucose Uptake, and Lipolysis in Healthy Lean Men. Arterioscler Thromb Vasc Biol 2020; 40:1695-1704. [PMID: 32404008 DOI: 10.1161/atvbaha.120.314129] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
OBJECTIVE In mice fed a high-fat diet, impairment of insulin signaling in endothelium is an early phenomenon that precedes decreased insulin sensitivity of skeletal muscle, adipose tissue, and liver. We assessed in humans whether short-term overfeeding affects insulin-induced microvascular recruitment in skeletal muscle and adipose tissue before changes occur in glucose uptake and lipolysis. Approach and Results: Fifteen healthy males underwent a hypercaloric and subsequent hypocaloric diet intervention. Before, during, and after the hypercaloric diet, and upon return to baseline weight, all participants underwent (1) a hyperinsulinemic-euglycemic clamp to determine insulin-induced glucose uptake and suppression of lipolysis (2) contrast-enhanced ultrasonography to measure insulin-induced microvascular recruitment in skeletal muscle and adipose tissue. In addition, we assessed insulin-induced vasodilation of isolated skeletal muscle resistance arteries by pressure myography after the hypercaloric diet in study participants and controls (n=5). The hypercaloric diet increased body weight (3.5 kg; P<0.001) and fat percentage (3.5%; P<0.001) but did not affect glucose uptake nor lipolysis. The hypercaloric diet increased adipose tissue microvascular recruitment (P=0.041) and decreased the ratio between skeletal muscle and adipose tissue microvascular blood volume during hyperinsulinemia (P=0.019). Insulin-induced vasodilation of isolated skeletal muscle arterioles was significantly lower in participants compared with controls (P<0.001). The hypocaloric diet reversed all of these changes, except the increase in adipose tissue microvascular recruitment. CONCLUSIONS In lean men, short-term overfeeding reduces insulin-induced vasodilation of skeletal muscle resistance arteries and shifts the distribution of tissue perfusion during hyperinsulinemia from skeletal muscle to adipose tissue without affecting glucose uptake and lipolysis. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02628301.
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Affiliation(s)
- Anna L Emanuel
- From the Department of Internal Medicine (A.L.E., R.I.M., J.W., D.H.v.R., M.D., M.H.H.K., E.H.S.), Amsterdam UMC, location VU University Medical Center, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Rick I Meijer
- From the Department of Internal Medicine (A.L.E., R.I.M., J.W., D.H.v.R., M.D., M.H.H.K., E.H.S.), Amsterdam UMC, location VU University Medical Center, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Jorn Woerdeman
- From the Department of Internal Medicine (A.L.E., R.I.M., J.W., D.H.v.R., M.D., M.H.H.K., E.H.S.), Amsterdam UMC, location VU University Medical Center, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Daniel H van Raalte
- From the Department of Internal Medicine (A.L.E., R.I.M., J.W., D.H.v.R., M.D., M.H.H.K., E.H.S.), Amsterdam UMC, location VU University Medical Center, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Michaela Diamant
- From the Department of Internal Medicine (A.L.E., R.I.M., J.W., D.H.v.R., M.D., M.H.H.K., E.H.S.), Amsterdam UMC, location VU University Medical Center, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Mark H H Kramer
- From the Department of Internal Medicine (A.L.E., R.I.M., J.W., D.H.v.R., M.D., M.H.H.K., E.H.S.), Amsterdam UMC, location VU University Medical Center, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Mireille J Serlie
- Department of Endocrinology and Metabolism, Amsterdam UMC, location Academic Medical Center, Amsterdam, The Netherlands (M.J.S.)
| | - Etto C Eringa
- Department of Physiology (E.C.E.), Amsterdam UMC, location VU University Medical Center, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands.,Department of Physiology, Maastricht University, Maastricht, The Netherlands (E.C.E.)
| | - Erik H Serné
- From the Department of Internal Medicine (A.L.E., R.I.M., J.W., D.H.v.R., M.D., M.H.H.K., E.H.S.), Amsterdam UMC, location VU University Medical Center, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
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Hu D, Remash D, Russell RD, Greenaway T, Rattigan S, Squibb KA, Jones G, Premilovac D, Richards SM, Keske MA. Impairments in Adipose Tissue Microcirculation in Type 2 Diabetes Mellitus Assessed by Real-Time Contrast-Enhanced Ultrasound. Circ Cardiovasc Imaging 2019; 11:e007074. [PMID: 29650791 DOI: 10.1161/circimaging.117.007074] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 02/22/2018] [Indexed: 01/07/2023]
Abstract
BACKGROUND In obesity and type 2 diabetes mellitus (T2D), adipose tissue expansion (because of larger adipocytes) results in reduced microvascular density which is thought to lead to adipocyte hypoxia, inflammation, and reduced nutrient delivery to the adipocyte. Adipose tissue microvascular responses in humans with T2D have not been extensively characterized. Furthermore, it has not been determined whether impaired microvascular responses in human adipose tissue are most closely associated with adiposity, inflammation, or altered metabolism. METHODS AND RESULTS Overnight-fasted healthy controls (n=24, 9 females/15 males) and people with T2D (n=21, 8 females/13 males) underwent a body composition scan (dual-energy X-ray absorptiometry), an oral glucose challenge (50 g glucose) and blood analysis of clinical chemistries and inflammatory markers. Abdominal subcutaneous adipose tissue microvascular responses were measured by contrast-enhanced ultrasound at baseline and 1-hour post-oral glucose challenge. Adipose tissue microvascular blood volume was significantly elevated in healthy subjects 1-hour post-oral glucose challenge; however, this effect was absent in T2D. Adipose tissue microvascular blood flow was lower in people with T2D at baseline and was significantly blunted post-oral glucose challenge compared with controls. Adipose tissue microvascular blood flow was negatively associated with truncal fat (%), glucoregulatory function, fasting triglyceride and nonesterified fatty acid levels, and positively associated with insulin sensitivity. Truncal fat (%), systolic blood pressure, and insulin sensitivity were the only correlates with microvascular blood volume. Systemic inflammation was not associated with adipose tissue microvascular responses. CONCLUSIONS Impaired microvascular function in adipose tissue during T2D is not conditionally linked to systemic inflammation but is associated with other characteristics of the metabolic syndrome (obesity, insulin resistance, hyperglycemia, and dyslipidemia).
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Affiliation(s)
- Donghua Hu
- Menzies Institute for Medical Research (D.H., R.D.R., S.R., K.A.S., G.J., S.M.R., M.A.K.) and School of Medicine (D.R., T.G., D.P., S.M.R.), University of Tasmania, Hobart, TAS Australia; Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley, Brownsville TX, (R.D.R.); Royal Hobart Hospital, TAS, Australia (T.G.); Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia (M.A.K.); and Department of Pharmacology, Anhui Medical University, Hefei, China (D.H.)
| | - Devika Remash
- Menzies Institute for Medical Research (D.H., R.D.R., S.R., K.A.S., G.J., S.M.R., M.A.K.) and School of Medicine (D.R., T.G., D.P., S.M.R.), University of Tasmania, Hobart, TAS Australia; Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley, Brownsville TX, (R.D.R.); Royal Hobart Hospital, TAS, Australia (T.G.); Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia (M.A.K.); and Department of Pharmacology, Anhui Medical University, Hefei, China (D.H.)
| | - Ryan D Russell
- Menzies Institute for Medical Research (D.H., R.D.R., S.R., K.A.S., G.J., S.M.R., M.A.K.) and School of Medicine (D.R., T.G., D.P., S.M.R.), University of Tasmania, Hobart, TAS Australia; Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley, Brownsville TX, (R.D.R.); Royal Hobart Hospital, TAS, Australia (T.G.); Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia (M.A.K.); and Department of Pharmacology, Anhui Medical University, Hefei, China (D.H.)
| | - Timothy Greenaway
- Menzies Institute for Medical Research (D.H., R.D.R., S.R., K.A.S., G.J., S.M.R., M.A.K.) and School of Medicine (D.R., T.G., D.P., S.M.R.), University of Tasmania, Hobart, TAS Australia; Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley, Brownsville TX, (R.D.R.); Royal Hobart Hospital, TAS, Australia (T.G.); Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia (M.A.K.); and Department of Pharmacology, Anhui Medical University, Hefei, China (D.H.)
| | - Stephen Rattigan
- Menzies Institute for Medical Research (D.H., R.D.R., S.R., K.A.S., G.J., S.M.R., M.A.K.) and School of Medicine (D.R., T.G., D.P., S.M.R.), University of Tasmania, Hobart, TAS Australia; Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley, Brownsville TX, (R.D.R.); Royal Hobart Hospital, TAS, Australia (T.G.); Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia (M.A.K.); and Department of Pharmacology, Anhui Medical University, Hefei, China (D.H.)
| | - Kathryn A Squibb
- Menzies Institute for Medical Research (D.H., R.D.R., S.R., K.A.S., G.J., S.M.R., M.A.K.) and School of Medicine (D.R., T.G., D.P., S.M.R.), University of Tasmania, Hobart, TAS Australia; Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley, Brownsville TX, (R.D.R.); Royal Hobart Hospital, TAS, Australia (T.G.); Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia (M.A.K.); and Department of Pharmacology, Anhui Medical University, Hefei, China (D.H.)
| | - Graeme Jones
- Menzies Institute for Medical Research (D.H., R.D.R., S.R., K.A.S., G.J., S.M.R., M.A.K.) and School of Medicine (D.R., T.G., D.P., S.M.R.), University of Tasmania, Hobart, TAS Australia; Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley, Brownsville TX, (R.D.R.); Royal Hobart Hospital, TAS, Australia (T.G.); Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia (M.A.K.); and Department of Pharmacology, Anhui Medical University, Hefei, China (D.H.)
| | - Dino Premilovac
- Menzies Institute for Medical Research (D.H., R.D.R., S.R., K.A.S., G.J., S.M.R., M.A.K.) and School of Medicine (D.R., T.G., D.P., S.M.R.), University of Tasmania, Hobart, TAS Australia; Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley, Brownsville TX, (R.D.R.); Royal Hobart Hospital, TAS, Australia (T.G.); Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia (M.A.K.); and Department of Pharmacology, Anhui Medical University, Hefei, China (D.H.)
| | - Stephen M Richards
- Menzies Institute for Medical Research (D.H., R.D.R., S.R., K.A.S., G.J., S.M.R., M.A.K.) and School of Medicine (D.R., T.G., D.P., S.M.R.), University of Tasmania, Hobart, TAS Australia; Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley, Brownsville TX, (R.D.R.); Royal Hobart Hospital, TAS, Australia (T.G.); Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia (M.A.K.); and Department of Pharmacology, Anhui Medical University, Hefei, China (D.H.)
| | - Michelle A Keske
- Menzies Institute for Medical Research (D.H., R.D.R., S.R., K.A.S., G.J., S.M.R., M.A.K.) and School of Medicine (D.R., T.G., D.P., S.M.R.), University of Tasmania, Hobart, TAS Australia; Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley, Brownsville TX, (R.D.R.); Royal Hobart Hospital, TAS, Australia (T.G.); Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia (M.A.K.); and Department of Pharmacology, Anhui Medical University, Hefei, China (D.H.).
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9
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Affiliation(s)
- Jonathan R Lindner
- Knight Cardiovascular Institute and the Oregon National Primate Research Center, Oregon Health & Science University, Portland, OR.
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10
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Ferrannini E, Iozzo P, Virtanen KA, Honka MJ, Bucci M, Nuutila P. Adipose tissue and skeletal muscle insulin-mediated glucose uptake in insulin resistance: role of blood flow and diabetes. Am J Clin Nutr 2018; 108:749-758. [PMID: 30239554 DOI: 10.1093/ajcn/nqy162] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/14/2018] [Indexed: 12/14/2022] Open
Abstract
Background Adipose tissue glucose uptake is impaired in insulin-resistant states, but ex vivo studies of human adipose tissue have yielded heterogeneous results. This discrepancy may be due to different regulation of blood supply. Objective The aim of this study was to test the flow dependency of in vivo insulin-mediated glucose uptake in fat tissues, and to contrast it with that of skeletal muscle. Design We reanalyzed data from 159 individuals in which adipose tissue depots-subcutaneous abdominal and femoral, and intraperitoneal-and femoral skeletal muscle were identified by MRI, and insulin-stimulated glucose uptake ([18F]-fluoro-2-deoxyglucose) and blood flow ([15O]-H2O) were measured simultaneously by positron emission tomography scanning. Results Individuals in the bottom tertile of whole-body glucose uptake [median (IQR) 36 (17) µmol. kg fat-free mass (kgFFM)-1 . min-1 .nM-1] displayed all features of insulin resistance compared with the rest of the group [median (IQR) 97 (71) µmol . kgFFM-1 .min-1 . nM-1]. Rates of glucose uptake were directly related to the degree of insulin resistance in all fat depots as well as in skeletal muscle. However, blood flow was inversely related to insulin sensitivity in each fat depot (all P ≤ 0.03), whereas femoral muscle blood flow was not significantly different between insulin-resistant and insulin-sensitive subjects, and was not related to insulin sensitivity. Furthermore, in subjects performing one-leg exercise, blood flow increased 5- to 6-fold in femoral muscle but not in the overlying adipose tissue. The presence of diabetes was associated with a modest increase in fat and muscle glucose uptake independent of insulin resistance. Conclusions Reduced blood supply is an important factor for the impairment of in vivo insulin-mediated glucose uptake in both subcutaneous and visceral fat. In contrast, the insulin resistance of glucose uptake in resting skeletal muscle is predominantly a cellular defect. Diabetes provides a modest compensatory increase in fat and muscle glucose uptake that is independent of insulin resistance.
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Affiliation(s)
- Ele Ferrannini
- Institute of Clinical Physiology, National Research Council, Pisa, Italy
| | - Patricia Iozzo
- Institute of Clinical Physiology, National Research Council, Pisa, Italy.,Turku PET Centre, University of Turku, Turku, Finland
| | | | | | - Marco Bucci
- Turku PET Centre, University of Turku, Turku, Finland
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku, Turku, Finland.,Department of Endocrinology, Turku University Hospital, Turku, Finland
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Asmar A, Asmar M, Simonsen L, Madsbad S, Holst JJ, Hartmann B, Sorensen CM, Bülow J. Glucagon-like peptide-1 elicits vasodilation in adipose tissue and skeletal muscle in healthy men. Physiol Rep 2018; 5:5/3/e13073. [PMID: 28174344 PMCID: PMC5309569 DOI: 10.14814/phy2.13073] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 11/03/2016] [Accepted: 11/13/2016] [Indexed: 12/24/2022] Open
Abstract
In healthy subjects, we recently demonstrated that during acute administration of GLP-1, cardiac output increased significantly, whereas renal blood flow remained constant. We therefore hypothesize that GLP-1 induces vasodilation in other organs, for example, adipose tissue, skeletal muscle, and/or splanchnic tissues. Nine healthy men were examined twice in random order during a 2-hour infusion of either GLP-1 (1.5 pmol kg-1 min-1) or saline. Cardiac output was continuously estimated noninvasively concomitantly with measurement of intra-arterial blood pressure. Subcutaneous, abdominal adipose tissue blood flow (ATBF) was measured by the 133Xenon clearance technique. Leg and splanchnic blood flow were measured by Fick's Principle, using indocyanine green as indicator. In the GLP-1 study, cardiac output increased significantly together with a significant increase in arterial pulse pressure and heart rate compared with the saline study. Subcutaneous, abdominal ATBF and leg blood flow increased significantly during the GLP-1 infusion compared with saline, whereas splanchnic blood flow response did not differ between the studies. We conclude that in healthy subjects, GLP-1 increases cardiac output acutely due to a GLP-1-induced vasodilation in adipose tissue and skeletal muscle together with an increase in cardiac work.
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Affiliation(s)
- Ali Asmar
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital, Copenhagen, Denmark
| | - Meena Asmar
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital, Copenhagen, Denmark
| | - Lene Simonsen
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital, Copenhagen, Denmark
| | - Sten Madsbad
- Department of Endocrinology, Hvidovre University Hospital, Copenhagen, Denmark
| | - Jens J Holst
- NNF Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bolette Hartmann
- NNF Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Charlotte M Sorensen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Bülow
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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Sun L, Yan J, Sun L, Velan S, Leow M. A synopsis of brown adipose tissue imaging modalities for clinical research. DIABETES & METABOLISM 2017; 43:401-410. [DOI: 10.1016/j.diabet.2017.03.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 03/02/2017] [Accepted: 03/27/2017] [Indexed: 12/20/2022]
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Manolopoulos KN, O'Reilly MW, Bujalska IJ, Tomlinson JW, Arlt W. Acute Hypercortisolemia Exerts Depot-Specific Effects on Abdominal and Femoral Adipose Tissue Function. J Clin Endocrinol Metab 2017; 102:1091-1101. [PMID: 28323916 PMCID: PMC5460725 DOI: 10.1210/jc.2016-3600] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 02/13/2017] [Indexed: 01/20/2023]
Abstract
CONTEXT Glucocorticoids have pleiotropic metabolic functions, and acute glucocorticoid excess affects fatty acid metabolism, increasing systemic lipolysis. Whether glucocorticoids exert adipose tissue depot-specific effects remains unclear. OBJECTIVE To provide an in vivo assessment of femoral and abdominal adipose tissue responses to acute glucocorticoid administration. DESIGN AND OUTCOME MEASURES Nine healthy male volunteers were studied on two occasions, after a hydrocortisone infusion (0.2 mg/kg/min for 14 hours) and a saline infusion, respectively, given in randomized double-blind order. The subjects were studied in the fasting state and after a 75-g glucose drink with an in vivo assessment of femoral adipose tissue blood flow (ATBF) using radioactive xenon washout and of lipolysis and glucose uptake using the arteriovenous difference technique. In a separate study (same infusion design), eight additional healthy male subjects underwent assessment of fasting abdominal ATBF and lipolysis only. Lipolysis was assessed as the net release of nonesterified fatty acids (NEFAs) from femoral and abdominal subcutaneous adipose tissue. RESULTS Acute hypercortisolemia significantly increased basal and postprandial ATBF in femoral adipose tissue, but the femoral net NEFA release did not change. In abdominal adipose tissue, hypercortisolemia induced substantial increases in basal ATBF and NEFA release. CONCLUSIONS Acute hypercortisolemia induces differential lipolysis and ATBF responses in abdominal and femoral adipose tissue, suggesting depot-specific glucocorticoid effects. Abdominal, but not femoral, adipose tissue contributes to the hypercortisolemia-induced systemic NEFA increase, with likely contributions from other adipose tissue sources and intravascular triglyceride hydrolysis.
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Affiliation(s)
- Konstantinos N Manolopoulos
- Institute of Metabolism and Systems Research, University of Birmingham B15 2TT, United Kingdom
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TH, United Kingdom
| | - Michael W O'Reilly
- Institute of Metabolism and Systems Research, University of Birmingham B15 2TT, United Kingdom
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TH, United Kingdom
| | - Iwona J Bujalska
- Institute of Metabolism and Systems Research, University of Birmingham B15 2TT, United Kingdom
| | - Jeremy W Tomlinson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, National Institute for Health Research Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, United Kingdom
| | - Wiebke Arlt
- Institute of Metabolism and Systems Research, University of Birmingham B15 2TT, United Kingdom
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TH, United Kingdom
- National Institute for Health Research Birmingham Liver Biomedical Research Unit, University Hospitals Birmingham, National Health Service Foundation Trust, Birmingham B15 2TH, United Kingdom
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Schumann U, Jenkinson CP, Alt A, Zügel M, Steinacker JM, Flechtner-Mors M. Sympathetic nervous system activity and anti-lipolytic response to iv-glucose load in subcutaneous adipose tissue of obese and obese type 2 diabetic subjects. PLoS One 2017; 12:e0173803. [PMID: 28346464 PMCID: PMC5367786 DOI: 10.1371/journal.pone.0173803] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 02/16/2017] [Indexed: 01/25/2023] Open
Abstract
The study aim was to investigate the effect of endogenous insulin release on lipolysis in subcutaneous adipose tissue after adrenergic stimulation in obese subjects diagnosed with type 2 diabetes (T2D). In 14 obese female T2D subjects, or 14 obese non-T2D controls, glycerol concentration was measured in response to the α1,2,ß-agonist norepinephrine, the α1-agonist norfenefrine and the ß2-agonist terbutaline (each 10-4 M), using the microdialysis technique. After 60 minutes of stimulation, an intravenous glucose load (0.5 g/kg lean body mass) was given. Local blood flow was monitored by means of the ethanol technique. Norepinephrine and norfenefrine induced a four and three fold rise in glycerol dialysate concentration (p<0.001, each), with a similar pattern in adipose tissue. Following agonist stimulation and glucose infusion, endogenous insulin release inhibited lipolysis in the presence of norepinephrine, which was more rapid and pronounced in healthy obese controls than in T2D subjects (p = 0.024 obese vs T2D subjects). Insulin-induced inhibition of lipolysis in the presence of norfenefrine was similar in all study participants. In the presence of terbutaline the lipolysis rate increased two fold until the effect of endogenous insulin (p<0.001). A similar insulin-induced decrease in lipolysis was observed for each of the norfenefrine groups and the terbutaline groups, respectively. Adipose tissue blood flow remained unchanged after the iv-glucose load. Both norepinephrine and norfenefrine diminished blood flow slightly, but insulin reversed this response (p<0.001 over the entire time). Terbutaline alone and terbutaline plus increased endogenous insulin augmented local blood flow (p<0.001 over the entire time). In conclusion, a difference in insulin-induced inhibition of lipolysis was observed in obese T2D subjects compared to obese healthy controls following modulation of sympathetic nervous system activity and is assumed to be due to ß1-adrenoceptor mediated stimulation by norepinephrine.
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Affiliation(s)
- Uwe Schumann
- Division of Sports and Rehabilitation Medicine, Medical Center, University of Ulm, Ulm, Germany
| | - Christopher P. Jenkinson
- South Texas Diabetes and Obesity Institute, University of Texas Rio Grande Valley, Harlingen, Texas, United States of America
| | - Andreas Alt
- Institute of Legal Medicine, University of Ulm, Ulm, Germany
| | - Martina Zügel
- Division of Sports and Rehabilitation Medicine, Medical Center, University of Ulm, Ulm, Germany
| | - Jürgen M. Steinacker
- Division of Sports and Rehabilitation Medicine, Medical Center, University of Ulm, Ulm, Germany
| | - Marion Flechtner-Mors
- Division of Sports and Rehabilitation Medicine, Medical Center, University of Ulm, Ulm, Germany
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Emanuel AL, Meijer RI, Muskiet MHA, van Raalte DH, Eringa EC, Serné EH. Role of Insulin-Stimulated Adipose Tissue Perfusion in the Development of Whole-Body Insulin Resistance. Arterioscler Thromb Vasc Biol 2017; 37:411-418. [PMID: 28126826 DOI: 10.1161/atvbaha.116.308670] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 01/17/2017] [Indexed: 01/08/2023]
Abstract
After food ingestion, macronutrients are transported to and stored in the skeletal muscle and adipose tissue. They can be subsequently used as an energy source in times of energy deprivation. Uptake of these nutrients in myocytes and adipocytes depends largely on adequate tissue perfusion. Interestingly, insulin is able to dilate skeletal muscle arterioles, which facilitates the delivery of macronutrients and insulin itself to muscle tissue. Insulin-stimulated skeletal muscle perfusion is impaired in several insulin-resistant states and is believed to contribute to impaired skeletal muscle glucose uptake and consequently impaired whole-body glucose disposal. Insulin-resistant individuals also exhibit blunted postprandial adipose tissue perfusion. However, the relevance of this impairment to metabolic dysregulation is less clear. In this review, we provide an overview of adipose tissue perfusion in healthy and insulin-resistant individuals, its regulation among others by insulin, and the possible influences of impaired adipose tissue perfusion on whole-body insulin sensitivity. Finally, we propose a novel hypothesis that acute overfeeding impacts distribution of macronutrients by reducing skeletal muscle perfusion, while adipose tissue perfusion remains intact. VISUAL OVERVIEW An online visual overview is available for this article.
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Affiliation(s)
- Anna L Emanuel
- From the Departments of Internal Medicine (A.L.E., R.I.M., M.H.A.M., D.H.v.R., E.H.S.) and Physiology (E.C.E.), VU University Medical Center, Amsterdam.
| | - Rick I Meijer
- From the Departments of Internal Medicine (A.L.E., R.I.M., M.H.A.M., D.H.v.R., E.H.S.) and Physiology (E.C.E.), VU University Medical Center, Amsterdam
| | - Marcel H A Muskiet
- From the Departments of Internal Medicine (A.L.E., R.I.M., M.H.A.M., D.H.v.R., E.H.S.) and Physiology (E.C.E.), VU University Medical Center, Amsterdam
| | - Daniël H van Raalte
- From the Departments of Internal Medicine (A.L.E., R.I.M., M.H.A.M., D.H.v.R., E.H.S.) and Physiology (E.C.E.), VU University Medical Center, Amsterdam
| | - Etto C Eringa
- From the Departments of Internal Medicine (A.L.E., R.I.M., M.H.A.M., D.H.v.R., E.H.S.) and Physiology (E.C.E.), VU University Medical Center, Amsterdam
| | - Erik H Serné
- From the Departments of Internal Medicine (A.L.E., R.I.M., M.H.A.M., D.H.v.R., E.H.S.) and Physiology (E.C.E.), VU University Medical Center, Amsterdam
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The blunted effect of glucose-dependent insulinotropic polypeptide in subcutaneous abdominal adipose tissue in obese subjects is partly reversed by weight loss. Nutr Diabetes 2016; 6:e208. [PMID: 27136446 PMCID: PMC4895376 DOI: 10.1038/nutd.2016.15] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/10/2016] [Accepted: 03/20/2016] [Indexed: 01/07/2023] Open
Abstract
Background: Glucose-dependent insulinotropic polypeptide (GIP) appears to have impaired effect on subcutaneous abdominal adipose tissue metabolism in obese subjects. The aim of the present study was to examine whether weight loss may reverse the impaired effect of GIP on subcutaneous abdominal adipose tissue in obese subjects. Methods: Five obese males participated in a 12-week weight loss program, which consisted of caloric restriction (800 Cal day−1) followed by 4 weeks of weight-maintenance diet. Before and after weight loss, subcutaneous adipose tissue lipid metabolism was studied by conducting regional measurements of arterio-venous plasma concentrations of metabolites and blood flow (adipose tissue blood flow, ATBF) across a segment of the abdominal adipose tissue in the fasting state and during GIP infusion (1.5 pmol kg−1 min−1) in combination with a hyperinsulinemic–hyperglycemic clamp. Results: After weight loss (7.5±0.8 kg), glucose tolerance and insulin sensitivity increased significantly as expected. No significant differences were seen in basal ATBF before (1.3±0.4 ml min−1 100 g tissue−1) and after weight loss (2.1±0.4 ml min−1 100 g tissue)−1; however, a tendency to increase was seen. After weight loss, GIP infusion increased ATBF significantly (3.2±0.1 ml min−1 100 g tissue−1) whereas there was no increase before weight loss. Triacylglycerol (TAG) uptake did not change after weight loss. Baseline free fatty acid (FFA) and glycerol output increased significantly after weight loss, P<0.001. During the clamp period, FFA and glycerol output declined significantly, P<0.05, with no differences before and after weight loss. Weight loss increased glucose uptake and decreased FFA/glycerol ratio during the clamp period, P<0.05. Conclusions: In obese subjects, weight loss, induced by calorie restriction, improves the blunted effect of GIP on subcutaneous abdominal adipose tissue metabolism.
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Sotorník R, Baillargeon JP, Gagnon-Auger M, Ménard J, Brassard P, Ardilouze JL. Regulation of blood flow in adipose tissue: involvement of the cholinergic system. Am J Physiol Endocrinol Metab 2015; 309:E55-62. [PMID: 25968573 DOI: 10.1152/ajpendo.00016.2015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 05/08/2015] [Indexed: 01/24/2023]
Abstract
Acetylcholine (Ach) has vasodilatory actions. However, data are conflicting about the role of Ach in regulating blood flow in subcutaneous adipose tissue (ATBF). This may be related to inaccurate ATBF recording or to the responder/nonresponder (R/NR) phenomenon. We showed previously that healthy individuals are R (ATBF increases postprandially by >50% of baseline BF) or NR (ATBF increases ≤50% postprandially). Our objective was to assess the role of the cholinergic system on ATBF in R and NR subjects. ATBF was manipulated by in situ microinfusion of vasoactive agents (VA) in AT and monitored by the (133)Xenon washout technique (both recognized methods) at the VA site and at the control site. We tested incrementally increasing doses of Ach (10(-5), 10(-3), and 10(-1) mol/l; n = 15) and Ach receptor antagonists (Ra) before and after oral administration of 75-g glucose using atropine (muscarinic Ra; 10(-4) mol/l, n = 13; 10(-5) mol/l, n = 22) and mecamylamine (nicotinic Ra; 10(-3) mol/l, n = 15; 10(-4) mol/l, n = 10). Compared with baseline [2.41 (1.36-2.83) ml·100 g(-1)·min(-1)], Ach increased ATBF dose dependently [3.32 (2.80-5.09), 6.46 (4.36-9.51), and 10.31 (7.98-11.52), P < 0.0001], with no difference between R and NR. Compared with control side, atropine (both concentrations) had no effect on fasting ATBF; only atropine 10(-4) mol/l decreased post-glucose ATBF [iAUC: 1.25 (0.32-2.91) vs. 1.98 (0.64-2.94); P = 0.04]. This effect was further apparent in R. Mecamylamine had no impact on fasting and postglucose ATBF in R and NR. Our results suggest that the cholinergic system is implicated in ATBF regulation, although it has no role in the blunting of ATBF response in NR.
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Affiliation(s)
- Richard Sotorník
- Department of Medicine, Division of Endocrinology, University Hospital Center of Sherbrooke, University of Sherbrooke, Sherbrooke, Quebec, Canada; and
| | - Jean-Patrice Baillargeon
- Department of Medicine, Division of Endocrinology, University Hospital Center of Sherbrooke, University of Sherbrooke, Sherbrooke, Quebec, Canada; and Clinical Research Center, University Hospital Center of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Maude Gagnon-Auger
- Department of Medicine, Division of Endocrinology, University Hospital Center of Sherbrooke, University of Sherbrooke, Sherbrooke, Quebec, Canada; and
| | - Julie Ménard
- Department of Medicine, Division of Endocrinology, University Hospital Center of Sherbrooke, University of Sherbrooke, Sherbrooke, Quebec, Canada; and Clinical Research Center, University Hospital Center of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Pascal Brassard
- Department of Medicine, Division of Endocrinology, University Hospital Center of Sherbrooke, University of Sherbrooke, Sherbrooke, Quebec, Canada; and Clinical Research Center, University Hospital Center of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Jean-Luc Ardilouze
- Department of Medicine, Division of Endocrinology, University Hospital Center of Sherbrooke, University of Sherbrooke, Sherbrooke, Quebec, Canada; and Clinical Research Center, University Hospital Center of Sherbrooke, Sherbrooke, Quebec, Canada
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18
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Arriarán S, Agnelli S, Remesar X, Fernández-López JA, Alemany M. The urea cycle of rat white adipose tissue. RSC Adv 2015. [DOI: 10.1039/c5ra16398f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
White adipose tissue urea-cycle enzymes showed a high activity and gene expression, second only to liver in catalytic capacity.
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Affiliation(s)
- Sofía Arriarán
- Department of Nutrition and Food Science
- Faculty of Biology
- University of Barcelona
- 08028 Barcelona
- Spain
| | - Silvia Agnelli
- Department of Nutrition and Food Science
- Faculty of Biology
- University of Barcelona
- 08028 Barcelona
- Spain
| | - Xavier Remesar
- Department of Nutrition and Food Science
- Faculty of Biology
- University of Barcelona
- 08028 Barcelona
- Spain
| | | | - Marià Alemany
- Department of Nutrition and Food Science
- Faculty of Biology
- University of Barcelona
- 08028 Barcelona
- Spain
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19
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Frayn KN, Karpe F. Regulation of human subcutaneous adipose tissue blood flow. Int J Obes (Lond) 2013; 38:1019-26. [PMID: 24166067 DOI: 10.1038/ijo.2013.200] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 09/12/2013] [Accepted: 09/21/2013] [Indexed: 12/14/2022]
Abstract
Subcutaneous adipose tissue represents about 85% of all body fat. Its major metabolic role is the regulated storage and mobilization of lipid energy. It stores lipid in the form of triacylglycerol (TG), which is mobilized, as required for use by other tissues, in the form of non-esterified fatty acids (NEFA). Neither TG nor NEFA are soluble to any extent in water, and their transport to and out of the tissue requires specialized transport mechanisms and adequate blood flow. Subcutaneous adipose tissue blood flow (ATBF) is therefore tightly linked to the tissue's metabolic functioning. ATBF is relatively high (in the fasting state, similar to that of resting skeletal muscle, when expressed per 100 g tissue) and changes markedly in different physiological states. Those most studied are after ingestion of a meal, when there is normally a marked rise in ATBF, and exercise, when ATBF also increases. Pharmacological studies have helped to define the physiological regulation of ATBF. Adrenergic influences predominate in most situations, but nevertheless the regulation of ATBF is complex and depends on the interplay of many different systems. ATBF is downregulated in obesity (when expressed per 100 g tissue), and its responsiveness to meal intake is reduced. However, there is little evidence that this leads to adipose tissue hypoxia in human obesity, and we suggest that, like the downregulation of catecholamine-stimulated lipolysis seen in obesity, the reduction in ATBF represents an adaptation to the increased fat mass. Most information on ATBF has been obtained from studying the subcutaneous abdominal fat depot, but more limited information on lower-body fat depots suggests some similarities, but also some differences: in particular, marked alpha-adrenergic tone, which can reduce the femoral ATBF response to adrenergic stimuli.
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Affiliation(s)
- K N Frayn
- Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, UK
| | - F Karpe
- 1] Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, UK [2] National Institute for Health Research, Oxford Biomedical Research Centre, Oxford University Hospitals Trust, Oxford, UK
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20
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Asmar M, Simonsen L, Arngrim N, Holst JJ, Dela F, Bülow J. Glucose-dependent insulinotropic polypeptide has impaired effect on abdominal, subcutaneous adipose tissue metabolism in obese subjects. Int J Obes (Lond) 2013; 38:259-65. [PMID: 23736366 DOI: 10.1038/ijo.2013.73] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 02/18/2013] [Accepted: 04/04/2013] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Glucose-dependent insulinotropic polypeptide (GIP) appears to have a role in lipid metabolism. Recently, we showed that GIP in combination with hyperinsulinemia and hyperglycemia increases triglyceride uptake in abdominal, subcutaneous adipose tissue in lean humans. It has been suggested that increased GIP secretion in obesity will promote lipid deposition in adipose tissue. In light of the current attempts to employ GIP antagonists in the treatment and prevention of human obesity, the present experiments were performed in order to elucidate whether the adipose tissue lipid metabolism would be enhanced or blunted during a GIP, hyperinsulinemic and hyperglycemic (HI-HG) clamp in obese subjects with either normal glucose tolerance (NGT) or impaired glucose tolerance (IGT). DESIGN Sixteen obese (BMI>30 kg m(-2)) subjects were divided into two groups, based on their plasma glucose response to an oral glucose challenge: (i) NGT and (ii) IGT. Abdominal, subcutaneous adipose tissue lipid metabolism was studied by conducting measurements of arteriovenous concentrations of metabolites and regional adipose tissue blood flow (ATBF) during GIP (1.5 pmol kg(-1) min(-1)) in combination with a HI-HG clamp. RESULTS In both groups, ATBF responses were significantly lower than what we have found previously in healthy, lean subjects (P<0.0001). The flow response was significantly lower in the IGT group than in the NGT group (P=0.03). It was not possible to show any increase in the lipid deposition in adipose tissue under the applied experimental conditions and likewise the circulating triglyceride (TAG) concentrations remained constant. CONCLUSION The applied GIP, HI-HG clamp did not induce any changes in TAG uptake in adipose tissue in obese subjects. This may be due to a blunted increase in ATBF. These experiments therefore suggest that GIP does not have a major role in postprandial lipid metabolism in obese subjects.
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Affiliation(s)
- M Asmar
- 1] Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital, Copenhagen, Denmark [2] Department of Endocrinology and Internal Medicine, Bispebjerg University Hospital, Copenhagen, Denmark [3] Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - L Simonsen
- Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital, Copenhagen, Denmark
| | - N Arngrim
- 1] Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital, Copenhagen, Denmark [2] Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - J J Holst
- 1] Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark [2] The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - F Dela
- Xlab, Center for Healthy Ageing, University of Copenhagen, Copenhagen, Denmark
| | - J Bülow
- 1] Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital, Copenhagen, Denmark [2] Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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21
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Manolopoulos KN, Karpe F, Frayn KN. Marked resistance of femoral adipose tissue blood flow and lipolysis to adrenaline in vivo. Diabetologia 2012; 55:3029-37. [PMID: 22898765 DOI: 10.1007/s00125-012-2676-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 07/05/2012] [Indexed: 01/14/2023]
Abstract
AIMS/HYPOTHESIS Fatty acid entrapment in femoral adipose tissue has been proposed to prevent ectopic fat deposition and visceral fat accumulation, resulting in protection from insulin resistance. Our objective was to test the hypothesis of femoral, compared with abdominal, adipose tissue resistance to adrenergic stimulation in vivo as a possible mechanism. METHODS Regional fatty acid trafficking, along with the measurement of adipose tissue blood flow (ATBF) with (133)Xe washout, was studied with the arteriovenous difference technique and stable isotope tracers in healthy volunteers. Adrenergic agonists (isoprenaline, adrenaline [epinephrine]) were infused either locally by microinfusion or systemically. Local microinfusion of adrenoceptor antagonists (propranolol, phentolamine) was used to characterise specific adrenoceptor subtype effects in vivo. RESULTS Femoral adipose tissue NEFA release and ATBF were lower during adrenaline stimulation than in abdominal tissue (p < 0.001). Mechanistically, femoral adipose tissue displayed a dominant α-adrenergic response during adrenaline stimulation. The α-adrenoceptor blocker, phentolamine, resulted in the 'disinhibition' of the femoral ATBF response to adrenaline (p < 0.001). CONCLUSIONS/INTERPRETATION Fatty acids, once stored in femoral adipose tissue, are not readily released upon adrenergic stimulation. Femoral adipose tissue resistance to adrenaline may contribute to the prevention of ectopic fatty acid deposition.
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Affiliation(s)
- K N Manolopoulos
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK.
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22
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Tobin L, Simonsen L, Galbo H, Bülow J. Vascular and metabolic effects of adrenaline in adipose tissue in type 2 diabetes. Nutr Diabetes 2012; 2:e46. [PMID: 23446661 PMCID: PMC3461355 DOI: 10.1038/nutd.2012.19] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Objective: The aim was to investigate adipose tissue vascular and metabolic effects of an adrenaline infusion in vivo in subjects with and without type 2 diabetes mellitus (T2DM). Design: Clinical intervention study with 1-h intravenous adrenaline infusion. Subjects: Eight male overweight T2DM subjects and eight male weight-matched, non-T2DM subjects were studied before, during and after an 1-h intravenous adrenaline infusion. Adipose tissue blood flow (ATBF) was determined by 133Xenon wash-out technique, and microvascular volume in the adipose tissue was studied by contrast-enhanced ultrasound imaging. Adipose tissue fluxes of glycerol, non-esterified fatty acids (NEFA), triacylglycerol and glucose were measured by Fick's principle after catherisation of a radial artery and a vein draining the abdominal, subcutaneous adipose tissue. Results: ATBF increased similarly in both groups during the adrenaline infusion. One hour post adrenaline, ATBF was still increased in overweight T2DM subjects. Adrenaline increased microvascular volume in non-T2DM subjects while this response was impaired in overweight T2DM subjects. Adrenaline-induced increase in lipolysis was similar in both groups, but NEFA output from adipose tissue was delayed in overweight T2DM subjects. Glucose uptake in adipose tissue increased in non-T2DM subjects during adrenaline infusion but was unchanged in overweight T2DM subjects. This results in a delayed excess release of NEFA from the adipose tissue in overweight T2DM subjects after cessation of the adrenaline infusion. Conclusion: Capillaries in the adipose tissue are recruited by adrenaline in non-T2DM subjects; however, this response is impaired in overweight T2DM subjects. NEFA, released in adipose tissue during adrenaline stimulation, is insufficiently re-esterified in situ in overweight T2DM subjects, probably owing to increased ATBF after adrenaline infusion and inability to increase adipose tissue glucose uptake.
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Affiliation(s)
- L Tobin
- Department of Clinical Physiology and Nuclearmedicine, Bispebjerg Hospital, University of Copenhagen, Copenhagen NV, Denmark
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Bonig H, Papayannopoulou T. Hematopoietic stem cell mobilization: updated conceptual renditions. Leukemia 2012; 27:24-31. [PMID: 22951944 DOI: 10.1038/leu.2012.254] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Despite its specific clinical relevance, the field of hematopoietic stem cell mobilization has received broad attention, owing mainly to the belief that pharmacologic stem cell mobilization might provide clues as to how stem cells are retained in their natural environment, the bone marrow 'niche'. Inherent to this knowledge is also the desire to optimally engineer stem cells to interact with their target niche (such as after transplantation), or to lure malignant stem cells out of their protective niches (in order to kill them), and in general to decipher the niche's structural components and its organization. Whereas, with the exception of the recent addition of CXCR4 antagonists to the armamentarium for mobilization of patients refractory to granulocyte colony-stimulating factor alone, clinical stem cell mobilization has not changed significantly over the last decade or so, much effort has been made trying to explain the complex mechanism(s) by which hematopoietic stem and progenitor cells leave the marrow. This brief review will report some of the more recent advances about mobilization, with an attempt to reconcile some of the seemingly inconsistent data in mobilization and to interject some commonalities among different mobilization regimes.
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Affiliation(s)
- H Bonig
- Department of Medicine/Division of Hematology, University of Washington, Seattle, WA 98198-7720, USA
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Donato AJ, Henson GD, Morgan RG, Enz RA, Walker AE, Lesniewski LA. TNF-α impairs endothelial function in adipose tissue resistance arteries of mice with diet-induced obesity. Am J Physiol Heart Circ Physiol 2012; 303:H672-9. [PMID: 22821989 DOI: 10.1152/ajpheart.00271.2012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We tested the hypothesis that high fat (HF) feeding results in endothelial dysfunction in resistance arteries of epididymal white adipose tissue (eWAT) and is mediated by adipose tissue inflammation. When compared with normal chow (NC)-fed mice (n = 17), HF-fed male B6D2F1 mice were glucose intolerant and insulin resistant as assessed by glucose tolerance test (area under the curve; HF, 18,174 ± 1,889 vs. NC, 15,814 ± 666 mg·dl(-1)·min(-1); P < 0.05) and the homeostatic model assessment (HF, 64.1 ± 4.3 vs. NC, 85.7 ± 6.4; P = 0.05). HF diet-induced metabolic dysfunction was concomitant with a proinflammatory eWAT phenotype characterized by greater macrophage infiltration (HF, 3.9 ± 0.8 vs. NC, 0.8 ± 0.4%; P = 0.01) and TNF-α (HF, 22.6 ± 4.3 vs. NC, 11.4 ± 2.5 pg/dl; P < 0.05) and was associated with resistance artery dysfunction, evidenced by impaired endothelium-dependent dilation (EDD) (maximal dilation; HF, 49.2 ± 10.7 vs. NC, 92.4 ± 1.4%; P < 0.01). Inhibition of nitric oxide (NO) synthase by N(ω)-nitro-L-arginine methyl ester (L-NAME) reduced dilation in NC (28.9 ± 6.3%; P < 0.01)- and tended to reduce dilation in HF (29.8 ± 9.9%; P = 0.07)-fed mice, eliminating the differences in eWAT artery EDD between NC- and HF-fed mice, indicative of reduced NO bioavailability in eWAT resistance arteries after HF feeding. In vitro treatment of excised eWAT arteries with recombinant TNF-α (rTNF) impaired EDD (P < 0.01) in NC (59.7 ± 10.9%)- but not HF (59.0 ± 9.3%)-fed mice. L-NAME reduced EDD in rTNF-treated arteries from both NC (21.9 ± 6.4%)- and HF (29.1 ± 9.2%)-fed mice (both P < 0.01). In vitro treatment of arteries with a neutralizing antibody against TNF-α (abTNF) improved EDD in HF (88.2 ± 4.6%; P = 0.05)-fed mice but was without effect on maximal dilation in NC (89.0 ± 5.1%)-fed mice. L-NAME reduced EDD in abTNF-treated arteries from both NC (25.4 ± 7.5%)- and HF (27.1 ± 16.8%)-fed mice (both P < 0.01). These results demonstrate that inflammation in the visceral adipose tissue resulting from diet-induced obesity impairs endothelial function and NO bioavailability in the associated resistance arteries. This dysfunction may have important implications for adipose tissue blood flow and appropriate tissue function.
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Affiliation(s)
- Anthony J Donato
- Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, 84148, USA
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Alemany M. Regulation of adipose tissue energy availability through blood flow control in the metabolic syndrome. Free Radic Biol Med 2012; 52:2108-19. [PMID: 22542444 DOI: 10.1016/j.freeradbiomed.2012.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 03/12/2012] [Accepted: 03/13/2012] [Indexed: 12/25/2022]
Abstract
Maintenance of blood flow rate is a critical factor for tissue oxygen and substrate supply. The potentially large mass of adipose tissue deeply influences the body distribution of blood flow. This is due to increased peripheral resistance in obesity and the role of this tissue as the ultimate destination of unused excess of dietary energy. However, adipose tissue cannot grow indefinitely, and the tissue must defend itself against the avalanche of nutrients provoking inordinate growth and inflammation. In the obese, large adipose tissue masses show lower blood flow, limiting the access of excess circulating substrates. Blood flow restriction is achieved by vasoconstriction, despite increased production of nitric oxide, the vasodilatation effects of which are overridden by catecholamines (and probably also by angiotensin II and endothelin). Decreased blood flow reduces the availability of oxygen, provoking massive glycolysis (hyperglycemic conditions), which results in the production of lactate, exported to the liver for processing. However, this produces local acidosis, which elicits the rapid dissociation of oxyhemoglobin, freeing bursts of oxygen in localized zones of the tissue. The excess of oxygen (and of nitric oxide) induces the production of reactive oxygen species, which deeply affect the endothelial, blood, and adipose cells, inducing oxidative and nitrosative damage and eliciting an increased immune response, which translates into inflammation. The result of the defense mechanism for adipose tissue, localized vasoconstriction, may thus help develop a more generalized pathologic response within the metabolic syndrome parameters, extending its effects to the whole body.
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Affiliation(s)
- Marià Alemany
- Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain.
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Sotornik R, Brassard P, Martin E, Yale P, Carpentier AC, Ardilouze JL. Update on adipose tissue blood flow regulation. Am J Physiol Endocrinol Metab 2012; 302:E1157-70. [PMID: 22318953 DOI: 10.1152/ajpendo.00351.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
According to Fick's principle, any metabolic or hormonal exchange through a given tissue depends on the product of the blood flow to that tissue and the arteriovenous difference. The proper function of adipose tissue relies on adequate adipose tissue blood flow (ATBF), which determines the influx and efflux of metabolites as well as regulatory endocrine signals. Adequate functioning of adipose tissue in intermediary metabolism requires finely tuned perfusion. Because metabolic and vascular processes are so tightly interconnected, any disruption in one will necessarily impact the other. Although altered ATBF is one consequence of expanding fat tissue, it may also aggravate the negative impacts of obesity on the body's metabolic milieu. This review attempts to summarize the current state of knowledge on adipose tissue vascular bed behavior under physiological conditions and the various factors that contribute to its regulation as well as the possible participation of altered ATBF in the pathophysiology of metabolic syndrome.
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Affiliation(s)
- Richard Sotornik
- Diabetes and Metabolism Research Group, Division of Endocrinology, Department of Medicine, Centre Hospitalier, Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Thompson D, Karpe F, Lafontan M, Frayn K. Physical activity and exercise in the regulation of human adipose tissue physiology. Physiol Rev 2012; 92:157-91. [PMID: 22298655 DOI: 10.1152/physrev.00012.2011] [Citation(s) in RCA: 210] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Physical activity and exercise are key components of energy expenditure and therefore of energy balance. Changes in energy balance alter fat mass. It is therefore reasonable to ask: What are the links between physical activity and adipose tissue function? There are many complexities. Physical activity is a multifaceted behavior of which exercise is just one component. Physical activity influences adipose tissue both acutely and in the longer term. A single bout of exercise stimulates adipose tissue blood flow and fat mobilization, resulting in delivery of fatty acids to skeletal muscles at a rate well-matched to metabolic requirements, except perhaps in vigorous intensity exercise. The stimuli include adrenergic and other circulating factors. There is a period following an exercise bout when fatty acids are directed away from adipose tissue to other tissues such as skeletal muscle, reducing dietary fat storage in adipose. With chronic exercise (training), there are changes in adipose tissue physiology, particularly an enhanced fat mobilization during acute exercise. It is difficult, however, to distinguish chronic "structural" changes from those associated with the last exercise bout. In addition, it is difficult to distinguish between the effects of training per se and negative energy balance. Epidemiological observations support the idea that physically active people have relatively low fat mass, and intervention studies tend to show that exercise training reduces fat mass. A much-discussed effect of exercise versus calorie restriction in preferentially reducing visceral fat is not borne out by meta-analyses. We conclude that, in addition to the regulation of fat mass, physical activity may contribute to metabolic health through beneficial dynamic changes within adipose tissue in response to each activity bout.
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Nellemann B, Gormsen LC, Sørensen LP, Christiansen JS, Nielsen S. Impaired insulin-mediated antilipolysis and lactate release in adipose tissue of upper-body obese women. Obesity (Silver Spring) 2012; 20:57-64. [PMID: 21959346 DOI: 10.1038/oby.2011.290] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Upper-body/visceral obesity is associated with abnormalities of free fatty acid (FFA) metabolism and greater risk of developing type 2 diabetes compared with lower-body obesity. In lean subjects lipolysis is readily suppressed by insulin; however, metabolic inflexibility with respect to antilipolysis is a frequent finding in obesity, partly determined by body composition. This study investigates effects of insulin on regional adipose tissue lipolysis and lactate levels in upper-body overweight/obese (UBO), lower-body overweight/obese (LBO), and lean women. The microdialysis technique was used to assess adipose tissue glycerol and lactate concentrations in abdominal and femoral fat during a 5-h basal period and a 2-h hyperinsulinemic euglycemic clamp. The main findings were that the antilipolytic effect of insulin was attenuated in abdominal fat of UBO (glycerol reduction, abd (%): UBO 40.4 (-14 to 66), LBO 46.0 (-8 to 66), lean 66.2 (2-78), ANOVA, P < 0.05), and in femoral fat in both obese groups (glycerol reduction, fem (%): UBO 44.4 (35-67), LBO 44.4 (0-63), lean 65.0 (43-79), ANOVA, P < 0.05). Further, abdominal fat insulin-mediated increase in lactate concentration was greater in lean women compared with UBO women (lactate increase, abd (%): UBO -6.1 (-37.1 to 57.4), LBO 16.5 (-32.2 to 112.5), lean 51.4 (-45.7 to 162.9), P < 0.05), whereas no differences were found between groups in femoral fat (lactate increase, fem (%), UBO -12.9 (-43 to 24), LBO 12.7 (-30.7 to 92), lean 27.6 (-9.5 to 123.8), not significant). Respiratory exchange ratio (RER) increased significantly and similarly in all groups. So, UBO women were metabolically inflexible with respect to insulins antilipolytic and lactate increasing effects in abdominal adipose tissue. These phenomena are probably both consequences of insulin resistance of adipose tissue.
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Affiliation(s)
- Birgitte Nellemann
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
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van de Woestijne AP, Monajemi H, Kalkhoven E, Visseren FLJ. Adipose tissue dysfunction and hypertriglyceridemia: mechanisms and management. Obes Rev 2011; 12:829-40. [PMID: 21749607 DOI: 10.1111/j.1467-789x.2011.00900.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Elevated plasma triglyceride levels, as often seen in obese subjects, are independently associated with an increased risk of cardiovascular diseases. By secreting adipokines (such as adiponectin and leptin) and other proteins (such as lipoprotein lipase and cholesteryl ester transferase protein), adipose tissue affects triglyceride metabolism. In obesity, adipocyte hypertrophy leads to many changes in adipocyte function and production of anti- and pro-inflammatory cytokines. Furthermore, free fatty acids are released into the circulation contributing to insulin resistance. Adipose tissue dysfunction will eventually lead to abnormalities in lipid metabolism, such as hypertriglyceridemia (due to increased hepatic very-low-density lipoprotein production and decreased triglyceride hydrolysis), small dense low-density lipoprotein particles, remnant lipoproteins and low high-density lipoprotein cholesterol levels, all associated with a higher risk for the development of cardiovascular diseases. The clinical implications of elevated plasma triglycerides are still a matter of debate. Understanding the pathophysiology of adipose tissue dysfunction in obesity, which is becoming a pandemic condition, is essential for designing appropriate therapeutic interventions. Lifestyle changes are important to improve adipose tissue function in obese patients. Pharmacological interventions to improve adipose tissue function need further evaluation. Although statins are not very potent in reducing plasma triglycerides, they remain the mainstay of therapy for cardiovascular risk reduction in high-risk patients.
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Affiliation(s)
- A P van de Woestijne
- Department of Vascular Medicine, University Medical Center, Utrecht, the Netherlands Department of Metabolic and Endocrine Diseases, University Medical Center, Utrecht, the Netherlands
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Ardilouze JL, Sotorník R, Dennis LA, Fielding BA, Frayn KN, Karpe F. Failure to increase postprandial blood flow in subcutaneous adipose tissue is associated with tissue resistance to adrenergic stimulation. DIABETES & METABOLISM 2011; 38:27-33. [PMID: 21865069 DOI: 10.1016/j.diabet.2011.06.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2010] [Revised: 05/30/2011] [Accepted: 06/21/2011] [Indexed: 12/29/2022]
Abstract
AIMS Adequate adipose tissue blood flow (ATBF) is essential for its metabolic and endocrine functions. From a metabolic point of view, sufficient increases in ATBF after meals permits full storage of excess energy into fat, thus protecting other tissues against the toxic effects of fatty acids and glucose spillover. It was previously shown that postprandial increases in ATBF are blunted in obese and insulin-resistant subjects, and that much of the postprandial ATBF response is the result of β-adrenergic activation. Examination of previously recorded data on postprandial ATBF responses revealed an underlying heterogeneity, with postprandial ATBF being largely unresponsive to food stimuli in a substantial proportion of normal weight healthy people (low responders). Our study tests the hypothesis that this unresponsive pattern is due to resistance to β-adrenergic stimulation in adipose tissue. METHODS Five responders and five low responders were selected from a previously studied cohort and matched for BMI (20.5±0.7 vs 22±1 kg/m(2), respectively), gender (male/female: 2/3) and age (30±3 vs 37±6 years). Subcutaneous adipose tissue microinfusions of stepwise increasing doses of isoproterenol were performed with concomitant monitoring of blood flow, using the (133)Xenon washout technique. RESULTS Although BMI was similar between responders and low responders, there were significant differences in fat mass (9.9±1.6 vs 14.4±1.6 kg; P<0.05) and four-point skinfold thickness (33±4 vs 52±16 mm; P<0.05). Lack of ATBF response to oral glucose was confirmed in the low responder group. In responders, ATBF was higher at baseline (5.4±1 vs 3.4±1 mL/min/100 g of tissue) and responded more distinctly to increasing isoproterenol doses (10(-8) M: 7.6±1.4 vs 4.9±1; 10(-6) M: 12.5±1.7 vs 7.5±1.6; and 10(-4) M: 20 ±1.7 vs 9±0.9 mL/min/100 g of tissue). CONCLUSION These data suggest that the lack of glucose-stimulated ATBF is associated with resistance to sympathetic activation in adipose tissue.
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Affiliation(s)
- J-L Ardilouze
- Division of Endocrinology, Department of Medicine, Université de Sherbrooke, 3001, 12th Avenue North, J1H 5N4 Sherbrooke, Quebec, Canada.
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Andersson J, Karpe F, Sjöström LG, Riklund K, Söderberg S, Olsson T. Association of adipose tissue blood flow with fat depot sizes and adipokines in women. Int J Obes (Lond) 2011; 36:783-9. [PMID: 21792171 DOI: 10.1038/ijo.2011.152] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To explore possible associations between adipose tissue (AT) blood flow (ATBF), AT depot sizes and adipocyte-derived hormones (adipokines) in women. SUBJECTS In all, 43 healthy women were divided into four groups: normal-weight (n=11) and obese (n=11) pre-menopausal women and normal-weight (n=10) and obese (n=11) post-menopausal women. METHODS Fasting levels of adipokines were obtained, and a single-slice computed tomography scan at the level of L4-L5 was used to estimate fat depot sizes. ATBF was assessed by xenon washout while in a fasting state and after oral glucose load. We also measured glucose, insulin and non-esterified fatty acids. RESULTS Total, subcutaneous and visceral AT areas strongly correlated with ATBF (all P<0.001). Circulating leptin levels strongly and inversely correlated with ATBF (P=0.001), but this association did not remain after adjustment for body mass index. Adiponectin was not associated with blood flow. CONCLUSION ATBF is closely linked to subcutaneous and visceral AT size. Further analyses are needed to determine possible mediators of this association, including mechanistic studies to assess a putative role for leptin as a significant modulator of blood flow.
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Affiliation(s)
- J Andersson
- Department of Public Health and Clinical Medicine, Medicine, Umeå University, Umeå, Sweden.
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Abstract
To fulfill its role as the major energy-storing tissue, adipose has several unique properties that cannot be seen in any other organ, including an almost unlimited capacity to expand in a non-transformed state. As such, the tissue requires potent mechanisms to remodel, acutely and chronically. Adipocytes can rapidly reach the diffusional limit of oxygen during growth; hypoxia is therefore an early determinant that limits healthy expansion. Proper expansion requires a highly coordinated response among many different cell types, including endothelial precursor cells, immune cells, and preadipocytes. There are therefore remarkable similarities between adipose expansion and growth of solid tumors, a phenomenon that presents both an opportunity and a challenge, since pharmacological interventions supporting healthy adipose tissue adaptation can also facilitate tumor growth.
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Affiliation(s)
- Kai Sun
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8549, USA
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Martin E, Brassard P, Gagnon-Auger M, Yale P, Carpentier AC, Ardilouze JL. Subcutaneous adipose tissue metabolism and pharmacology: a new investigative technique. Can J Physiol Pharmacol 2011; 89:383-91. [DOI: 10.1139/y11-039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
According to the Fick principle, any metabolic or hormonal exchange through a given tissue depends on the product of blood flow by arteriovenous difference. Because adipose tissue plays dual storage and endocrine roles, regulation of adipose tissue blood flow (ATBF) is of pivotal importance. Monitoring ATBF in humans can be achieved through different methodologies, such as the 133Xe washout technique, considered to be the “gold standard”, as well as microdialysis and other methods that are not well validated as of yet. This report describes a new method, called “adipose tissue microinfusion” or “ATM”, which simultaneously quantifies ATBF by combining the 133Xe washout technique together with variations of ATBF induced by local infusion of vasoactive agents. The most appropriate site for ATM investigation is the subcutaneous adipose tissue of the anterior abdominal wall. This innovative method conveniently enables the direct comparison of the effects on ATBF of any vasoactive compound, drug, or hormone against a contralateral saline control. The ATM method improves the accuracy and feasibility of physiological and pharmacological studies on the regulation of ATBF in vivo in humans.
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Affiliation(s)
- Elizabeth Martin
- Diabetes and Metabolism Research Group, Division of Endocrinology, Department of Medicine, Sherbrooke University Hospital Centre, Sherbrooke, QC J1H 5N4, Canada
| | - Pascal Brassard
- Diabetes and Metabolism Research Group, Division of Endocrinology, Department of Medicine, Sherbrooke University Hospital Centre, Sherbrooke, QC J1H 5N4, Canada
| | - Maude Gagnon-Auger
- Diabetes and Metabolism Research Group, Division of Endocrinology, Department of Medicine, Sherbrooke University Hospital Centre, Sherbrooke, QC J1H 5N4, Canada
| | - Philippe Yale
- Diabetes and Metabolism Research Group, Division of Endocrinology, Department of Medicine, Sherbrooke University Hospital Centre, Sherbrooke, QC J1H 5N4, Canada
| | - André C. Carpentier
- Diabetes and Metabolism Research Group, Division of Endocrinology, Department of Medicine, Sherbrooke University Hospital Centre, Sherbrooke, QC J1H 5N4, Canada
| | - Jean-Luc Ardilouze
- Diabetes and Metabolism Research Group, Division of Endocrinology, Department of Medicine, Sherbrooke University Hospital Centre, Sherbrooke, QC J1H 5N4, Canada
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Kim J, Saidel GM, Kalhan SC. Regulation of Adipose Tissue Metabolism in Humans: Analysis of Responses to the Hyperinsulinemic-Euglycemic Clamp Experiment. Cell Mol Bioeng 2011; 4:281-301. [PMID: 23646067 DOI: 10.1007/s12195-011-0162-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The suppression of lipolysis is one of the key metabolic responses of the adipose tissue during hyperinsulinemia. The failure to respond and resulting increase in plasma fatty acids could contribute to the development of insulin resistance and perturbations in the fuel homeostasis in the whole body. In this study, a mechanistic, computational model of adipose tissue metabolism in vivo has been enhanced to simulate the physiological responses during hyperinsulinemic-euglycemic clamp experiment in humans. The model incorporates metabolic intermediates and pathways that are important in the fed state. In addition, it takes into account the heterogeneity of triose phosphate pools (glycolytic vs. glyceroneogenic), within the adipose tissue. The model can simulate not only steady-state responses at different insulin levels, but also concentration dynamics of major metabolites in the adipose tissue venous blood in accord with the in vivo data. Simulations indicate that (1) regulation of lipoprotein lipase (LPL) reaction is important when the intracellular lipolysis is suppressed by insulin; (2) intracellular diglyceride levels can affect the regulatory mechanisms; and (3) glyceroneogenesis is the dominant pathway for glycerol-3-phosphate synthesis even in the presence of increased glucose uptake by the adipose tissue. Reduced redox and increased phosphorylation states provide a favorable milieu for glyceroneogenesis in response to insulin. A parameter sensitivity analysis predicts that insulin-stimulated glucose uptake would be more severely affected by impairment of GLUT4 translocation and glycolysis than by impairment of glycogen synthesis and pyruvate oxidation. Finally, simulations predict metabolic responses to altered expression of phosphoenolpyruvate carboxykinase (PEP-CK). Specifically, the increase in the rate of re-esterification of fatty acids observed experimentally with the overexpression of PEPCK in the adipose tissue would be accompanied by the up-regulation of acyl Co-A synthase.
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Affiliation(s)
- Jaeyeon Kim
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA ; Center for Modeling Integrated Metabolic Systems, Case Western Reserve University, Cleveland, OH 44106, USA ; Department of Pathobiology, Lerner Research Institute, NE4-203, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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Asmar M, Simonsen L, Madsbad S, Stallknecht B, Holst JJ, Bülow J. Glucose-dependent insulinotropic polypeptide may enhance fatty acid re-esterification in subcutaneous abdominal adipose tissue in lean humans. Diabetes 2010; 59:2160-3. [PMID: 20547981 PMCID: PMC2927937 DOI: 10.2337/db10-0098] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Glucose-dependent insulinotropic polypeptide (GIP) has been implicated in lipid metabolism in animals. In humans, however, there is no clear evidence of GIP effecting lipid metabolism. The present experiments were performed in order to elucidate the effects of GIP on regional adipose tissue metabolism. RESEARCH DESIGN AND METHODS Eight healthy subjects were studied on four different occasions. Abdominal subcutaneous adipose tissue metabolism was assessed by measuring arterio-venous concentration differences and regional adipose tissue blood flow during GIP (1.5 pmol/kg/min) or saline infused intravenously alone or in combination with a hyperinsulinemic-hyperglycemic (HI-HG) clamp. RESULTS During GIP and HI-HG clamp, abdominal subcutaneous adipose tissue blood flow, hydrolysis of circulating triacylglycerol (TAG) (P = 0.009), and glucose uptake (P = 0.03) increased significantly while free fatty acid (FFA) output (P = 0.04) and FFA/glycerol release ratio (P = 0.02) decreased compared with saline and HI-HG clamp. CONCLUSIONS In conclusion, GIP in combination with hyperinsulinemia and slight hyperglycemia increased adipose tissue blood flow, glucose uptake, and FFA re-esterification, thus resulting in increased TAG deposition in abdominal subcutaneous adipose tissue.
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Affiliation(s)
- Meena Asmar
- Department of Clinical Physiology/Nuclear Medicine, Bispebjerg Hospital, Copenhagen, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lene Simonsen
- Department of Clinical Physiology/Nuclear Medicine, Bispebjerg Hospital, Copenhagen, Denmark
| | - Sten Madsbad
- Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark
| | - Bente Stallknecht
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Juul Holst
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Bülow
- Department of Clinical Physiology/Nuclear Medicine, Bispebjerg Hospital, Copenhagen, Denmark
- Corresponding author: Jens Bülow,
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Tobin L, Simonsen L, Bülow J. Real-time contrast-enhanced ultrasound determination of microvascular blood volume in abdominal subcutaneous adipose tissue in man. Evidence for adipose tissue capillary recruitment. Clin Physiol Funct Imaging 2010; 30:447-52. [DOI: 10.1111/j.1475-097x.2010.00964.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Regulation of subcutaneous adipose tissue blood flow is related to measures of vascular and autonomic function. Clin Sci (Lond) 2010; 119:313-22. [PMID: 20518748 DOI: 10.1042/cs20100066] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Appropriate blood vessel function is important to cardiovascular health. Adipose tissue plays an important role in metabolic homoeostasis, and subcutaneous abdominal ATBF (adipose tissue blood flow) is responsive to nutritional stimuli. This response is impaired in obesity, suggesting parallels with endothelial function. In the present study, we assessed whether regulation of ATBF is related to the regulation of endothelial function, assessed by FMD (flow-mediated vasodilatation) of the brachial artery. Impaired FMD is a marker of atherosclerotic risk, so we also assessed relationships between ATBF and a marker of atherosclerosis, common carotid artery IMT (intima-media thickness). As ATBF is responsive to sympatho-adrenal stimuli, we also investigated relationships with HRV (heart rate variability). A total of 79 healthy volunteers (44 female) were studied after fasting and after ingestion of 75 g of glucose. FMD, fasting ATBF and the responsiveness of ATBF to glucose were all negatively related to BMI (body mass index), confirming the adverse cardiovascular effects of adiposity. FMD was related to fasting ATBF (rs=0.32, P=0.008) and, at least in males, this relationship was independent of BMI (P=0.02). Common carotid artery IMT, measured in a subset of participants, was negatively related to fasting ATBF [rs=-0.51, P=0.02 (n=20)]. On the other hand, ATBF responsiveness to glucose had no relationship with either FMD or IMT. In multiple regression models, both fasting and stimulated ATBF had relationships with HRV. In conclusion, our results show that the regulation of ATBF has features in common with endothelial function, but also relationships with autonomic cardiovascular control as reflected in HRV.
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Andersson J, Sjöström LG, Karlsson M, Wiklund U, Hultin M, Karpe F, Olsson T. Dysregulation of subcutaneous adipose tissue blood flow in overweight postmenopausal women. Menopause 2010; 17:365-71. [DOI: 10.1097/gme.0b013e3181c12b26] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Hodson L, Fielding BA. Trafficking and partitioning of fatty acids: the transition from fasted to fed state. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/clp.09.72] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Abstract
Body fat distribution is an important metabolic and cardiovascular risk factor, because the proportion of abdominal to gluteofemoral body fat correlates with obesity-associated diseases and mortality. Here, we review the evidence and possible mechanisms that support a specific protective role of gluteofemoral body fat. Population studies show that an increased gluteofemoral fat mass is independently associated with a protective lipid and glucose profile, as well as a decrease in cardiovascular and metabolic risk. Studies of adipose tissue physiology in vitro and in vivo confirm distinct properties of the gluteofemoral fat depot with regards to lipolysis and fatty acid uptake: in day-to-day metabolism it appears to be more passive than the abdominal depot and it exerts its protective properties by long-term fatty acid storage. Further, a beneficial adipokine profile is associated with gluteofemoral fat. Leptin and adiponectin levels are positively associated with gluteofemoral fat while the level of inflammatory cytokines is negatively associated. Finally, loss of gluteofemoral fat, as observed in Cushing's syndrome and lipodystrophy is associated with an increased metabolic and cardiovascular risk. This underlines gluteofemoral fat's role as a determinant of health by the long-term entrapment of excess fatty acids, thus protecting from the adverse effects associated with ectopic fat deposition.
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Clausen TS, Kaastrup P, Stallknecht B. Proinflammatory tissue response and recovery of adipokines during 4 days of subcutaneous large-pore microdialysis. J Pharmacol Toxicol Methods 2009; 60:281-7. [DOI: 10.1016/j.vascn.2009.03.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 03/17/2009] [Indexed: 12/27/2022]
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Clausen TS, Kaastrup P, Stallknecht B. Effect of insulin catheter wear-time on subcutaneous adipose tissue blood flow and insulin absorption in humans. Diabetes Technol Ther 2009; 11:575-80. [PMID: 19764836 DOI: 10.1089/dia.2009.0058] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Insertion of an insulin catheter for continuous subcutaneous insulin infusion into the subcutaneous adipose tissue (SAT) causes a tissue trauma that may have consequences for insulin absorption. We evaluated the importance of insulin catheter wear-time on subcutaneous adipose tissue blood flow (ATBF) and absorption of the rapid-acting insulin analog insulin aspart over a period of 4 days. METHODS Teflon insulin catheters (Medtronic, Minneapolis, MN) were inserted into the abdominal SAT of 10 healthy men without diabetes (mean +/- SEM age, 23.0 +/- 1.1 years; body mass index, 22.1 +/- 0.7 kg/m(2)) and connected to an insulin pump delivering a constant rate of isotonic saline for 4 days. Subjects participated in four study days (days 0, 1, 2, and 4) during which ATBF around the catheter tip was measured by (133)Xe clearance and absorption of an insulin aspart bolus (0.1 U/kg) was measured for 4 h. RESULTS ATBF increased from day 0 to day 2 after catheter insertion (2.6 +/- 0.6 to 4.5 +/- 0.8 mL/100 g/min; P = 0.030). By day 4, ATBF had returned to day 0 level. Time to peak plasma insulin aspart concentration after bolus administration decreased with catheter wear-time from 55 +/- 3 min on day 0 to 45 +/- 4 min on day 4 (P = 0.019). Neither peak plasma concentration nor area under the curve of insulin aspart changed significantly. CONCLUSIONS Insertion of a Teflon insulin catheter into the SAT results in increased ATBF and faster absorption of insulin aspart in a period of 4 days without any change in the total amount of insulin aspart absorbed.
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A Model of NEFA Dynamics with Focus on the Postprandial State. Ann Biomed Eng 2009; 37:1897-909. [DOI: 10.1007/s10439-009-9738-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Accepted: 06/04/2009] [Indexed: 11/29/2022]
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Perez-Matute P, Neville MJ, Tan GD, Frayn KN, Karpe F. Transcriptional control of human adipose tissue blood flow. Obesity (Silver Spring) 2009; 17:681-8. [PMID: 19165164 DOI: 10.1038/oby.2008.606] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Adipose tissue is highly vascularized and expresses several genes involved in vasodilatory and vasoconstrictive regulation. We took a transcriptional approach to study the relationships between adipose tissue blood flow (ATBF) and genes involved in vasoactive processes. As ATBF is impaired in obesity, we tested whether body weight interfered with the transcriptional regulation of ATBF. The mRNA content (real-time PCR) of 26 genes was quantified in subcutaneous adipose tissue biopsies from 28 healthy men with a wide range of BMI. ATBF was measured by 133Xe washout. None of the transcripts was related to fasting ATBF (ATBFF). However, the expression levels of two transcripts involved in vasodilation (natriuretic peptide receptor A/guanylate cyclase A (NPRA) and endothelial nitric oxide synthase (eNOS)) were positively associated with postprandial ATBF (r = 0.53 and r = 0.55, P < 0.01, respectively). Although BMI was negatively related to the mRNA content of NPRA and eNOS (r = -0.78 and r = -0.63, P < 0.01, respectively), the strong associations found between postprandial ATBF and the two transcripts were not affected by obesity. Several genes were subject to coordinated regulation of expression. This study demonstrates for the first time that ATBF responsiveness to nutrient intake is related to the transcription of two genes expressed in adipose tissue and directly involved in vasodilatory actions (eNOS and NPRA), suggesting that part of the regulation of ATBF is at a transcriptional level. Interestingly, these associations were not secondary to changes in BMI. We also found that certain genes involved in the regulation of ATBF are subject to coordinate regulation of expression suggesting physiological autoregulation.
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Affiliation(s)
- Patricia Perez-Matute
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Oxford, UK
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van Baak MA. Meal-induced activation of the sympathetic nervous system and its cardiovascular and thermogenic effects in man. Physiol Behav 2008; 94:178-86. [DOI: 10.1016/j.physbeh.2007.12.020] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Revised: 12/20/2007] [Accepted: 12/21/2007] [Indexed: 12/01/2022]
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Goossens GH, Karpe F. Human adipose tissue blood flow and micromanipulation of human subcutaneous blood flow. Methods Mol Biol 2008; 456:97-107. [PMID: 18516555 DOI: 10.1007/978-1-59745-245-8_7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Regulation of blood flow in tissues such as skeletal muscle, liver, and adipose tissue is needed to meet the changing local metabolic and physiological demands under varying conditions. In healthy individuals, adipose tissue blood flow (ATBF) is remarkably responsive to meal ingestion, but changes in ATBF in response to other physiological stimuli, such as stress and physical exercise, have also been noted. The ATBF response to nutrient intake may be of particular importance in the regulation of metabolism by facilitating transport of nutrients as well as signaling between adipose tissue and other metabolically active tissues. A reduction in both fasting and postprandial ATBF has been observed in obesity; this impairment is associated with insulin resistance. A better understanding of the physiological basis for (nutritional) regulation of ATBF may therefore give insight to the relationship between disturbances in ATBF and the metabolic disturbances observed in response to insulin resistance. In this chapter, we describe some different approaches to quantify human ATBF, with a particular emphasis on the 133xenon wash-out technique and a method by which regulatory properties of subcutaneous ATBF can be studied by pharmacological micromanipulation (microinfusion).
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Affiliation(s)
- Gijs H Goossens
- Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
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Dimitriadis G, Lambadiari V, Mitrou P, Maratou E, Boutati E, Panagiotakos DB, Economopoulos T, Raptis SA. Impaired postprandial blood flow in adipose tissue may be an early marker of insulin resistance in type 2 diabetes. Diabetes Care 2007; 30:3128-30. [PMID: 17890315 DOI: 10.2337/dc07-0699] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE We investigated the changes in subcutaneous adipose tissue blood flow (ATBF) after a meal in the various stages of type 2 diabetes. RESEARCH DESIGN AND METHODS Five groups were examined: healthy control subjects, first-degree relatives of subjects with type 2 diabetes, subjects with impaired glucose tolerance (IGT), subjects with type 2 diabetes and postprandial hyperglycemia but normal fasting plasma glucose levels (diabetes group A [DMA]), and subjects with type 2 diabetes with both postprandial and fasting hyperglycemia (diabetes group B [DMB]). ATBF was measured with (133)Xe. RESULTS ATBF was higher in control subjects (1,507 +/- 103 ml/100 cm(3) tissue x min) versus relatives and IGT, DMA, and DMB subjects (845 +/- 123, 679 +/- 69, 765 +/- 60, and 757 +/- 69 ml/100 cm(3) tissue x min, respectively; P < 0.001). Insulin sensitivity index (ISI) in control subjects (82 +/- 3 mg x l(2)/mmol x mU x min) was higher versus that for relatives and IGT, DMA, and DMB subjects (60 +/- 3, 45 +/- 1, 40 +/- 6, and 29 +/- 4 mg x l(2)/mmol x mU x min, respectively; P < 0.0001). ISI was positively associated with peak-baseline ATBF (beta coefficient 0.029 +/- 0.013, P = 0.03). CONCLUSIONS After meal ingestion, insulin-stimulated ATBF was decreased in relatives and and IGT, DMA, and DMB subjects. This defect could be an early marker of insulin resistance that precedes the development of type 2 diabetes.
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Affiliation(s)
- George Dimitriadis
- 2nd Department of Internal Medicine--Propaedeutic and Research Institute, Athens University Medical School, Attikon University Hospital Athens, Greece.
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Enevoldsen LH, Polak J, Simonsen L, Hammer T, Macdonald I, Crampes F, de Glisezinski I, Stich V, Bülow J. Post-exercise abdominal, subcutaneous adipose tissue lipolysis in fasting subjects is inhibited by infusion of the somatostatin analogue octreotide. Clin Physiol Funct Imaging 2007; 27:320-6. [PMID: 17697029 DOI: 10.1111/j.1475-097x.2007.00754.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
To determine whether blockade of the exercise-induced increase in growth hormone (GH) secretion may affect the regional lipolytic rate in the post-exercise recovery period, the aim of the present experiments was to study the effect of infusion of the somatostatin analogue octreotide on the s.c., abdominal adipose tissue metabolism, before, during and after exercise in healthy, fasting, young male subjects. The adipose tissue net releases of fatty acids and glycerol were measured by arterio-venous catheterizations and simultaneous measurements of adipose tissue blood flow with the local Xe-clearance method. Nine subjects were studied during 1-h basal rest, and then during continuous octreotide infusion during 1-h rest, 1-h exercise at 50% of maximal oxygen consumption and 4-h post-exercise rest. A control study on seven subjects was performed under similar conditions but without octreotide infusion. The results show that octreotide infusion during rest increased lipolysis and fatty acid release from the abdominal, s.c. adipose tissue. The exercise-induced increase in lipolysis and fatty acid release does not seem to be affected by octreotide when compared with the control study without octreotide infusion while the post-exercise increase in lipolysis is inhibited by octreotide, suggesting that the exercise-induced increase in GH secretion plays a role for the post-exercise lipolysis in s.c., abdominal adipose tissue.
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Affiliation(s)
- Lotte H Enevoldsen
- Department of Clinical Physiology, Bispebjerg Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark
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Laclaustra M, Corella D, Ordovas JM. Metabolic syndrome pathophysiology: the role of adipose tissue. Nutr Metab Cardiovasc Dis 2007; 17:125-139. [PMID: 17270403 DOI: 10.1016/j.numecd.2006.10.005] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Accepted: 10/24/2006] [Indexed: 12/25/2022]
Abstract
Several pathophysiological explanations for the metabolic syndrome have been proposed involving insulin resistance, chronic inflammation and ectopic fat accumulation following adipose tissue saturation. However, current concepts create several paradoxes, including limited cardiovascular risk reduction with intensive glucose control in diabetics, therapies that result in weight gain (PPAR agonists), and presence of some of the metabolic traits among some lipodystrophies. We propose the functional failure of an organ, in this case, the adipose tissue as a model to interpret its manifestations and to reconcile some of the apparent paradox. A cornerstone of this model is the failure of the adipose tissue to buffer postprandial lipids. In addition, homeostatic feedback loops guide physiological and pathological adipose tissue activities. Fat turnover is determined by a complex equilibrium in which insulin is a main factor but not the only one. Chronically inadequate energy balance may be a key factor, stressing the system. In this situation, an adipose tissue functional failure occurs resulting in changes in systemic energy delivery, impaired glucose consumption and activation of self-regulatory mechanisms that extend their influence to whole body homeostasis system. These include changes in adipokines secretion and vascular effects. The functional capacity of the adipose tissue varies among subjects explaining the incomplete overlapping among the metabolic syndrome and obesity. Variations at multiple gene loci will be partially responsible for these interindividual differences. Two of those candidate genes, the adiponectin (APM1) and the perilipin (PLIN) genes, are discussed in more detail.
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Affiliation(s)
- Martin Laclaustra
- Nutrition and Genomics Laboratory, JM-USDA-HNRCA at Tufts University, 711 Washington Street, Boston, MA 02111, USA
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Kim J, Saidel GM, Cabrera ME. Multi-scale computational model of fuel homeostasis during exercise: effect of hormonal control. Ann Biomed Eng 2006; 35:69-90. [PMID: 17111212 DOI: 10.1007/s10439-006-9201-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Accepted: 09/08/2006] [Indexed: 11/28/2022]
Abstract
A mathematical model of the whole-body metabolism is developed to predict fuel homeostasis during exercise by using hormonal control over cellular metabolic processes. The whole body model is composed of seven tissue compartments: brain, heart, liver, GI (gastrointestinal) tract, skeletal muscle, adipose tissue, and "other tissues". Each tissue compartment is described by dynamic mass balances and major cellular metabolic reactions. The glucagon-insulin controller is incorporated into the whole body model to predict hormonal changes during exercise. Moderate [150 W power output at 60% of peak oxygen consumption (VO(2max))] exercise for 60 min was implemented by increasing ATP utilization rates in heart and skeletal muscle. Arterial epinephrine level was given as an input function, which directly affects heart and skeletal muscle metabolism and indirectly other tissues via glucagon-insulin controller. Model simulations were validated with experimental data from human exercise studies. The exercise induced changes in hormonal signals modulated metabolic flux rates of different tissues in a coordinated way to achieve glucose homeostasis, demonstrating the efficacy of hormonal control over cellular metabolic processes. From experimental measurements of whole body glucose balance and arterial substrate concentrations, this model could predict the dynamic changes of hepatic glycogenolysis and gluconeogenesis, which are not easy to measure experimentally, suggesting the higher contribution of glycogenolysis ( approximately 75%). In addition, it could provide dynamic information on the relative contribution of carbohydrates and lipids for fuel oxidation in skeletal muscle. Model simulations indicate that external fuel supplies from other tissue/organ systems to skeletal muscle become important for prolonged exercise emphasizing the significance of interaction among tissues. In conclusion, this model can be used as a valuable complement to experimental studies due to its ability to predict what is difficult to measure directly, and usefulness to provide information about dynamic behaviors.
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Affiliation(s)
- Jaeyeon Kim
- Department of Biomedical Engineering, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
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