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Nørholm A, Kjær IG, Søndergaard E, Nellemann B, Nielsen S, Lebeck J. Glycerol Handling in Paired Visceral and Subcutaneous Adipose Tissues in Women with Normal Weight and Upper-Body Obesity. Int J Mol Sci 2024; 25:9008. [PMID: 39201693 PMCID: PMC11354935 DOI: 10.3390/ijms25169008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Revised: 07/29/2024] [Accepted: 07/30/2024] [Indexed: 09/03/2024] Open
Abstract
In adipose tissue, reduced expression of the glycerol channel aquaporin 7 (AQP7) has been associated with increased accumulation of triglyceride. The present study determines the relative protein abundances of lipolytic enzymes, AQP7, and cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) in paired mesenteric and omental visceral adipose tissue (VAT) and abdominal and femoral subcutaneous adipose tissue (SAT) in women with either normal weight or upper-body obesity. No differences in the expression of hormone-sensitive lipase (HSL) or AQP7 were found between the two groups in the four depots. The expression of adipocyte triglyceride lipase (ATGL) and HSL were higher in omental VAT and femoral SAT than in mesenteric VAT in both groups of women. Similarly, AQP7 expression was higher in omental VAT than in mesenteric VAT. The expression of PEPCK-C was lower in omental VAT than in femoral SAT. No correlation between the expression of AQP7 and the mean adipocyte size was observed; however, the expression of PEPCK-C positively correlated with the mean adipocyte size. In conclusion, a depot-specific protein expression pattern was found for ATGL, HSL, AQP7, and PEPCK-C. The expression pattern supports that the regulation of AQP7 protein expression is at least in part linked to the lipolytic rate. Furthermore, the results support that the synthesis of glycerol-3-phosphate via glyceroneogenesis contributes to regulating triglyceride accumulation in white adipose tissue in women.
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Affiliation(s)
- Anne Nørholm
- Department of Biomedicine, Aarhus University, 8200 Aarhus, Denmark; (A.N.)
| | | | - Esben Søndergaard
- Steno Diabetes Center Aarhus, Aarhus University Hospital, 8200 Aarhus, Denmark; (E.S.); (S.N.)
| | - Birgitte Nellemann
- Center for Treatment of Rheumatic and Musculoskeletal Diseases (REMEDY), Diakonhjemmet Hospital, 0370 Oslo, Norway
| | - Søren Nielsen
- Steno Diabetes Center Aarhus, Aarhus University Hospital, 8200 Aarhus, Denmark; (E.S.); (S.N.)
- Department of Clinical Medicine, Aarhus University, 8000 Aarhus, Denmark
| | - Janne Lebeck
- Department of Biomedicine, Aarhus University, 8200 Aarhus, Denmark; (A.N.)
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2
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Risikesan J, Heebøll S, Kumarathas I, Søndergaard E, Johansen RF, Ringgaard S, Aagaard NK, Sandahl TD, Villadsen GE, Gormsen LC, Frystyk J, Jensen MD, Grønbæk H, Nielsen S. Similar insulin regulation of splanchnic FFA and VLDL-TG in men with nonalcoholic hepatic steatosis and steatohepatitis. J Lipid Res 2024; 65:100580. [PMID: 38901559 PMCID: PMC11301221 DOI: 10.1016/j.jlr.2024.100580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 06/10/2024] [Accepted: 06/14/2024] [Indexed: 06/22/2024] Open
Abstract
This study aimed to determine whether obese men with nonalcoholic fatty liver disease (NAFLD) display differences between those with simple steatosis versus steatohepatitis (NASH) in splanchnic and hepatic FFA and VLDL-triglycerides (VLDL-TG) balances. The study involved 17 obese men with biopsy-proven NAFLD (9 with NASH and 8 with simple steatosis). We used hepatic vein catheterization in combination with [3H]palmitate and [14C]VLDL-TG tracers to measure splanchnic palmitate and VLDL-TG uptake and release rates during basal and hyperinsulinemic conditions. Indocyanine green was used to measure splanchnic plasma flow. Splanchnic palmitate uptake was similar in the two groups and significantly reduced during hyperinsulinemia (NASH: 62 (48-77) versus 38 (18-58) μmol/min; simple steatosis: 62 (46-78) versus 45 (25-65) μmol/min, mean (95% CI), basal versus clamp periods, respectively, P = 0.02 time-effect). Splanchnic palmitate release was also comparable between groups and nonsignificantly diminished during hyperinsulinemia. The percent palmitate delivered to the liver originating from visceral adipose tissue lipolysis was similar and unchanged by hyperinsulinemia. Splanchnic uptake and release of VLDL-TG were similar between groups. Hyperinsulinemia suppressed VLDL-TG release (P <0.05 time-effect) in both groups. Insulin-mediated glucose disposal was similar in the two groups (P = 0.54). Obese men with NASH and simple steatosis have similar splanchnic uptake and release of FFA and VLDL-TG and a similar proportion of FFA from visceral adipose tissue lipolysis delivered to the liver. These results demonstrate that the splanchnic balances of FFA and VLDL-TG do not differ between obese men with NASH and those with simple steatosis.
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Affiliation(s)
| | - Sara Heebøll
- Steno Diabetes Center Aarhus, Aarhus University Hospital (AUH), Aarhus, Denmark; Department of Endocrinology and Internal Medicine, AUH, Aarhus, Denmark
| | | | - Esben Søndergaard
- Steno Diabetes Center Aarhus, Aarhus University Hospital (AUH), Aarhus, Denmark
| | - Rakel F Johansen
- Steno Diabetes Center Aarhus, Aarhus University Hospital (AUH), Aarhus, Denmark
| | | | - Niels K Aagaard
- Department of Hepatology and Gastroenterology, AUH, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Thomas D Sandahl
- Department of Hepatology and Gastroenterology, AUH, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Gerda E Villadsen
- Department of Hepatology and Gastroenterology, AUH, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Lars C Gormsen
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Nuclear Medicine and PET Centre, AUH, Aarhus, Denmark
| | - Jan Frystyk
- Department of Endocrinology, Odense University Hospital, Odense, Denmark
| | | | - Henning Grønbæk
- Department of Hepatology and Gastroenterology, AUH, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Søren Nielsen
- Steno Diabetes Center Aarhus, Aarhus University Hospital (AUH), Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
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3
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Ye RZ, Richard G, Gévry N, Tchernof A, Carpentier AC. Fat Cell Size: Measurement Methods, Pathophysiological Origins, and Relationships With Metabolic Dysregulations. Endocr Rev 2022; 43:35-60. [PMID: 34100954 PMCID: PMC8755996 DOI: 10.1210/endrev/bnab018] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Indexed: 11/19/2022]
Abstract
The obesity pandemic increasingly causes morbidity and mortality from type 2 diabetes, cardiovascular diseases and many other chronic diseases. Fat cell size (FCS) predicts numerous obesity-related complications such as lipid dysmetabolism, ectopic fat accumulation, insulin resistance, and cardiovascular disorders. Nevertheless, the scarcity of systematic literature reviews on this subject is compounded by the use of different methods by which FCS measurements are determined and reported. In this paper, we provide a systematic review of the current literature on the relationship between adipocyte hypertrophy and obesity-related glucose and lipid dysmetabolism, ectopic fat accumulation, and cardiovascular disorders. We also review the numerous mechanistic origins of adipocyte hypertrophy and its relationship with metabolic dysregulation, including changes in adipogenesis, cell senescence, collagen deposition, systemic inflammation, adipokine secretion, and energy balance. To quantify the effect of different FCS measurement methods, we performed statistical analyses across published data while controlling for body mass index, age, and sex.
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Affiliation(s)
- Run Zhou Ye
- Division of Endocrinology, Department of Medicine, Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Gabriel Richard
- Division of Endocrinology, Department of Medicine, Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Nicolas Gévry
- Department of Biology, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - André Tchernof
- Québec Heart and Lung Research Institute, Laval University, Québec, Québec, Canada
| | - André C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
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4
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Abstract
Although visceral fat is strongly correlated with the metabolic complications of obesity, the existing data indicate it is not the cause of these complications. Excess release of free fatty acids (FFA) from adipose tissue lipolysis can account for a sizable portion of the metabolic complications of obesity. In humans, upper-body subcutaneous adipose tissue accounts for most systemic FFA, whereas visceral fat contributes a modest portion of the excess amount to which the liver is exposed. This pattern is maintained in upper-body/visceral obesity, except that greater amounts of visceral fat expose the liver to more FFA from visceral adipose tissue lipolysis.
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Affiliation(s)
- Michael D Jensen
- Department of Endocrinology, Metabolism, Diabetes, & Nutrition, Mayo Clinic, 200 First Street Southwest, Room 5-194 Joseph, Rochester, MN 55905, USA.
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5
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Johansen RF, Søndergaard E, Linnebjerg H, Garhyan P, Lam ECQ, Porksen N, Jacober SJ, Nielsen S. Attenuated suppression of lipolysis explains the increases in triglyceride secretion and concentration associated with basal insulin peglispro relative to insulin glargine treatment in patients with type 1 diabetes. Diabetes Obes Metab 2018; 20:419-426. [PMID: 28817248 DOI: 10.1111/dom.13087] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 08/04/2017] [Accepted: 08/12/2017] [Indexed: 01/11/2023]
Abstract
AIMS To test the hypothesis that, as well as lowering weight and increasing plasma triglyceride (TG) levels and hepatic fat compared with insulin glargine (GL) in patients with type 1 diabetes, the attenuated peripheral effects of basal insulin peglispro (BIL) may include increased free fatty acid flux to the liver, causing increased very-low-density lipoprotein (VLDL)-TG secretion and lipid oxidation, and decreased TG adipose tissue deposition. METHODS In this open-label, randomized, 2-period crossover study, 14 patients with type 1 diabetes received once-daily, individualized, stable BIL or GL doses for 3 weeks. Palmitate flux was assessed using [9,10-3 H]palmitate infusion. VLDL-TG secretion, clearance and oxidation rate were assessed using primed-constant infusion of ex vivo labelled [1-14 C]VLDL-TG, while VLDL-TG storage rate was assessed using [9,10-3 H]VLDL-TG bolus injection. RESULTS The VLDL-TG concentration and secretion rate, and palmitate flux were statistically significantly higher during BIL than during GL treatment (58%, 51% and 35%, respectively). The ratios of least squares (LS) geometric means for VLDL-TG clearance and oxidation were 0.92 (95% confidence interval [CI] 0.72, 1.17) and 1.31 (95% CI 0.91, 1.90), respectively. The difference in LS means for VLDL-TG storage rate was -0.36 (95% CI -0.83, 0.12). CONCLUSIONS BIL-treated patients had higher effective lipolysis, VLDL-TG secretion and VLDL-TG concentration compared with GL-treated patients, explaining the increased plasma TG concentrations reported previously. Data support attenuated effects of BIL on lipolysis, in addition to the recently described hepato-preferential glucodynamic effects.
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Affiliation(s)
- Rakel F Johansen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Esben Søndergaard
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | | | | | - Eric C Q Lam
- Formerly of Eli Lilly and Company, Singapore, Singapore
| | - Niels Porksen
- Formerly of Eli Lilly and Company, Indianapolis, Indiana
| | | | - Søren Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
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6
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Søndergaard E, Nielsen S. VLDL triglyceride accumulation in skeletal muscle and adipose tissue in type 2 diabetes. Curr Opin Lipidol 2018; 29:42-47. [PMID: 29135689 DOI: 10.1097/mol.0000000000000471] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW Insulin resistance is closely linked to accumulation of lipid outside adipose tissue (ectopic fat storage). VLDL particles transport lipids from the liver to peripheral tissues. However, whether abnormalities in VLDL-triglyceride storage in muscle and adipose tissue exist in type 2 diabetes has previously been unknown, primarily because of methodological difficulties. Here, we review recent research on VLDL-triglyceride storage. RECENT FINDINGS In a recent study, men with type 2 diabetes had increased skeletal muscle VLDL-triglyceride storage compared to weight-matched nondiabetic men, potentially leading to intramyocellular triglyceride accumulation. In contrast, studies of adipose tissue VLDL-triglyceride storage have shown similar storage capacity in men with and without diabetes, both in the postabsorptive and the postprandial period. In the initial submission, studies have failed to show associations between lipoprotein lipase activity, considered the rate-limiting step in storage of lipids from lipoproteins, and VLDL-TG storage in both muscle and adipose tissue. SUMMARY Differences in muscle VLDL-triglyceride storage may lead to ectopic fat storage and contribute to the development of type 2 diabetes, whereas the ability to store VLDL-triglyceride in adipose tissue is preserved in type 2 diabetes.
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Affiliation(s)
- Esben Søndergaard
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus C
- Danish Diabetes Academy, Odense University Hospital, Odense C, Denmark
| | - Søren Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus C
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Søndergaard E, Johansen RF, Jensen MD, Nielsen S. Postprandial VLDL-TG metabolism in type 2 diabetes. Metabolism 2017; 75:25-35. [PMID: 28964326 DOI: 10.1016/j.metabol.2017.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/26/2017] [Accepted: 07/05/2017] [Indexed: 01/22/2023]
Abstract
BACKGROUND Type 2 diabetes is associated with excess postprandial lipemia due to accumulation of chylomicrons and VLDL particles. This is a risk factor for development of cardiovascular disease. However, whether the excess lipemia is associated with an impaired suppression of VLDL-TG secretion and/or reduced clearance into adipose tissue is unknown. OBJECTIVE We measured the postprandial VLDL-TG secretion, clearance and adipose tissue storage to test the hypothesis that impaired postprandial suppression of VLDL-TG secretion, combined with impaired VLDL-TG storage in adipose tissue, is associated with excess postprandial lipemia. DESIGN We studied 11 men with type 2 diabetes and 10 weight-matched non-diabetic men using ex-vivo labeled VLDL-TG tracers during an oral high-fat mixed-meal tolerance test to measure postprandial VLDL-TG secretion, clearance and storage. In addition, adipose tissue biopsies were analyzed for LPL activity and cellular storage factors. RESULTS Men with type 2 diabetes had greater postprandial VLDL-TG concentration compared to non-diabetic men. However, postprandial VLDL-TG secretion rate was similar in the two groups with equal suppression of VLDL-TG secretion rate (≈50%) and clearance rate. In addition, postprandial VLDL-TG storage was similar in the two groups in both upper body and lower body subcutaneous adipose tissue. CONCLUSIONS Despite greater postprandial VLDL-TG concentration, men with type 2 diabetes have similar postprandial suppression of VLDL-TG secretion and a similar ability to store VLDL-TG in adipose tissue compared to non-diabetic men. This may indicate that abnormalities in postprandial VLDL-TG metabolism are a consequence of obesity/insulin resistance more than a result of type 2 diabetes per se.
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Affiliation(s)
- Esben Søndergaard
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark; Danish Diabetes Academy, Odense University Hospital, Kløvervænget 10, Entrance 112, 3rd floor, 5000 Odense C, Denmark; Endocrine Research Unit, Mayo Clinic, 1216 2nd St SW, Rochester, MN 55902, USA.
| | - Rakel Fuglsang Johansen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark
| | - Michael D Jensen
- Endocrine Research Unit, Mayo Clinic, 1216 2nd St SW, Rochester, MN 55902, USA
| | - Søren Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark
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8
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Spalding KL, Bernard S, Näslund E, Salehpour M, Possnert G, Appelsved L, Fu KY, Alkass K, Druid H, Thorell A, Rydén M, Arner P. Impact of fat mass and distribution on lipid turnover in human adipose tissue. Nat Commun 2017; 8:15253. [PMID: 28534500 PMCID: PMC5457499 DOI: 10.1038/ncomms15253] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 03/13/2017] [Indexed: 12/13/2022] Open
Abstract
Differences in white adipose tissue (WAT) lipid turnover between the visceral (vWAT) and subcutaneous (sWAT) depots may cause metabolic complications in obesity. Here we compare triglyceride age and, thereby, triglyceride turnover in vWAT and sWAT biopsies from 346 individuals and find that subcutaneous triglyceride age and storage capacity are increased in overweight or obese individuals. Visceral triglyceride age is only increased in excessively obese individuals and associated with a lower lipid removal capacity. Thus, although triglyceride storage capacity in sWAT is higher than in vWAT, the former plateaus at substantially lower levels of excess WAT mass than vWAT. In individuals with central or visceral obesity, lipid turnover is selectively increased in vWAT. Obese individuals classified as ‘metabolically unhealthy' (according to ATPIII criteria) who have small subcutaneous adipocytes exhibit reduced triglyceride turnover. We conclude that excess WAT results in depot-specific differences in lipid turnover and increased turnover in vWAT and/or decreased turnover in sWAT may result in metabolic complications of overweight or obesity. Lipid turnover in tissues can be calculated from ratios of different carbon isotopes. Here the authors use this approach to study lipid turnover in two distinct adipose tissue depots and find that, in obese individuals, visceral fat is more lipolytic than subcutaneous fat.
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Affiliation(s)
- Kirsty L Spalding
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm SE-17177, Sweden.,Metabolism Unit and KI/AZ Integrated Cardio Metabolic Center, Department of Medicine, Karolinska University Hospital, Karolinska Institutet, Stockholm SE 17176, Sweden
| | - Samuel Bernard
- Institut Camille Jordan, University of Lyon, Villeurbanne F 69622, France
| | - Erik Näslund
- Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, Stockholm SE 18288, Sweden
| | - Mehran Salehpour
- Department of Physics and Astronomy, Ion Physics, Uppsala University, Uppsala SE-75120, Sweden
| | - Göran Possnert
- Department of Physics and Astronomy, Ion Physics, Uppsala University, Uppsala SE-75120, Sweden
| | - Lena Appelsved
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm SE-17177, Sweden
| | - Keng-Yeh Fu
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm SE-17177, Sweden
| | - Kanar Alkass
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm SE-17177, Sweden
| | - Henrik Druid
- Department of Oncology-Pathology, Karolinska Institutet, Stockholm SE 17177, Sweden.,Department of Forensic Medicine, The National Board of Forensic Medicine, Stockholm SE 11120, Sweden
| | - Anders Thorell
- Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, Stockholm SE 18288, Sweden.,Department of Surgery, Ersta Hospital, Karolinska Institutet, Stockholm SE 11691, Sweden
| | - Mikael Rydén
- Department of Medicine, Karolinska University Hospital, Karolinska Institutet, Stockholm SE-141 86, Sweden
| | - Peter Arner
- Department of Medicine, Karolinska University Hospital, Karolinska Institutet, Stockholm SE-141 86, Sweden
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9
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Søndergaard E, Andersen IR, Sørensen LP, Gormsen LC, Nielsen S. Lipoprotein lipase activity does not predict very low-density lipoprotein-triglyceride fatty acid oxidation during exercise. Scand J Med Sci Sports 2017; 27:474-481. [PMID: 28207959 DOI: 10.1111/sms.12859] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2017] [Indexed: 11/30/2022]
Abstract
Exercise lowers plasma triglyceride levels, but the physiological mechanisms remain not fully elucidated. Lipoprotein lipase (LPL) is a key enzyme in facilitating fatty acid uptake from lipoproteins. As exercise increases the efficiency of very low-density lipoprotein-triglyceride (VLDL-TG) oxidation, we hypothesized that muscle LPL activity would be a rate-limiting step and predict VLDL-TG Fatty acids oxidation during exercise. Sixteen healthy, lean subjects (eight men and eight women) were examined before and during an acute exercise bout (90 minutes at 50% of VO2-max). Heparin-releasable LPL activity was measured in muscle and adipose tissue biopsies. Breath 14 CO2 was measured after a primed-constant infusion of ex vivo labeled [14 C]-triolein VLDL-TG. Fractional VLDL-TG storage was measured in adipose tissue biopsies. Exercise did not affect muscle LPL activity (P=.30). No association was observed between muscle LPL activity and VLDL-TG oxidation, neither in the basal state (P=.17) nor during exercise (P=.83). Exercise did not affect upper body or lower body adipose tissue LPL activity (both P=.92). The basal adipose tissue fractional VLDL-TG storage (abdominal.13%±9%; femoral 17%±10% (P=.18)) was not associated with upper body (P=.56) or lower body (P=.44) subcutaneous adipose tissue LPL activity. Muscle LPL activity does not predict VLDL-TG oxidation during rest or exercise. In addition, adipose tissue LPL activity was not associated with VLDL-TG storage during rest. This suggests that LPL activity is present in excess of what is required to facilitate lipid uptake for oxidation during both rest and exercise.
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Affiliation(s)
- E Søndergaard
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark.,The Danish Diabetes Academy, Odense, Denmark
| | - I R Andersen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - L P Sørensen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - L C Gormsen
- Department of Nuclear Medicine and PET center, Aarhus University Hospital, Aarhus, Denmark
| | - S Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
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10
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Abstract
PURPOSE OF REVIEW Plasma free fatty acids (FFA) are major substrates for hepatic VLDL-triglycerides (VLDL-TG) production. In addition, it is a common belief that VLDL-TG production is a substrate driven process primarily determined by systemic FFA delivery. This review summarizes recent research of our understanding of the regulation of VLDL-TG production. RECENT FINDINGS Recent studies have shown that increasing FFA flux is not inevitably associated with increased VLDL-TG production. Exercise induced increase in FFA flux resulting in unchanged VLDL-TG production in lean patients as well as in obese patients with increased hepatic fat despite exercise reduced hepatic fat content. With respect to the other inseparable conditions of insulin resistance and hyperinsulinemia, recent studies demonstrate that increased hepatic VLDL-TG production precedes the insulin resistance-associated impairment of the regulation of hepatic glucose production, whereas isolated chronic hyperinsulinemia (insulinoma) was not associated with increased VLDL-TG production. Insulin has been shown to have acute potent temporary suppressing effect on VLDL-TG production and new data demonstrates that increased glucagon reduces VLDL-TG production. Finally, recent studies indicate that sex hormones, oestrogen and testosterone, have no or very modest impact on VLDL-TG production. SUMMARY Regulation of hepatic VLDL-TG production involves interplay between systemic FFA delivery, hormonal, and nutritional factors that act in concert with hepatic fatty acid handling to regulate short-term and long-term VLDL-TG production. The results of recent studies underscore that our current understanding of these relationships is complex and needs further research.
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Affiliation(s)
- Søren Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
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11
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Androutsos O, Grammatikaki E, Moschonis G, Roma-Giannikou E, Chrousos GP, Manios Y, Kanaka-Gantenbein C. Neck circumference: a useful screening tool of cardiovascular risk in children. Pediatr Obes 2012; 7:187-95. [PMID: 22505226 DOI: 10.1111/j.2047-6310.2012.00052.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 12/13/2011] [Accepted: 01/26/2012] [Indexed: 01/07/2023]
Abstract
OBJECTIVE Early identification of cardiovascular risk factors consists an essential target for public health. The current study aims to examine the association between neck circumference and several cardiovascular risk factors and to compare it with well-established anthropometric indices. METHODS Demographic, anthropometric (body weight and height, waist, hip and neck circumference [WC, HC and NC, respectively]), biochemical (total cholesterol, high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol, triglycerides [TG], fasting plasma glucose and serum insulin), clinical (pubertal stage, systolic and diastolic blood pressure [SBP and DBP, respectively]) and lifestyle (dietary intake, physical activity level) data were collected from 324 children (51.5% boys; 48.5% girls) aged 9-13 in Greece. Body mass index z-score (BMI z-score), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), homeostasis model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI) and fasting glucose to insulin ratio (FGIR) were calculated. RESULTS All indices (BMI z-score, NC, WC, HC, WHR and WHtR) were correlated with SBP, HDL and insulin-related indices (insulin, HOMA-IR, QUICKI and FGIR) and all indices except WHR with TG. LDL was correlated with BMI z-score, WC, WHR and WHtR, whereas DBP was correlated with BMI z-score, WC, HC and WHtR. In multivariate analysis, HDL, TG, SBP, insulin, HOMA-IR, QUICKI and FGIR were associated with all anthropometric indices; DBP with WC, HC, NC and WHtR; LDL with BMI z-score, WC, HC and WHtR. CONCLUSIONS NC is associated with most cardiovascular disease risk factors. These associations are comparable with those observed for BMI z-score, WC, HC, WHR and WHtR. NC could be a simple, alternative screening tool of cardiovascular risk in children.
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Affiliation(s)
- O Androutsos
- First Department of Paediatrics, University of Athens, Aghia Sophia Children's Hospital, Athens, Greece.
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12
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Votruba SB, Jensen MD. Short-term regional meal fat storage in nonobese humans is not a predictor of long-term regional fat gain. Am J Physiol Endocrinol Metab 2012; 302:E1078-83. [PMID: 22338076 PMCID: PMC3361980 DOI: 10.1152/ajpendo.00414.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although body fat distribution strongly predicts metabolic health outcomes related to excess weight, little is known about the factors an individual might exhibit that predict a particular fat distribution pattern. We utilized the meal fatty acid tracer-adipose biopsy technique to assess upper and lower body subcutaneous (UBSQ and LBSQ, respectively) meal fat storage in lean volunteers who then were overfed to gain weight. Meal fatty acid storage in UBSQ and LBSQ adipose tissue, as well as daytime substrate oxidation (indirect calorimetry), was measured in 28 nonobese volunteers [n = 15 men, body mass index = 22.1 ± 2.5 (SD)] before and after an ∼8-wk period of supervised overfeeding (weight gain = 4.6 ± 2.2 kg, fat gain = 3.8 ± 1.7 kg). Meal fat storage (mg/g adipose tissue lipid) in UBSQ (visit 1: 0.78 ± 0.34 and 1.04 ± 0.71 for women and men, respectively, P = 0.22; visit 2: 0.71 ± 0.24 and 0.90 ± 0.37 for women and men, respectively, P = 0.08) and LBSQ (visit 1: 0.60 ± 0.23 and 0.48 ± 0.29 for women and men, respectively, P = 0.25; visit 2: 0.62 ± 0.24 and 0.65 ± 0.23 for women and men, respectively, P = 0.67) adipose tissue did not differ between men and women at either visit. Fractional meal fatty acid storage in UBSQ (0.31 ± 0.15) or LBSQ (0.19 ± 0.13) adipose tissue at visit 1 did not predict the percent change in regional body fat in response to overfeeding. These data indicate that meal fat uptake trafficking in the short term (24 h) is not predictive of body fat distribution patterns. In general, UBSQ adipose tissue appears to be a favored depot for meal fat deposition in both sexes, and redistribution of meal fatty acids likely takes place at later time periods.
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Jeppesen J, Kiens B. Regulation and limitations to fatty acid oxidation during exercise. J Physiol 2012; 590:1059-68. [PMID: 22271865 DOI: 10.1113/jphysiol.2011.225011] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Fatty acids (FAs) as fuel for energy utilization during exercise originate from different sources: FAs transported in the circulation either bound to albumin or as triacylglycerol (TG) carried by very low density lipoproteins and FAs from lipolysis of muscle TG stores. Despite a high rate of energy expenditure during high intensity exercise the total FA oxidation is suppressed to below that observed during moderate intensity exercise. Although this has been known for many years, the mechanisms behind this phenomenon are still not fully elucidated. A failure of adipose tissue to deliver sufficient FAs to exercising muscle has been proposed, but evidence is emerging that factors within the muscle might be of more importance. The high rate of glycolysis during high intensity exercise might be the 'driving force' via the increased production of acetyl-CoA, which in turn is trapped by carnitine. This will lead to decreased availability of free carnitine for long chain FA transport into mitochondria. This review summarizes our present view on how FA metabolism is regulated during exercise with a special focus on the limitations in FA oxidation in the transition from moderate to high intensity exercise in humans.
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Affiliation(s)
- Jacob Jeppesen
- Molecular Physiology Group, Department of Exercise and Sport Sciences, University of Copenhagen, Denmark
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