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Hjelholt AJ, Charidemou E, Griffin JL, Pedersen SB, Gudiksen A, Pilegaard H, Jessen N, Møller N, Jørgensen JOL. Insulin resistance induced by growth hormone is linked to lipolysis and associated with suppressed pyruvate dehydrogenase activity in skeletal muscle: a 2 × 2 factorial, randomised, crossover study in human individuals. Diabetologia 2020; 63:2641-2653. [PMID: 32945898 DOI: 10.1007/s00125-020-05262-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 07/15/2020] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS Growth hormone (GH) causes insulin resistance that is linked to lipolysis, but the underlying mechanisms are unclear. We investigated if GH-induced insulin resistance in skeletal muscle involves accumulation of diacylglycerol (DAG) and ceramide as well as impaired insulin signalling, or substrate competition between fatty acids and glucose. METHODS Nine GH-deficient male participants were randomised and examined in a 2 × 2 factorial design with and without administration of GH and acipimox (an anti-lipolytic compound). As-treated analyses were performed, wherefore data from three visits from two patients were excluded due to incorrect GH administration. The primary outcome was insulin sensitivity, expressed as the AUC of the glucose infusion rate (GIRAUC), and furthermore, the levels of DAGs and ceramides, insulin signalling and the activity of the active form of pyruvate dehydrogenase (PDHa) were assessed in skeletal muscle biopsies obtained in the basal state and during a hyperinsulinaemic-euglycaemic clamp (HEC). RESULTS Co-administration of acipimox completely suppressed the GH-induced elevation in serum levels of NEFA (GH versus GH+acipimox, p < 0.0001) and abrogated GH-induced insulin resistance (mean GIRAUC [95% CI] [mg min-1 kg-1] during the HEC: control, 595 [493, 718]; GH, 468 [382, 573]; GH+acipimox, 654 [539, 794]; acipimox, 754 [618, 921]; GH vs GH+acipimox: p = 0.004). GH did not significantly change either the accumulation of DAGs and ceramides or insulin signalling in skeletal muscle, but GH antagonised the insulin-stimulated increase in PDHa activity (mean ± SEM [% from the basal state to the HEC]: control, 47 ± 19; GH, -15 ± 21; GH+acipimox, 3 ± 21; acipimox, 57 ± 22; main effect: p = 0.02). CONCLUSIONS/INTERPRETATION GH-induced insulin resistance in skeletal muscle is: (1) causally linked to lipolysis; (2) not associated with either accumulation of DAGs and ceramides or impaired insulin signalling; (3) likely to involve substrate competition between glucose and lipid intermediates. TRIAL REGISTRATION ClinicalTrials.gov NCT02782208 FUNDING: The work was supported by the Grant for Growth Innovation (GGI), which was funded by Merck KGaA, Darmstadt, Germany. Graphical abstract.
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Affiliation(s)
- Astrid J Hjelholt
- Medical Research Laboratory, Department of Clinical Medicine, Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus N, Denmark.
- Department of Clinical Pharmacology, Aarhus University Hospital, Aarhus C, Denmark.
| | - Evelina Charidemou
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Julian L Griffin
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Steen B Pedersen
- Medical Research Laboratory, Department of Clinical Medicine, Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus N, Denmark
| | - Anders Gudiksen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Henriette Pilegaard
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Niels Jessen
- Department of Clinical Pharmacology, Aarhus University Hospital, Aarhus C, Denmark
- Steno Diabetes Centre Aarhus, Aarhus University Hospital, Aarhus N, Denmark
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Niels Møller
- Medical Research Laboratory, Department of Clinical Medicine, Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus N, Denmark
| | - Jens O L Jørgensen
- Medical Research Laboratory, Department of Clinical Medicine, Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus N, Denmark
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Fujitani M, Matsumura S, Masuda D, Yamashita S, Fushiki T, Inoue K. CD36, but not GPR120, is required for efficient fatty acid utilization during endurance exercise. Biosci Biotechnol Biochem 2014; 78:1871-8. [PMID: 25070011 DOI: 10.1080/09168451.2014.940835] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Fatty acids (FA) are an important energy source during exercise. In addition to its role as an energy supply for skeletal muscle, FA may activate signaling pathways that regulate gene expression. FA translocase/cluster of differentiation 36 (CD36) and G protein-coupled receptor GPR120 are long-chain FA receptors. In this study, we investigated the impact of CD36 or GPR120 deletion on energy metabolism during exercise. CD36 has been reported to facilitate cellular transport and oxidation of FA during endurance exercise. We show that CD36 deletion decreased exogenous FA oxidation during exercise, using a combination of (13)C-labeled FA oxidation measurement and indirect calorimetry. In contrast, GPR120 deletion had no observable effect on energy metabolism during exercise. Our results further substantiate that CD36-mediated FA transport plays an essential role in efficient FA oxidation during exercise.
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Affiliation(s)
- Mina Fujitani
- a Laboratory of Nutrition Chemistry, Graduate School of Agriculture , Kyoto University , Sakyou-ku , Japan
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Chabowski A, Górski J, Glatz JFC, P Luiken JJF, Bonen A. Protein-mediated Fatty Acid Uptake in the Heart. Curr Cardiol Rev 2011; 4:12-21. [PMID: 19924273 PMCID: PMC2774581 DOI: 10.2174/157340308783565429] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 06/18/2007] [Accepted: 06/22/2007] [Indexed: 12/22/2022] Open
Abstract
Long chain fatty acids (LCFAs) provide 70-80% of the energy for cardiac contractile activity. LCFAs are also essential for many other cellular functions, such as transcriptional regulation of proteins involved in lipid metabolism, modulation of intracellular signalling pathways, and as substrates for membrane constituents. When LCFA uptake exceeds the capacity for their cardiac utilization, the intracellular lipids accumulate and are thought to contribute to contractile dysfunction, arrhythmias, cardiac myocyte apoptosis and congestive heart failure. Moreover, increased cardiac myocyte triacylglycerol, diacylglycerol and ceramide depots are cardinal features associated with obesity and type 2 diabetes. In recent years considerable evidence has accumulated to suggest that, the rate of entry of long chain fatty acids (LCFAs) into the cardiac myocyte is a key factor contributing to a) regulating cardiac LCFA metabolism and b) lipotoxicity in the obese and diabetic heart. In the present review we i) examine the evidence indicating that LCFA transport into the heart involves a protein-mediated mechanism, ii) discuss the proteins involved in this process, including FAT/CD36, FABPpm and FATP1, iii) discuss the mechanisms involved in regulating LCFA transport by some of these proteins (including signaling pathways), as well as iv) the possible interactions of these proteins in regulating LCFA transport into the heart. In addition, v) we discuss how LCFA transport and transporters are altered in the obese/diabetic heart.
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Affiliation(s)
- Adrian Chabowski
- Department of Physiology, Medical University of Bialystok, 15-089 Bialystok, Poland
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Differential effects of saturated versus unsaturated dietary fatty acids on weight gain and myocellular lipid profiles in mice. Nutr Diabetes 2011; 1:e11. [PMID: 23449423 PMCID: PMC3302136 DOI: 10.1038/nutd.2011.7] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Objective: In conditions of continuous high-fat (HF) intake, the degree of saturation of the fatty acids (FAs) in the diet might have a crucial role in the onset of obesity and its metabolic complications. In particular, the FA composition of the diet might influence the storage form of lipids inside skeletal muscle. The aim of the present study was to examine whether the FA composition of HF diets differentially affects weight gain and accumulation of myocellular triacylglycerol (TAG) and diacylglycerol (DAG). Furthermore, we examined whether the FA composition of the diet was reflected in the composition of the myocellular lipid intermediates. Design: C57Bl6 mice were fed HF diets (45% energy) mainly containing palm oil (PO), cocoa butter (CB), olive oil (OO) or safflower oil (SO; n=6 per group) for 8 weeks. A low-fat diet (10% energy, PO) was used as control. Body weight was monitored weekly. At the end of the dietary intervention, myocellular TAG and DAG content and profiles were measured. Results: We here show that HF_CB prevented weight gain after 8 weeks of HF feeding. Furthermore, the HF diet rich in SO prevented the accumulation of both myocellular TAG and DAG. Interestingly, the FA composition of DAG and TAG in skeletal muscle was a reflection of the dietary FA composition. Conclusion: Already after a relatively short period, the dietary FA intake relates to the FA composition of the lipid metabolites in the muscle. A diet rich in polyunsaturated FAs seems to prevent myocellular lipid accumulation.
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Liu L, Yu S, Khan RS, Ables GP, Bharadwaj KG, Hu Y, Huggins LA, Eriksson JW, Buckett LK, Turnbull AV, Ginsberg HN, Blaner WS, Huang LS, Goldberg IJ. DGAT1 deficiency decreases PPAR expression and does not lead to lipotoxicity in cardiac and skeletal muscle. J Lipid Res 2011; 52:732-44. [PMID: 21205704 DOI: 10.1194/jlr.m011395] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Diacylglycerol (DAG) acyl transferase 1 (Dgat1) knockout ((-/-)) mice are resistant to high-fat-induced obesity and insulin resistance, but the reasons are unclear. Dgat1(-/-) mice had reduced mRNA levels of all three Ppar genes and genes involved in fatty acid oxidation in the myocardium of Dgat1(-/-) mice. Although DGAT1 converts DAG to triglyceride (TG), tissue levels of DAG were not increased in Dgat1(-/-) mice. Hearts of chow-diet Dgat1(-/-) mice were larger than those of wild-type (WT) mice, but cardiac function was normal. Skeletal muscles from Dgat1(-/-) mice were also larger. Muscle hypertrophy factors phospho-AKT and phospho-mTOR were increased in Dgat1(-/-) cardiac and skeletal muscle. In contrast to muscle, liver from Dgat1(-/-) mice had no reduction in mRNA levels of genes mediating fatty acid oxidation. Glucose uptake was increased in cardiac and skeletal muscle in Dgat1(-/-) mice. Treatment with an inhibitor specific for DGAT1 led to similarly striking reductions in mRNA levels of genes mediating fatty acid oxidation in cardiac and skeletal muscle. These changes were reproduced in cultured myocytes with the DGAT1 inhibitor, which also blocked the increase in mRNA levels of Ppar genes and their targets induced by palmitic acid. Thus, loss of DGAT1 activity in muscles decreases mRNA levels of genes involved in lipid uptake and oxidation.
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Affiliation(s)
- Li Liu
- Division of Preventive Medicine and Nutrition, Columbia University, New York, NY, USA
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Regulation of skeletal muscle oxidative capacity and insulin signaling by the mitochondrial rhomboid protease PARL. Cell Metab 2010; 11:412-26. [PMID: 20444421 PMCID: PMC3835349 DOI: 10.1016/j.cmet.2010.04.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 06/15/2009] [Accepted: 04/07/2010] [Indexed: 12/25/2022]
Abstract
Type 2 diabetes mellitus (T2DM) and aging are characterized by insulin resistance and impaired mitochondrial energetics. In lower organisms, remodeling by the protease pcp1 (PARL ortholog) maintains the function and lifecycle of mitochondria. We examined whether variation in PARL protein content is associated with mitochondrial abnormalities and insulin resistance. PARL mRNA and mitochondrial mass were both reduced in elderly subjects and in subjects with T2DM. Muscle knockdown of PARL in mice resulted in malformed mitochondrial cristae, lower mitochondrial content, decreased PGC1alpha protein levels, and impaired insulin signaling. Suppression of PARL protein in healthy myotubes lowered mitochondrial mass and insulin-stimulated glycogen synthesis and increased reactive oxygen species production. We propose that lower PARL expression may contribute to the mitochondrial abnormalities seen in aging and T2DM.
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Chow L, From A, Seaquist E. Skeletal muscle insulin resistance: the interplay of local lipid excess and mitochondrial dysfunction. Metabolism 2010; 59:70-85. [PMID: 19766267 PMCID: PMC2789850 DOI: 10.1016/j.metabol.2009.07.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 06/02/2009] [Accepted: 07/09/2009] [Indexed: 01/07/2023]
Affiliation(s)
- Lisa Chow
- University of Minnesota Medical School, Minneapolis, MN 55455, United States.
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Scheim DE. Cytotoxicity of unsaturated fatty acids in fresh human tumor explants: concentration thresholds and implications for clinical efficacy. Lipids Health Dis 2009; 8:54. [PMID: 20003514 PMCID: PMC2801488 DOI: 10.1186/1476-511x-8-54] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 12/15/2009] [Indexed: 01/11/2023] Open
Abstract
Background Unsaturated fatty acids (UFAs) exhibit in vitro cytotoxicity against many malignant cell lines and yield decreased cancer incidence and reduced tumor growth in animal models. But clinical and animal studies to date have achieved response using only localized delivery methods such as intratumoral infusion. To explore possibilities for enhanced clinical efficacy, fresh surgical explants of tumors from 22 patients with five malignancies were exposed to γ-linolenic acid (GLA) and α-linolenic acid (ALA) and analyzed with an in vitro chemosensitivity testing system, the Fluorescent Cytoprint Assay (FCA). A total of 282 micro-organ cultures derived from these malignant tumors were exposed to GLA and ALA at different concentrations. Results GLA and ALA exhibited greater than 90% cytotoxicity at a sharp concentration threshold between 500 μM and 1 mM against all but two malignant micro-organ cultures tested in 5-10% serum. In tests using 30-40% serum, GLA and ALA killed tumor at concentrations of 2 mM and above. Conclusions The concentration threshold of 500 μM to 2 mM exhibited for antitumor activity by GLA and ALA is much higher than that observed in most previously reported cell culture studies but consistent with physiological concentrations found to kill tumor clinically and in animals. A mechanism of antitumor activity by unsaturated fatty acids through selective destabilization of the malignant plasma membrane is considered. An oral regimen is proposed for phase I clinical testing that could push the area under the curve for serum concentration of unbound unsaturated fatty acids over time to much higher levels than previously achieved for systemic administration and into the range that could yield antitumor response.
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Francaux M. Toll-like receptor signalling induced by endurance exerciseThis paper is one of a selection of papers published in this Special Issue, entitled 14th International Biochemistry of Exercise Conference – Muscles as Molecular and Metabolic Machines, and has undergone the Journal’s usual peer review process. Appl Physiol Nutr Metab 2009; 34:454-8. [DOI: 10.1139/h09-036] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Toll-like receptors (TLRs) are transmembrane proteins that detect a variety of molecular components mostly derived from microorganisms. TLR2 and TLR4 are amongst others present in liver, adipose tissue, and skeletal muscle. Extracellular long-chain fatty acids bind TLR2 and 4 and induce downstream signalling cascades implicated in cellular stress and inflammatory processes. Evidence indicates that TLR activation by non-esterified fatty acids (NEFAs) may participate in the development of insulin resistance. Exercise seems to induce a downregulation of TLR expression in various tissues, a mechanism that may take part in the protective effect of exercise against insulin resistance. Moreover, TLRs seem to mediate the activation of mitogen-activated protein kinase p38 and Jun-amino-terminal kinase by extracellular NEFAs during endurance exercise. During this type of exercise, circulating NEFAs are known to regulate the expression of various genes including pyruvate dehydrogenase kinase 4, uncoupling protein 3, carnitine palmitoyltransferase 1, and peroxisome proliferator-activated receptor-gamma coactivator 1 alpha. Whether these events are initiated by a TLR-dependent signal transduction remains to be investigated.
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Affiliation(s)
- Marc Francaux
- Research Group in Muscle and Exercise Physiology, Institute of Neuroscience, Université catholique de Louvain, Place Pierre de Coubertin – 1, 1348 Louvain-la-Neuve, Belgium (e-mail: )
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Ochiai M, Matsuo T. Prolonged Swimming Exercise Does Not Affect Contents and Fatty Acids Composition of Rat Muscle Triacylglycerol. J Oleo Sci 2009; 58:313-21. [DOI: 10.5650/jos.58.313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Silveira LR, Fiamoncini J, Hirabara SM, Procópio J, Cambiaghi TD, Pinheiro CHJ, Lopes LR, Curi R. Updating the effects of fatty acids on skeletal muscle. J Cell Physiol 2008; 217:1-12. [PMID: 18543263 DOI: 10.1002/jcp.21514] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this review we updated the fatty acid (FA) effects on skeletal muscle metabolism. Abnormal FA availability induces insulin resistance and accounts for several of its symptoms and complications. Efforts to understand the pathogenesis of insulin resistance are focused on disordered lipid metabolism and consequently its effect on insulin signaling pathway. We reviewed herein the FA effects on metabolism, signaling, regulation of gene expression and oxidative stress in insulin resistance. The elevated IMTG content has been associated with increased intracellular content of diacylglycerol (DAG), ceramides and long-chain acyl-coenzyme A (LCA-CoA). This condition has been shown to promote insulin resistance by interfering with phosphorylation of proteins of the insulin pathway including insulin receptor substrate-1/2 (IRS), phosphatidylinositol-3-kinase, (PI3-kinase) and protein kinase C. Although the molecular mechanism is not completely understood, elevated reactive oxygen (ROS) and nitrogen species (RNS) are involved in this process. Elevated ROS/RNS activates nuclear factor-kappaB (NFkB), which promotes the transcription of proinflammatory tumoral necrosis factor alpha (TNFalpha), decreasing the insulin response. Therefore, oxidative stress induced by elevated FA availability may constitute one of the major causes of insulin resistance in skeletal muscle.
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Affiliation(s)
- Leonardo R Silveira
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
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Schummer CM, Werner U, Tennagels N, Schmoll D, Haschke G, Juretschke HP, Patel MS, Gerl M, Kramer W, Herling AW. Dysregulated pyruvate dehydrogenase complex in Zucker diabetic fatty rats. Am J Physiol Endocrinol Metab 2008; 294:E88-96. [PMID: 17957038 DOI: 10.1152/ajpendo.00178.2007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mitochondrial pyruvate dehydrogenase complex (PDC) is inactivated in many tissues during starvation and diabetes. We investigated carbohydrate oxidation (CHO) and the regulation of the PDC in lean and obese Zucker diabetic fatty (ZDF) rats during fed and starved conditions as well as during an oral glucose load without and with pharmacologically reduced levels of free fatty acids (FFA) to estimate the relative contribution of FFA on glucose tolerance, CHO, and PDC activity. The increase in total PDC activity (20-45%) was paralleled by increased protein levels ( approximately 2-fold) of PDC subunits in liver and muscle of obese ZDF rats. Pyruvate dehydrogenase kinase-4 (PDK4) protein levels were higher in obese rats, and consequently PDC activity was reduced. Although PDK4 protein levels were rapidly downregulated (57-62%) in both lean and obese animals within 2 h after glucose challenge, CHO over 3 h as well as the peak of PDC activity (1 h after glucose load) in liver and muscle were significantly lower in obese rats compared with lean rats. Similar differences were obtained with pharmacologically suppressed FFA by nicotinic acid, but with significantly improved glucose tolerance in obese rats, as well as increased CHO and delta increases in PDC activity (0-60 min) both in muscle and liver. These results demonstrated the suppressive role of FFA acids on the measured parameters. Furthermore, the results clearly demonstrate a rapid reactivation of PDC in liver and muscle of lean and obese rats after a glucose load and show that PDC activity is significantly lower in obese ZDF rats.
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Affiliation(s)
- Christoph M Schummer
- Sanofi-Aventis Deutschland GmbH, Industriepark Hoechst, 65926 Frankfurt am Main, Germany
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Abstract
PURPOSE OF REVIEW This review highlights some recent findings regarding nutritional and endocrine regulators of mitochondrial mass and function and their association with insulin resistance. RECENT FINDINGS Insulin resistance is central to many chronic metabolic diseases, including obesity, type 2 diabetes, dyslipidemia, and hypertension. Insulin resistance in skeletal muscle is associated with lower mitochondrial mass and reduced oxidative phosphorylation. Part of the mitochondrial dysfunction can be triggered by adverse nutrition. Increased fatty acid exposure, resulting from high fats diets or overfeeding, is linked to both decreased mitochondrial number and markers of oxidative phosphorylation. Caloric restriction and the adiponectin signaling pathway, however, can stimulate mitochondrial biogenesis by elevating the transcriptional machinery that regulates mitochondrial mass, improving mitochondrial efficiency, activating the peroxisome proliferator-activated receptor coactivator 1alpha mediated reactive oxygen species scavenging mechanism, and lowering reactive oxygen species production. SUMMARY States of insulin resistance are characterized by defects in lipid and carbohydrate metabolism. Abnormalities in oxidative capacity, however, can be partially normalized by caloric restriction by modulating mitochondrial mass in an insulin sensitizing manner.
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Bradley NS, Heigenhauser GJF, Roy BD, Staples EM, Inglis JG, LeBlanc PJ, Peters SJ. The acute effects of differential dietary fatty acids on human skeletal muscle pyruvate dehydrogenase activity. J Appl Physiol (1985) 2007; 104:1-9. [PMID: 17947500 DOI: 10.1152/japplphysiol.00636.2007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pyruvate dehydrogenase (PDH) is an important regulator of carbohydrate oxidation during exercise, and its activity can be downregulated by an increase in dietary fat. The purpose of this study was to determine the acute metabolic effects of differential dietary fatty acids on the activation of the PDH complex (PDHa activity) at rest and at the onset of moderate-intensity exercise. University-aged male subjects (n = 7) underwent two fat-loading trials spaced at least 2 wk apart. Subjects consumed approximately 300 g saturated (SFA) or n-6 polyunsaturated fatty acid (PUFA) fat over the course of 5 h. Following this, participants cycled at 65% of their maximum oxygen uptake for 15 min. Muscle biopsies were taken before and following fat loading and at 1 min exercise. Plasma free fatty acids increased from 0.15 +/- 0.07 to 0.54 +/- 0.19 mM over 5 h with SFA and from 0.11 +/- 0.04 to 0.35 +/- 0.13 mM with n-6 PUFA and were significantly lower throughout the n-6 PUFA trial. PDHa activity was unchanged following fat loading but increased at the onset of exercise in the SFA trial, from 1.18 +/- 0.27 to 2.16 +/- 0.37 mmol x min(-1) x kg wet wt(-1). This effect was negated in the n-6 PUFA trial (1.04 +/- 0.20 to 1.28 +/- 0.36 mmol x min(-1) x kg wet wt(-1)). PDH kinase was unchanged in both trials, suggesting that the attenuation of PDHa activity with n-6 PUFA was a result of changes in the concentrations of intramitochondrial effectors, potentially intramitochondrial NADH or Ca(2+). Our findings suggest that attenuated PDHa activity contributes to the preferential oxidation of n-6 PUFA during moderate-intensity exercise.
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Affiliation(s)
- Nicolette S Bradley
- Faculty of Applied Health Sciences, Brock Univ., St. Catharines, Ontario, Canada
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Birkenfeld AL, Boschmann M, Jordan J. Metabolic regulation: effects of natriuretic peptide interactions. Expert Rev Endocrinol Metab 2007; 2:607-614. [PMID: 30736123 DOI: 10.1586/17446651.2.5.607] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In addition to their well-established effects on blood pressure and volume homeostasis, natriuretic peptides have complex effects on carbohydrate and lipid metabolism. In vivo, pharmacological and physiological concentrations of atrial natriuretic peptides induce lipolysis in a concentration-dependent manner and increase the lipid oxidation rate. The response appears to be mediated through the stimulation of natriuretic peptide receptor-A. More recent studies suggest that natriuretic peptides also affect the production of several adipokines. These mechanisms may be relevant, as natriuretic peptide availability is altered in numerous physiological and pathological conditions, including physical exercise, congestive heart failure and obesity.
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Affiliation(s)
- Andreas L Birkenfeld
- a Franz-Volhard Clinical Research Center, Haus 129, Charité Campus Buch, Wiltbergstr. 50, 13125 Berlin, Germany
| | - Michael Boschmann
- a Franz-Volhard Clinical Research Center, Haus 129, Charité Campus Buch, Wiltbergstr. 50, 13125 Berlin, Germany
| | - Jens Jordan
- b Franz-Volhard Clinical Research Center, Haus 129, Charité Campus Buch, Wiltbergstr. 50, 13125 Berlin, Germany.
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Churchley EG, Coffey VG, Pedersen DJ, Shield A, Carey KA, Cameron-Smith D, Hawley JA. Influence of preexercise muscle glycogen content on transcriptional activity of metabolic and myogenic genes in well-trained humans. J Appl Physiol (1985) 2007; 102:1604-11. [PMID: 17218424 DOI: 10.1152/japplphysiol.01260.2006] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
To determine whether preexercise muscle glycogen content influences the transcription of several early-response genes involved in the regulation of muscle growth, seven male strength-trained subjects performed one-legged cycling exercise to exhaustion to lower muscle glycogen levels (Low) in one leg compared with the leg with normal muscle glycogen (Norm) and then the following day completed a unilateral bout of resistance training (RT). Muscle biopsies from both legs were taken at rest, immediately after RT, and after 3 h of recovery. Resting glycogen content was higher in the control leg (Norm leg) than in the Low leg (435 +/- 87 vs. 193 +/- 29 mmol/kg dry wt; P < 0.01). RT decreased glycogen content in both legs (P < 0.05), but postexercise values remained significantly higher in the Norm than the Low leg (312 +/- 129 vs. 102 +/- 34 mmol/kg dry wt; P < 0.01). GLUT4 (3-fold; P < 0.01) and glycogenin mRNA abundance (2.5-fold; not significant) were elevated at rest in the Norm leg, but such differences were abolished after exercise. Preexercise mRNA abundance of atrogenes was also higher in the Norm compared with the Low leg [atrogin: approximately 14-fold, P < 0.01; RING (really interesting novel gene) finger: approximately 3-fold, P < 0.05] but decreased for atrogin in Norm following RT (P < 0.05). There were no differences in the mRNA abundance of myogenic regulatory factors and IGF-I in the Norm compared with the Low leg. Our results demonstrate that 1) low muscle glycogen content has variable effects on the basal transcription of select metabolic and myogenic genes at rest, and 2) any differences in basal transcription are completely abolished after a single bout of heavy resistance training. We conclude that commencing resistance exercise with low muscle glycogen does not enhance the activity of genes implicated in promoting hypertrophy.
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Abstract
Mammalian hibernation is characterized by profound reductions in metabolism, oxygen consumption and heart rate. As a result, the animal enters a state of suspended animation where core body temperatures can plummet as low as -2.9 degrees C. Not only can hibernating mammals survive these physiological extremes, but they also return to a normothermic state of activity without reperfusion injury or other ill effects. This review examines recent findings on the genes, proteins and small molecules that control the induction and maintenance of hibernation in mammals. The molecular events involved with remodeling metabolism, inducing hypothermia and maintaining organ function are discussed and considered with respect to analogous processes in non-hibernating mammals such as mice and humans. The advent of sequenced genomes from three distantly related hibernators, a bat, hedgehog and ground squirrel, provides additional opportunities for molecular biologists to explore the mechanistic aspects of this biological adaptation in greater detail.
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Affiliation(s)
- Matthew T Andrews
- Department of Biology, University of Minnesota Duluth, 1035 Kirby Drive, Duluth, MN 55812, USA.
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Tunstall RJ, McAinch AJ, Hargreaves M, van Loon LJC, Cameron-Smith D. Reduced plasma free fatty acid availability during exercise: effect on gene expression. Eur J Appl Physiol 2006; 99:485-93. [PMID: 17186295 DOI: 10.1007/s00421-006-0376-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2006] [Indexed: 11/30/2022]
Abstract
Endurance exercise transiently increases the mRNA of key regulatory proteins involved in skeletal muscle metabolism. During prolonged exercise and subsequent recovery, circulating plasma fatty acid (FA) concentrations are elevated. The present study therefore aimed to determine the sensitivity of key metabolic genes to FA exposure, assessed in vitro using L6 myocytes and secondly, to measure the expression of these same set of genes in vivo, following a single exercise bout when the post-exercise rise in plasma FA is abolished by acipimox. Initial studies using L6 myotubes demonstrated dose responsive sensitivity for both PDK4 and PGC-1alpha mRNA to acute FA exposure in vitro. Nine active males performed two trials consisting of 2 h exercise, followed by 2 h of recovery. In one trial, plasma FA availability was reduced by the administration of acipimox (LFA), a pharmacological inhibitor of adipose tissue lipolysis, and in the second trial a placebo was provided (CON). During the exercise bout and during recovery, the rise in plasma FA and glycerol was abolished by acipimox treatment. Following exercise the mRNA abundance of PDK4 and PGC-1alpha were elevated and unaffected by either acipimox or placebo. Further analysis of skeletal muscle gene expression demonstrated that the CPT I gene was suppressed in both trials, whilst UCP-3 gene was only modestly regulated by exercise alone. Acipimox ingestion did not alter the response for both CPT I and UCP-3. Thus, this study demonstrates that the normal increase in circulating concentrations of FA during the later stages of exercise and subsequent recovery is not required to induce skeletal muscle mRNA expression of several proteins involved in regulating substrate metabolism.
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Affiliation(s)
- Rebecca J Tunstall
- School of Exercise and Nutritional Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
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19
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Birkenfeld AL, Boschmann M, Moro C, Adams F, Heusser K, Tank J, Diedrich A, Schroeder C, Franke G, Berlan M, Luft FC, Lafontan M, Jordan J. Beta-adrenergic and atrial natriuretic peptide interactions on human cardiovascular and metabolic regulation. J Clin Endocrinol Metab 2006; 91:5069-75. [PMID: 16984990 PMCID: PMC2072963 DOI: 10.1210/jc.2006-1084] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Atrial natriuretic peptide (ANP) has well-known cardiovascular effects and modifies lipid and carbohydrate metabolism in humans. OBJECTIVE The objective of the study was to determine the metabolic and cardiovascular interaction of beta-adrenergic receptors and ANP. DESIGN This was a crossover study, conducted 2004-2005. SETTING The study was conducted at an academic clinical research center. PATIENTS PATIENTS included 10 healthy young male subjects (body mass index 24 +/- 1 kg/m2). INTERVENTION We infused iv incremental ANP doses (6.25, 12.5, and 25 ng/kg.min) with and without propranolol (0.20 mg/kg in divided doses followed by 0.033 mg/kg.h infusion). Metabolism was monitored through venous blood sampling, im, and sc microdialysis and indirect calorimetry. Cardiovascular changes were monitored by continuous electrocardiogram and beat-by-beat blood pressure recordings. MAIN OUTCOME MEASURES Venous nonesterified fatty acid, glycerol, glucose, and insulin; and microdialysate glucose, glycerol, lactate, and pyruvate were measured. RESULTS ANP increased heart rate dose dependently. beta-Adrenergic receptor blockade abolished the response. ANP elicited a dose-dependent increase in serum nonesterified fatty acid and glycerol concentrations. The response was not suppressed with propranolol. Venous glucose and insulin concentrations increased with ANP, both without or with propranolol. ANP induced lipid mobilization in sc adipose tissue. In skeletal muscle, microdialysate lactate increased, whereas the lactate to pyruvate ratio decreased, both with and without propranolol. Higher ANP doses increased lipid oxidation, whereas energy expenditure remained unchanged. Propranolol tended to attenuate the increase in lipid oxidation. CONCLUSIONS Selected cardiovascular ANP effects are at least partly mediated by beta-adrenergic receptor stimulation. ANP-induced changes in lipid mobilization and glycolysis are mediated by another mechanism, presumably stimulation of natriuretic peptide receptors, whereas substrate oxidation might be modulated through adrenergic mechanisms.
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Affiliation(s)
- Andreas L. Birkenfeld
- Franz-Volhard Clinical Research Center
CharitéCampus Buch and HELIOS Klinikum
Berlin,DE
| | - Michael Boschmann
- Franz-Volhard Clinical Research Center
CharitéCampus Buch and HELIOS Klinikum
Berlin,DE
| | - Cedric Moro
- Unité de recherche sur les obésités
INSERM : U586 IFR31Université Paul Sabatier - Toulouse IIIInstitut Louis Bugnard
Hôpital de Rangueil
1, Avenue Jean Poulhès
31432 TOULOUSE CEDEX 4,FR
| | - Frauke Adams
- Franz-Volhard Clinical Research Center
CharitéCampus Buch and HELIOS Klinikum
Berlin,DE
| | - Karsten Heusser
- Franz-Volhard Clinical Research Center
CharitéCampus Buch and HELIOS Klinikum
Berlin,DE
| | - Jens Tank
- Franz-Volhard Clinical Research Center
CharitéCampus Buch and HELIOS Klinikum
Berlin,DE
| | - André Diedrich
- Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine
Vanderbilt University Medical SchoolNashville, Tennesse,US
| | - Christoph Schroeder
- Franz-Volhard Clinical Research Center
CharitéCampus Buch and HELIOS Klinikum
Berlin,DE
| | - Gabi Franke
- Franz-Volhard Clinical Research Center
CharitéCampus Buch and HELIOS Klinikum
Berlin,DE
| | - Michel Berlan
- Unité de recherche sur les obésités
INSERM : U586 IFR31Université Paul Sabatier - Toulouse IIIInstitut Louis Bugnard
Hôpital de Rangueil
1, Avenue Jean Poulhès
31432 TOULOUSE CEDEX 4,FR
| | - Friedrich C. Luft
- Franz-Volhard Clinical Research Center
CharitéCampus Buch and HELIOS Klinikum
Berlin,DE
| | - Max Lafontan
- Unité de recherche sur les obésités
INSERM : U586 IFR31Université Paul Sabatier - Toulouse IIIInstitut Louis Bugnard
Hôpital de Rangueil
1, Avenue Jean Poulhès
31432 TOULOUSE CEDEX 4,FR
| | - Jens Jordan
- Franz-Volhard Clinical Research Center
CharitéCampus Buch and HELIOS Klinikum
Berlin,DE
- * Correspondence should be adressed to: Jens Jordan
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20
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Pilegaard H, Birk JB, Sacchetti M, Mourtzakis M, Hardie DG, Stewart G, Neufer PD, Saltin B, van Hall G, Wojtaszewski JFP. PDH-E1alpha dephosphorylation and activation in human skeletal muscle during exercise: effect of intralipid infusion. Diabetes 2006; 55:3020-7. [PMID: 17065338 DOI: 10.2337/db06-0152] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To investigate pyruvate dehydrogenase (PDH)-E1alpha subunit phosphorylation and whether free fatty acids (FFAs) regulate PDH activity, seven subjects completed two trials: saline (control) and intralipid/heparin (intralipid). Each infusion trial consisted of a 4-h rest followed by a 3-h two-legged knee extensor exercise at moderate intensity. During the 4-h resting period, activity of PDH in the active form (PDHa) did not change in either trial, yet phosphorylation of PDH-E1alpha site 1 (PDH-P1) and site 2 (PDH-P2) was elevated in the intralipid compared with the control trial. PDHa activity increased during exercise similarly in the two trials. After 3 h of exercise, PDHa activity remained elevated in the intralipid trial but returned to resting levels in the control trial. Accordingly, in both trials PDH-P1 and PDH-P2 decreased during exercise, and the decrease was more marked during intralipid infusion. Phosphorylation had returned to resting levels at 3 h of exercise only in the control trial. Thus, an inverse association between PDH-E1alpha phosphorylation and PDHa activity exists. Short-term elevation in plasma FFA at rest increases PDH-E1alpha phosphorylation, but exercise overrules this effect of FFA on PDH-E1alpha phosphorylation leading to even greater dephosphorylation during exercise with intralipid infusion than with saline.
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MESH Headings
- Adult
- DNA, Complementary/genetics
- Enzyme Activation
- Exercise/physiology
- Fat Emulsions, Intravenous/administration & dosage
- Fat Emulsions, Intravenous/pharmacology
- Fatty Acids, Nonesterified/blood
- Glycogen/metabolism
- Humans
- Infusions, Intravenous
- Knee Joint
- Mitochondria, Muscle/drug effects
- Mitochondria, Muscle/enzymology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/physiology
- Phosphorylation
- Pyruvate Dehydrogenase (Lipoamide)/genetics
- Pyruvate Dehydrogenase (Lipoamide)/metabolism
- RNA/genetics
- RNA/isolation & purification
- Rest
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21
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Hawley JA, Tipton KD, Millard-Stafford ML. Promoting training adaptations through nutritional interventions. J Sports Sci 2006; 24:709-21. [PMID: 16766500 DOI: 10.1080/02640410500482727] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Training and nutrition are highly interrelated in that optimal adaptation to the demands of repeated training sessions typically requires a diet that can sustain muscle energy reserves. As nutrient stores (i.e. muscle and liver glycogen) play a predominant role in the performance of prolonged, intense, intermittent exercise typical of the patterns of soccer match-play, and in the replenishment of energy reserves for subsequent training sessions, the extent to which acutely altering substrate availability might modify the training impulse has been a key research area among exercise physiologists and sport nutritionists for several decades. Although the major perturbations to cellular homeostasis and muscle substrate stores occur during exercise, the activation of several major signalling pathways important for chronic training adaptations take place during the first few hours of recovery, returning to baseline values within 24 h after exercise. This has led to the paradigm that many chronic training adaptations are generated by the cumulative effects of the transient events that occur during recovery from each (acute) exercise bout. Evidence is accumulating that nutrient supplementation can serve as a potent modulator of many of the acute responses to both endurance and resistance training. In this article, we review the molecular and cellular events that occur in skeletal muscle during exercise and subsequent recovery, and the potential for nutrient supplementation (e.g. carbohydrate, fat, protein) to affect many of the adaptive responses to training.
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Affiliation(s)
- John A Hawley
- School of Medical Sciences, RMIT University, Bundoora, VIC, Australia.
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22
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Chabowski A, Górski J, Bonen A. Regulation of fatty acid transport: from transcriptional to posttranscriptional effects. Naunyn Schmiedebergs Arch Pharmacol 2006; 373:259-63. [PMID: 16724206 DOI: 10.1007/s00210-006-0075-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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23
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Hirabara SM, Silveira LR, Alberici LC, Leandro CVG, Lambertucci RH, Polimeno GC, Cury Boaventura MF, Procopio J, Vercesi AE, Curi R. Acute effect of fatty acids on metabolism and mitochondrial coupling in skeletal muscle. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1757:57-66. [PMID: 16375848 DOI: 10.1016/j.bbabio.2005.11.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Revised: 10/30/2005] [Accepted: 11/15/2005] [Indexed: 01/11/2023]
Abstract
Acute effects of free fatty acids (FFA) were investigated on: (1) glucose oxidation, and UCP-2 and -3 mRNA and protein levels in 1 h incubated rat soleus and extensor digitorium longus (EDL) muscles, (2) mitochondrial membrane potential in cultured skeletal muscle cells, (3) respiratory activity and transmembrane electrical potential in mitochondria isolated from rat skeletal muscle, and (4) oxygen consumption by anesthetized rats. Long-chain FFA increased both basal and insulin-stimulated glucose oxidation in incubated rat soleus and EDL muscles and reduced mitochondrial membrane potential in C2C12 myotubes and rat skeletal muscle cells. Caprylic, palmitic, oleic, and linoleic acid increased O(2) consumption and decreased electrical membrane potential in isolated mitochondria from rat skeletal muscles. FFA did not alter UCP-2 and -3 mRNA and protein levels in rat soleus and EDL muscles. Palmitic acid increased oxygen consumption by anesthetized rats. These results suggest that long-chain FFA acutely lead to mitochondrial uncoupling in skeletal muscle.
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MESH Headings
- Animals
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cells, Cultured
- Coenzyme A/metabolism
- Fatty Acids/pharmacology
- Glucose/metabolism
- In Vitro Techniques
- Insulin/pharmacology
- Ion Channels
- Linoleic Acid/pharmacology
- Membrane Potentials/drug effects
- Membrane Transport Proteins/genetics
- Membrane Transport Proteins/metabolism
- Mitochondria, Muscle/drug effects
- Mitochondria, Muscle/metabolism
- Mitochondrial Membranes/drug effects
- Mitochondrial Proteins/genetics
- Mitochondrial Proteins/metabolism
- Muscle Cells/drug effects
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/cytology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Oleic Acid/pharmacology
- Oxygen Consumption/drug effects
- Palmitic Acid/pharmacology
- RNA, Messenger/analysis
- RNA, Messenger/metabolism
- Rats
- Uncoupling Protein 2
- Uncoupling Protein 3
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Affiliation(s)
- Sandro M Hirabara
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Cidade Universitária, Av. Professor Lineu Prestes, 1524 Butantã, São Paulo, SP 05508-900, Brazil
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