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Khozoei S, Mahdavi AH, Rabiee F, Ghaedi K. Synergistic effects of punicic acid and alpha lipoic acid ameliorate inflammatory and metabolic genes expression in C2C12 myoblast cells under oxidative stress condition. Cell Biochem Funct 2023; 41:1403-1411. [PMID: 37987234 DOI: 10.1002/cbf.3875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 10/07/2023] [Accepted: 10/12/2023] [Indexed: 11/22/2023]
Abstract
Inflammation is a reaction of the immune system to infection and injury; in fact, it positioned at the center of metabolic disorders, particularly obesity, type 2 diabetes, and cardiovascular diseases. Thus play a major role not only in their development, but also exerts as a crucial linking factor among those diseases. In this regard, one of the strategies for tackling this problem is application of antioxidants to treat such diseases. The present study was performed to evaluate the synergistic effects of punicic acid (PUA) and alpha-lipoic acid (ALA) as antioxidants and radical scavenging reagents on the expression of some inflammatory and metabolism-related genes under oxidative stress in the muscle cells. The experimental treatments consisted of a range of 20, 40, 80, 160, and 320 µM of PUA, and 5, 25, 50, 100, and 200 µM of ALA with a 200 µM concentration of H2 O2 as an oxidative stress inducer. Accordingly, fatty acid treatments were applied for 24 h, and H2 O2 was treated for 1 h. Our results indicated that the simultaneous treatment of PUA and ALA at optimal concentrations (80 and 50 µM, respectively) decreased the expression of inflammation genes and increased the expression of regulatory genes (Pparγ, Pgc-1α) related to metabolism (p < .05). Unexpectedly, H2 O2 treatment increased the Fndc5 expression (p < .05). Maximal upregulation of Pparγ, Pgc-1α were obtained when fatty acids combination (PUA and ALA) were used in the culture of H2 O2 treated cells (p < .05). Therefore, our findings suggest that the simultaneous use of PUA and ALA fatty acids could reduce oxidative stress, and the expression of inflammatory genes, thereby improving the cell metabolism.
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Affiliation(s)
- Shiva Khozoei
- Department of Animal Science, College of Agriculture, Isfahan University of Technology (IUT), Isfahan, Iran
| | - Amir Hossein Mahdavi
- Department of Animal Science, College of Agriculture, Isfahan University of Technology (IUT), Isfahan, Iran
| | - Farzaneh Rabiee
- Department of Animal Biotechnology, Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Kamran Ghaedi
- Department of Animal Biotechnology, Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
- Department of Cell and Molecular Biology and Microbiology, Faculty of Biological Science and Technology, University of Isfahan (UI), Isfahan, Iran
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Son W, Brown K, Persinger A, Pryke A, Lin J, Powell Z, Wallace N, van der Merwe M, Puppa M. Effect of Omega-3 Rich High-Fat Diet on Markers of Tissue Lipid Metabolism in Glucocorticoid-Treated Mice. Int J Mol Sci 2023; 24:11492. [PMID: 37511252 PMCID: PMC10380392 DOI: 10.3390/ijms241411492] [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: 05/23/2023] [Revised: 07/07/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023] Open
Abstract
Glucocorticoids (GCs) are some of the most widely prescribed therapies for treating numerous inflammatory diseases and multiple cancer types. With chronic use, GCs' therapeutic benefits are concurrent with deleterious metabolic side effects, which worsen when combined with a high-fat diet (HFD). One characteristic of the common Western HFD is the presence of high omega-6 polyunsaturated fatty acids (PUFAs) and a deficiency in omega-3 PUFAs. The aim of this experiment was to determine whether fat composition resulting from HFD affects glucocorticoid-induced alterations in lipid-handling by the liver and skeletal muscle. Male wild-type C57BL/6 mice were randomized into two groups: n-6 (45% fat 177.5 g lard) and n-3 (45% fat 177.5 g Menhaden oil). After 4 weeks on their diets, groups were divided to receive either daily injections of dexamethasone (3 mg/kg/day) or sterile PBS for 1 week while continuing diets. The n-3 HFD diet attenuated adipose and hepatic fatty accumulation and prevented GC-induced increases in liver lipid metabolism markers Cd36 and Fabp. N-3 HFD had little effect on markers of lipid metabolism in oxidative and glycolytic skeletal muscle and was unable to attenuate GC-induced gene expression in the muscle. The present study's result demonstrated that the change of fat composition in HFD could beneficially alter the fatty acid accumulation and associated lipid metabolism markers in mice treated with dexamethasone.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Melissa Puppa
- College of Health Sciences, University of Memphis, Memphis, TN 38152, USA
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Manfredi JM, Jacob SI, Boger BL, Norton EM. A one-health approach to identifying and mitigating the impact of endocrine disorders on human and equine athletes. Am J Vet Res 2022; 84:ajvr.22.11.0194. [PMID: 36563063 DOI: 10.2460/ajvr.22.11.0194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Endocrinopathies affect multiple species in ever-increasing percentages of their populations, creating an opportunity to apply one-health approaches to determining creative preventative measures and therapies in athletes. Obesity and alterations in insulin and glucose dynamics are medical concerns that play a role in whole-body health and homeostasis in both horses and humans. The role and impact of endocrine disorders on the musculoskeletal, cardiovascular, and reproductive systems are of particular interest to the athlete. Elucidation of both physiologic and pathophysiologic mechanisms involved in disease processes, starting in utero, is important for development of prevention and treatment strategies for the health and well-being of all species. This review focuses on the unrecognized effects of endocrine disorders associated with the origins of metabolic disease; inflammation at the intersection of endocrine disease and related diseases in the musculoskeletal, cardiovascular, and reproductive systems; novel interventions; and diagnostics that are informed via multiomic and one-health approaches. Readers interested in further details on specific equine performance conditions associated with endocrine disease are invited to read the companion Currents in One Health by Manfredi et al, JAVMA, February 2023.
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Affiliation(s)
- Jane M Manfredi
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI
| | - Sarah I Jacob
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI
| | - Brooke L Boger
- Comparative Medicine and Integrative Biology, Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI
| | - Elaine M Norton
- Department of Animal and Comparative Biomedical Sciences, College of Agriculture and Life Sciences, The University of Arizona, Tucson, AZ
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Brennan NA, Fishbein KW, Reiter DA, Ferrucci L, Spencer RG. Contribution of Intramyocellular Lipids to Decreased Computed Tomography Muscle Density With Age. Front Physiol 2021; 12:632642. [PMID: 34276390 PMCID: PMC8279780 DOI: 10.3389/fphys.2021.632642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 04/21/2021] [Indexed: 12/03/2022] Open
Abstract
Skeletal muscle density, as determined by computed tomography (CT), has been shown to decline with age, resulting in increased frailty and morbidity. However, the mechanism underlying this decrease in muscle density remains elusive. We sought to investigate the role of intramyocellular lipid (IMCL) accumulation in the age-related decline in muscle density. Muscle density was measured using computerized tomography (CT), and IMCL content was quantified using in vivo proton magnetic resonance spectroscopy (1H-MRS). The study population consisted of 314 healthy participants (142 men, 32–98 years) of the Baltimore Longitudinal Study of Aging (BLSA). In addition to IMCL quantification, obesity-related covariates were measured, including body mass index (BMI), waist circumference, and circulating triglyceride concentration. Higher IMCL concentrations were significantly correlated with lower muscle density in older individuals, independent of age, sex, race, and the obesity-associated covariates (p < 0.01). Lower muscle density was also significantly associated with greater age-adjusted IMCL, a variable we constructed using LOESS regression (p < 0.05). Our results suggest that the accumulation of IMCL may be associated with a decrease in muscle density. This may serve to define a potential therapeutic target for treatment of age-associated decreased muscle function.
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Affiliation(s)
- Nicholas A Brennan
- Laboratory of Clinical Investigation, NIA, NIH, Baltimore, MD, United States
| | - Kenneth W Fishbein
- Laboratory of Clinical Investigation, NIA, NIH, Baltimore, MD, United States
| | - David A Reiter
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, United States
| | - Luigi Ferrucci
- Longitudinal Studies Section, NIA, NIH, Baltimore, MD, United States
| | - Richard G Spencer
- Laboratory of Clinical Investigation, NIA, NIH, Baltimore, MD, United States
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Tadano K, Okamoto Y, Isobe T, Mori S, Suzuki H, Minami M, Sakae T. Changes in skeletal muscle diffusion parameters owing to intramyocellular lipid. Magn Reson Imaging 2020; 73:70-75. [PMID: 32853758 DOI: 10.1016/j.mri.2020.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 07/09/2020] [Accepted: 08/14/2020] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Several studies investigated the changes in diffusion of water molecules in skeletal muscle cells of lifestyle-related-disease patients who performed a hybrid training (HYBT) for six months. They reported that the apparent diffusion coefficient (ADC) and all diffusion eigenvalues (λ1, λ2, and λ3) increased after the HYBT, owing to the enlargement of the intramyocellular diffusion space (intracellular space) caused by the muscular hypertrophy. We assumed that the HYBT promoted metabolism of the whole skeletal muscle including lipids, which reduced the amount of intramyocellular lipid (IMCL), and led to a secondary enlargement of the diffusion space in the skeletal muscle cells. However, the IMCL has to be a diffusion limiting factor in order to verify this hypothesis. Until now, there is no report on whether IMCL is a diffusion limiting factor for water molecules. The objective of this study was to examine whether the IMCL is a diffusion limiting factor in skeletal muscle cells. MATERIALS AND METHODS We performed a three-dimensional quantification of the IMCL in triceps surae muscles of lifestyle-related-disease patients and healthy volunteers. In addition, we measured the ADC in the volume of interest (VOI), diffusion anisotropy (FA), and diffusion eigenvalues (λ1, λ2, and λ3), and evaluated the correlations between these diffusion parameters and IMCL. RESULTS The results showed that the amount of IMCL was positively and negatively correlated with the FA and λ3, respectively, in lifestyle-related-disease patients. In addition, there was a weak negative correlation between IMCL and ADC, λ1, and λ2. There was no correlation between the amount of IMCL and diffusion parameters of healthy volunteers. DISCUSSION Above a certain amount, the IMCL correlates with the diffusion parameters. A higher amount of IMCL leads to smaller diffusion eigenvalues. This result suggested that IMCL possibility of influencing diffusion of water molecules in skeletal muscle cells. However, in order for the influence of IMCL to be reflected in the diffusion eigenvalues, it was needed large amount of IMCL existed, and we thought that the influence was smaller than the influence by the already reported cell membrane.
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Affiliation(s)
- Kiichi Tadano
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan; Faculty of Health Sciences, Kyorin University, 5-4-1 Shimorenjaku, Mitaka, Tokyo 181-8612, Japan.
| | - Yoshikazu Okamoto
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Tomonori Isobe
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Shintaro Mori
- Department of Early Childhood Education and Nurture, Tokiwa Junior College, 1-430-1, Miwa Mito, Ibaraki 310-8585, Japan
| | - Hiroaki Suzuki
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Manabu Minami
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Takeji Sakae
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
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Schilder RJ, Stewart H. Parasitic gut infection in Libellula pulchella causes functional and molecular resemblance of dragonfly flight muscle to skeletal muscle of obese vertebrates. ACTA ACUST UNITED AC 2019; 222:jeb.188508. [PMID: 30659084 DOI: 10.1242/jeb.188508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 01/11/2019] [Indexed: 12/31/2022]
Abstract
We previously demonstrated the existence of a naturally occurring metabolic disease phenotype in Libellula pulchella dragonflies that shows high similarity to vertebrate obesity and type II diabetes, and is caused by a protozoan gut parasite. To further mechanistic understanding of how this metabolic disease phenotype affects fitness of male L. pulchella in vivo, we examined infection effects on in situ muscle performance and molecular traits relevant to dragonfly flight performance in nature. Importantly, these traits were previously shown to be affected in obese vertebrates. Similarly to obesity effects in rat skeletal muscle, dragonfly gut infection caused a disruption of relationships between body mass, flight muscle power output and alternative pre-mRNA splicing of troponin T, which affects muscle calcium sensitivity and performance in insects and vertebrates. In addition, when simulated in situ to contract at cycle frequencies ranging from 20 to 45 Hz, flight muscles of infected individuals displayed a left shift in power-cycle frequency curves, indicating a significant reduction in their optimal cycle frequency. Interestingly, these power-cycle curves were similar to those produced by flight muscles of non-infected teneral (i.e. physiologically immature) adult L. pulchella males. Overall, our results indicate that the effects of metabolic disease on skeletal muscle physiology in natural insect systems are similar to those observed in vertebrates maintained in laboratory settings. More generally, they indicate that study of natural, host-parasite interactions can contribute important insight into how environmental factors other than diet and exercise may contribute to the development of metabolic disease phenotypes.
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Affiliation(s)
- Rudolf J Schilder
- Pennsylvania State University, Department of Entomology, 501 Ag Sciences & Industries Building, State College, PA 16802, USA .,Pennsylvania State University, Department of Biology, 501 Ag Sciences & Industries Building, State College, PA 16802, USA
| | - Hannah Stewart
- Pennsylvania State University, Department of Entomology, 501 Ag Sciences & Industries Building, State College, PA 16802, USA
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HDAC6 Suppresses Age-Dependent Ectopic Fat Accumulation by Maintaining the Proteostasis of PLIN2 in Drosophila. Dev Cell 2017; 43:99-111.e5. [DOI: 10.1016/j.devcel.2017.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 05/01/2017] [Accepted: 08/31/2017] [Indexed: 01/05/2023]
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Kim B, Lee SG, Park YK, Ku CS, Pham TX, Wegner CJ, Yang Y, Koo SI, Chun OK, Lee JY. Blueberry, blackberry, and blackcurrant differentially affect plasma lipids and pro-inflammatory markers in diet-induced obesity mice. Nutr Res Pract 2016; 10:494-500. [PMID: 27698956 PMCID: PMC5037066 DOI: 10.4162/nrp.2016.10.5.494] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 03/16/2016] [Accepted: 06/21/2016] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND/OBJECTIVES Evidence indicates that berry anthocyanins are anti-atherogenic, antioxidant, and anti-inflammatory. However, berries differ vastly in their anthocyanin composition and thus potentially in their biological and metabolic effects. The present study compared hypolipidemic, antioxidant, and anti-inflammatory properties of blueberry (BB), blackberry (BK), and blackcurrant (BC) in a diet-induced obesity (DIO) mouse model. MATERIALS/METHODS Male C57BL/6J mice were fed a high fat (HF; 35% fat, w/w) control diet or a HF diet supplemented with freeze-dried 5% BB, 6.3% BK or 5.7% BC for 12 weeks (10 mice/group) to achieve the same total anthocyanin content in each diet. Plasma lipids, antioxidant status and pro-inflammatory cytokines were measured. The expression of genes involved in antioxidant defense, inflammation, and lipid metabolism was determined in the liver, epididymal adipose tissue, proximal intestine, and skeletal muscle. Histological analysis was performed to identify crown-like structure (CLS) in epididymal fat pads to determine macrophage infiltration. RESULTS No differences were noted between the control and any berry-fed groups in plasma levels of liver enzymes, insulin, glucose, ferric reducing antioxidant power, superoxide dismutase, and tumor necrosis factor α. However, BK significantly lowered plasma triglyceride compared with the HF control and other berries, whereas BC significantly reduced F4/80 mRNA and the number of CLS in the epididymal fat pad, indicative of less macrophage infiltration. CONCLUSIONS The present study provides evidence that BB, BK and BC with varying anthocyanin composition differentially affect plasma lipids and adipose macrophage infiltration in DIO mice, but with no differences in their antioxidant capacity and anti-inflammatory potential.
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Affiliation(s)
- Bohkyung Kim
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Sang Gil Lee
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Young-Ki Park
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Chai Siah Ku
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Tho X Pham
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Casey J Wegner
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Yue Yang
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Sung I Koo
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Ock K Chun
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Ji-Young Lee
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
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Petrov PD, Ribot J, López-Mejía IC, Fajas L, Palou A, Bonet ML. Retinoblastoma Protein Knockdown Favors Oxidative Metabolism and Glucose and Fatty Acid Disposal in Muscle Cells. J Cell Physiol 2015; 231:708-18. [DOI: 10.1002/jcp.25121] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 07/31/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Petar D. Petrov
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn); Spain
| | - Joan Ribot
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn); Spain
| | | | - Lluís Fajas
- Department of Physiology; Université de Lausanne; Switzerland
| | - Andreu Palou
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn); Spain
| | - M. Luisa Bonet
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn); Spain
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Ogasawara J, Izawa T, Sakurai T, Sakurai T, Shirato K, Ishibashi Y, Ishida H, Ohno H, Kizaki T. The Molecular Mechanism Underlying Continuous Exercise Training-Induced Adaptive Changes of Lipolysis in White Adipose Cells. J Obes 2015; 2015:473430. [PMID: 26075089 PMCID: PMC4444571 DOI: 10.1155/2015/473430] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 04/04/2015] [Accepted: 04/27/2015] [Indexed: 01/04/2023] Open
Abstract
Physical exercise accelerates the mobilization of free fatty acids from white adipocytes to provide fuel for energy. This happens in several tissues and helps to regulate a whole-body state of metabolism. Under these conditions, the hydrolysis of triacylglycerol (TG) that is found in white adipocytes is known to be augmented via the activation of these lipolytic events, which is referred to as the "lipolytic cascade." Indeed, evidence has shown that the lipolytic responses in white adipocytes are upregulated by continuous exercise training (ET) through the adaptive changes in molecules that constitute the lipolytic cascade. During the past few decades, many lipolysis-related molecules have been identified. Of note, the discovery of a new lipase, known as adipose triglyceride lipase, has redefined the existing concepts of the hormone-sensitive lipase-dependent hydrolysis of TG in white adipocytes. This review outlines the alterations in the lipolytic molecules of white adipocytes that result from ET, which includes the molecular regulation of TG lipases through the lipolytic cascade.
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Affiliation(s)
- Junetsu Ogasawara
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
- *Junetsu Ogasawara:
| | - Tetsuya Izawa
- Graduate School of Health and Sports Science, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| | - Tomonobu Sakurai
- Faculty of Culture and Sport Policy, Toin University of Yokohama, Yokohama, Kanagawa 225-8503, Japan
| | - Takuya Sakurai
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Ken Shirato
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Yoshinaga Ishibashi
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Hitoshi Ishida
- Department of Third Internal Medicine, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Hideki Ohno
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Takako Kizaki
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan
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Jiao tai wan attenuates hepatic lipid accumulation in type 2 diabetes mellitus. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:567045. [PMID: 24319477 PMCID: PMC3844214 DOI: 10.1155/2013/567045] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 09/08/2013] [Indexed: 12/30/2022]
Abstract
Jiao Tai Wan (JTW), a Chinese herbal formula containing Rhizoma Coptidis and Cortex Cinnamomi, has been used for diabetic treatment for many years. The aim of this study was to determine the main components in JTW and to investigate the effects of JTW on hepatic lipid accumulation in diabetic rats and humans. JTW extract was prepared and the main components were assayed by HPLC. An animal model of diabetes mellitus was established and JTW was administered intragastrically. In the clinical study, diabetic patients with poor glycemic control were treated with JTW. Blood glucose and lipid parameters, liver histology, hepatic triglyceride content and lipogenic gene expression were examined. Our data demonstrated that JTW significantly improved hyperglycemia, hyperlipidemia and hepatic lipid accumulation in diabetic rats. This was accompanied by the down-regulation of acetyl coenzyme A carboxylase (ACC) and fatty acid synthase (FAS) protein expressions, and the up-regulation of AMP-activated protein kinase (AMPK) and phosphorylated-ACC (pACC) protein expressions in the liver tissues. Diabetic patients also exhibited decreases in their hepatic triglyceride content. The results suggest that JTW attenuates hepatic lipid accumulation in diabetic rats and humans. These beneficial effects are possibly associated with the inhibition of lipogenic gene expression in the liver.
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Mavros Y, Kay S, Anderberg KA, Baker MK, Wang Y, Zhao R, Meiklejohn J, Climstein M, O'Sullivan A, de Vos N, Baune BT, Blair SN, Simar D, Rooney K, Singh N, Fiatarone Singh MA. Changes in insulin resistance and HbA1c are related to exercise-mediated changes in body composition in older adults with type 2 diabetes: interim outcomes from the GREAT2DO trial. Diabetes Care 2013; 36:2372-9. [PMID: 23474589 PMCID: PMC3714491 DOI: 10.2337/dc12-2196] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To investigate changes in body composition after 12 months of high-intensity progressive resistance training (PRT) in relation to changes in insulin resistance (IR) or glucose homeostasis in older adults with type 2 diabetes. RESEARCH DESIGN AND METHODS One-hundred three participants were randomized to receive either PRT or sham exercise 3 days per week for 12 months. Homeostasis model assessment 2 of insulin resistance (HOMA2-IR) and glycosylated hemoglobin (HbA1c) were used as indices of IR and glucose homeostasis. Skeletal muscle mass (SkMM) and total fat mass were assessed using bioelectrical impedance. Visceral adipose tissue, mid-thigh cross-sectional area, and mid-thigh muscle attenuation were quantified using computed tomography. RESULTS Within the PRT group, changes in HOMA2-IR were associated with changes in SkMM (r = -0.38; P = 0.04) and fat mass (r = 0.42; P = 0.02). Changes in visceral adipose tissue tended to be related to changes in HOMA2-IR (r = 0.35; P = 0.07). Changes in HbA1c were related to changes in mid-thigh muscle attenuation (r = 0.52; P = 0.001). None of these relationships were present in the sham group (P > 0.05). Using ANCOVA models, participants in the PRT group who had increased SkMM had decreased HOMA2-IR (P = 0.05) and HbA1c (P = 0.09) compared with those in the PRT group who lost SkMM. Increases in SkMM in the PRT group decreased HOMA2-IR (P = 0.07) and HbA1c (P < 0.05) compared with those who had increased SkMM in the sham group. CONCLUSIONS Improvements in metabolic health in older adults with type 2 diabetes were mediated through improvements in body composition only if they were achieved through high-intensity PRT.
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Affiliation(s)
- Yorgi Mavros
- Exercise Health and Performance Faculty Research Group, Faculty of Health Sciences, University of Sydney, Sydney, Australia.
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Yokota T, Kinugawa S, Yamato M, Hirabayashi K, Suga T, Takada S, Harada K, Morita N, Oyama-Manabe N, Kikuchi Y, Okita K, Tsutsui H. Systemic oxidative stress is associated with lower aerobic capacity and impaired skeletal muscle energy metabolism in patients with metabolic syndrome. Diabetes Care 2013; 36:1341-6. [PMID: 23393211 PMCID: PMC3631820 DOI: 10.2337/dc12-1161] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Systemic oxidative stress is associated with insulin resistance and obesity. We tested the hypothesis that systemic oxidative stress is linked to lower aerobic capacity and skeletal muscle dysfunction in metabolic syndrome (MetS). RESEARCH DESIGN AND METHODS The incremental exercise testing with cycle ergometer was performed in 14 male patients with MetS and 13 age-, sex-, and activity-matched healthy subjects. Systemic lipid peroxidation was assessed by serum thiobarbituric acid reactive substances (TBARS), and systemic antioxidant defense capacity was assessed by serum total thiols and enzymatic activity of superoxide dismutase (SOD). To assess skeletal muscle energy metabolism, we measured high-energy phosphates in the calf muscle during plantar flexion exercise and intramyocellular lipid (IMCL) in the resting leg muscle, using (31)P- and (1)proton-magnetic resonance spectroscopy, respectively. RESULTS Serum TBARS were elevated (12.4 ± 7.1 vs. 3.7 ± 1.1 μmol/L; P < 0.01), and serum total thiols and SOD activity were decreased (290.8 ± 51.2 vs. 398.7 ± 105.2 μmol/L, P < 0.01; and 22.2 ± 8.4 vs. 31.5 ± 8.5 units/L, P < 0.05, respectively) in patients with MetS compared with healthy subjects. Peak VO2 and anaerobic threshold normalized to body weight were significantly lower in MetS patients by 25 and 31%, respectively, and inversely correlated with serum TBARS (r = -0.49 and r = -0.50, respectively). Moreover, muscle phosphocreatine loss during exercise was 1.4-fold greater in patients with MetS (P < 0.05), and IMCL content was 2.9-fold higher in patients with MetS (P < 0.01), indicating impaired skeletal muscle energy metabolism, and these indices positively correlated with serum TBARS (r = 0.45 and r = 0.63, respectively). CONCLUSIONS Systemic oxidative stress was associated with lower aerobic capacity and impaired skeletal muscle energy metabolism in patients with MetS.
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Affiliation(s)
- Takashi Yokota
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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Oh TS, Yun JW. DNA microarray analysis reveals differential gene expression in the soleus muscle between male and female rats exposed to a high fat diet. Mol Biol Rep 2012; 39:6569-80. [PMID: 22307788 DOI: 10.1007/s11033-012-1486-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 01/24/2012] [Indexed: 01/15/2023]
Abstract
It is well recognized that diet-induced dysfunctions in skeletal muscle are closely related with many metabolic diseases, such as obesity and diabetes. In the present study, we identified global changes in gender-dependent gene expressions in the soleus muscle of lean and obese rats fed a high fat diet (HFD), using DNA microarray analysis. Prior to microarray analysis, the body weight gains were found to be higher in male HFD rats than the female HFD rats. To better understand the detailed phenotypic differences in response to HFD feeding, we identified differential gene expression in soleus muscle between the genders. To this end, we extracted and summarized the genes that were up- or down-regulated more than 1.5-fold between the genders in the microarray data. As expected, a greater number of genes encoding myofibrillar proteins and glycolytic proteins were expressed higher in males than females when exposed to HFD, reflecting greater muscular activity and higher capacity for utilizing glucose as an energy fuel. However, a series of genes involved in oxidative metabolism and cellular defenses were more up-regulated in females than males. These results allowed us to conclude that compared to males, females have greater fat clearing capacity in skeletal muscle through the activation of genes encoding enzymes for fat oxidation. In conclusion, our microarray data provide a better understanding of the molecular events underlying gender dimorphism in soleus muscle, and will provide valuable information in improving gender awareness in the health care system.
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Affiliation(s)
- Tae Seok Oh
- Department of Biotechnology, Daegu University, Kyungsan, Kyungbuk, Republic of Korea
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15
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Kulkarni SS, Salehzadeh F, Fritz T, Zierath JR, Krook A, Osler ME. Mitochondrial regulators of fatty acid metabolism reflect metabolic dysfunction in type 2 diabetes mellitus. Metabolism 2012; 61:175-85. [PMID: 21816445 DOI: 10.1016/j.metabol.2011.06.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/17/2011] [Accepted: 06/20/2011] [Indexed: 10/25/2022]
Abstract
The delicate homeostatic balance between glucose and fatty acid metabolism in relation to whole-body energy regulation is influenced by mitochondrial function. We determined expression and regulation of mitochondrial enzymes including pyruvate dehydrogenase kinase (PDK) 4, PDK2, carnitine palmitoyltransferase 1b, and malonyl-coenzyme A decarboxylase in skeletal muscle from people with normal glucose tolerance (NGT) or type 2 diabetes mellitus (T2DM). Vastus lateralis biopsies were obtained from NGT (n = 79) or T2DM (n = 33) men and women matched for age and body mass index. A subset of participants participated in a 4-month lifestyle intervention program consisting of an unsupervised walking exercise. Muscle biopsies were analyzed for expression and DNA methylation status. Primary myotubes were derived from biopsies obtained from NGT individuals for metabolic studies. Cultured skeletal muscle was exposed to agents mimicking exercise activation for messenger RNA (mRNA) expression analysis. The mRNA expression of PDK4, PDK2, and malonyl-coenzyme A decarboxylase was increased in skeletal muscle from T2DM patients. Methylation of the PDK4 promoter was reduced in T2DM and inversely correlated with PDK4 expression. Moreover, PDK4 expression was positively correlated with body mass index, blood glucose, insulin, C peptide, and hemoglobin A(1c). A lifestyle intervention program resulted in increased PDK4 mRNA expression in NGT individuals, but not in those with T2DM. Exposure to caffeine or palmitate increased PDK4 mRNA in a cultured skeletal muscle system. Our findings reveal that skeletal muscle expression of PDK4 and related genes regulating mitochondrial function reflects alterations in substrate utilization and clinical features associated with T2DM. Furthermore, hypomethylation of the PDK4 promoter in T2DM coincided with an impaired response of PDK4 mRNA after exercise.
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MESH Headings
- Aged
- Biopsy
- Case-Control Studies
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/therapy
- Exercise Therapy
- Fatty Acids/metabolism
- Female
- Gene Expression Regulation, Enzymologic/physiology
- Humans
- Male
- Metabolic Diseases/etiology
- Metabolic Diseases/genetics
- Metabolic Diseases/metabolism
- Metabolic Diseases/therapy
- Middle Aged
- Mitochondria, Muscle/enzymology
- Mitochondria, Muscle/pathology
- Mitochondrial Proteins/genetics
- Mitochondrial Proteins/metabolism
- Mitochondrial Proteins/physiology
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Risk Reduction Behavior
- Walking/physiology
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Affiliation(s)
- Sameer S Kulkarni
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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16
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Yokota T, Kinugawa S, Okita K, Hirabayashi K, Suga T, Hattori M, Nakagawa Y, Oyama-Manabe N, Shirato H, Tsutsui H. Lower aerobic capacity was associated with abnormal intramuscular energetics in patients with metabolic syndrome. Hypertens Res 2011; 34:1029-34. [PMID: 21753774 DOI: 10.1038/hr.2011.78] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Lower aerobic capacity is a strong and independent predictor of cardiovascular morbidity and mortality in patients with metabolic syndrome (MetS). However, the mechanisms are not fully elucidated. We tested the hypothesis that skeletal muscle dysfunction could contribute to the lower aerobic capacity in MetS patients. The incremental exercise tests with cycle ergometer were performed in 12 male patients with MetS with no habitual exercise and 11 age-, sex- and activity-matched control subjects to assess the aerobic capacity. We performed (31)phosphorus-magnetic resonance spectroscopy (MRS) to assess the high-energy phosphate metabolism in skeletal muscle during aerobic exercise. Proton-MRS was also performed to measure intramyocellular lipid (IMCL) content. Peak oxygen uptake (peak VO(2); 34.1±6.2 vs. 41.4±8.4 ml kg(-1) min(-1), P<0.05) and anaerobic threshold (AT; 18.0±2.4 vs. 23.1±3.7 ml kg(-1) min(-1), P<0.01) adjusted by lean body mass were lower in MetS patients than control subjects. Phosphocreatine (PCr) loss during exercise was 1.5-fold greater in MetS, suggesting reduced intramuscular oxidative capacity. PCr loss was inversely correlated with peak VO(2) (r=-0.64) and AT (r=-0.60), respectively. IMCL content was threefold higher in MetS and was inversely correlated with peak VO(2) (r=-0.47) and AT (r=-0.52), respectively. Moreover, there was a positive correlation between IMCL content and PCr loss (r=0.64). These results suggested that lean-body aerobic capacity in MetS patients was lower compared with activity-matched healthy subjects, which might be due to the reduced intramuscular fatty acid oxidative metabolism.
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Affiliation(s)
- Takashi Yokota
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan
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17
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Tan CK, Leuenberger N, Tan MJ, Yan YW, Chen Y, Kambadur R, Wahli W, Tan NS. Smad3 deficiency in mice protects against insulin resistance and obesity induced by a high-fat diet. Diabetes 2011; 60:464-76. [PMID: 21270259 PMCID: PMC3028346 DOI: 10.2337/db10-0801] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Obesity and associated pathologies are major global health problems. Transforming growth factor-β/Smad3 signaling has been implicated in various metabolic processes, including adipogenesis, insulin expression, and pancreatic β-cell function. However, the systemic effects of Smad3 deficiency on adiposity and insulin resistance in vivo remain elusive. This study investigated the effects of Smad3 deficiency on whole-body glucose and lipid homeostasis and its contribution to the development of obesity and type 2 diabetes. RESEARCH DESIGN AND METHODS We compared various metabolic profiles of Smad3-knockout and wild-type mice. We also determined the mechanism by which Smad3 deficiency affects the expression of genes involved in adipogenesis and metabolism. Mice were then challenged with a high-fat diet to study the impact of Smad3 deficiency on the development of obesity and insulin resistance. RESULTS Smad3-knockout mice exhibited diminished adiposity with improved glucose tolerance and insulin sensitivity. Chromatin immunoprecipitation assay revealed that Smad3 deficiency increased CCAAT/enhancer-binding protein β-C/EBP homologous protein 10 interaction and exerted a differential regulation on proliferator-activated receptor β/δ and proliferator-activated receptor γ expression in adipocytes. Focused gene expression profiling revealed an altered expression of genes involved in adipogenesis, lipid accumulation, and fatty acid β-oxidation, indicative of altered adipose physiology. Despite reduced physical activity with no modification in food intake, these mutant mice were resistant to obesity and insulin resistance induced by a high-fat diet. CONCLUSIONS Smad3 is a multifaceted regulator in adipose physiology and the pathogenesis of obesity and type 2 diabetes, suggesting that Smad3 may be a potential target for the treatment of obesity and its associated disorders.
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Affiliation(s)
- Chek Kun Tan
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Nicolas Leuenberger
- Center for Integrative Genomics, National Research Center Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
| | - Ming Jie Tan
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Yew Wai Yan
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Yinghui Chen
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Ravi Kambadur
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Walter Wahli
- Center for Integrative Genomics, National Research Center Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
| | - Nguan Soon Tan
- School of Biological Sciences, Nanyang Technological University, Singapore
- Corresponding author: Nguan Soon Tan,
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18
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Kim DH, Joo JI, Choi JW, Yun JW. Differential expression of skeletal muscle proteins in high-fat diet-fed rats in response to capsaicin feeding. Proteomics 2010; 10:2870-81. [PMID: 20517883 DOI: 10.1002/pmic.200900815] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In this study, the effects of capsaicin on expression of skeletal muscle proteins in Sprague-Dawley rats fed with a high-fat diet (HFD) were investigated. Rats were fed a HFD with or without capsaicin treatment for 8 wk. After HFD feeding, capsaicin-treated rats weighed an average of 8% less than those of the HFD control group. Gastrocnemius muscle tissue from lean and obese rats with or without capsaicin treatment was arrayed using 2-DE for detection of HFD-associated markers. Proteomic analysis using 2-DE demonstrated that 36 spots from a total of approximately 600 matched spots showed significantly different expression; 27 spots were identified as gastrocnemius muscle proteins that had been altered in response to capsaicin feeding, and 6 spots could not be identified by mass fingerprinting. Expression of various muscle proteins was determined by immunoblot analysis for the determination of molecular mechanisms, whereby capsaicin caused inhibition of adipogenesis. Immunoblot analysis revealed increased uncoupling protein 3 (UCP3) protein expression in HFD-fed rats, whereas contents were reduced with capsaicin treatment. Compared with the HFD control group, capsaicin treatment increased phosphorylation of AMP-activated protein kinase (AMPIC) CP3 and acetyl-CoA carboxylase (ACC). To support this result, we also analyzed in vitro differential protein expression in L6 skeletal muscle cells. These data suggest that the AMPK-ACC-malonyl-CoA metabolic signaling pathway is one of the targets of capsaicin action. To the best of our knowledge, this is the first proteomic study to report on analysis of diet-induced alterations of protein expression that are essential for energy expenditure in rat muscle.
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Affiliation(s)
- Dong Hyun Kim
- Department of Biotechnology, Daegu University, Kynungsan, Kyungbuk, Republic of Korea
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19
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Wein S, Behm N, Petersen RK, Kristiansen K, Wolffram S. Quercetin enhances adiponectin secretion by a PPAR-gamma independent mechanism. Eur J Pharm Sci 2010; 41:16-22. [PMID: 20580672 DOI: 10.1016/j.ejps.2010.05.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 04/30/2010] [Accepted: 05/10/2010] [Indexed: 12/22/2022]
Abstract
To study possible insulin sensitizing, anti-inflammatory and anti-oxidative effects of the flavonol quercetin, rats were fed a high-fat diet (19%, w/w) with (HFQ) or without (HF) 0.03% quercetin or a flavonoid-poor low-fat (5%, w/w) maintenance diet (LF) over 4 weeks. Body weight was measured weekly, and plasma concentrations of adiponectin, leptin, insulin, glucose, triacylglycerols, total cholesterol, as well as of markers of inflammation and oxidative stress were measured (12h fasted) at the end of the feeding period. Adiponectin and peroxisome-proliferator-activated-receptor (PPAR)-gamma mRNA were measured in adipose tissue (WAT) by real-time RT-PCR. PPAR-gamma transactivation was investigated by means of a reporter gene assay. HF feeding resulted in elevated fasted plasma glucose concentrations, while HFQ did not differ from LF feeding. In the HFQ group plasma concentrations and WAT mRNA levels of adiponectin were elevated compared with the HF group, however, PPAR-gamma mRNA concentration in WAT was decreased (HFQ vs. HF). Compared to both other groups quercetin feeding significantly reduced oxidative stress, measured by plasma 8-iso-PGF(2alpha), while body weight gain, body composition and plasma leptin levels were not affected. Neither quercetin nor its metabolites induced PPAR-gamma-mediated transactivation in vitro. Adiponectin stimulating effects of quercetin are PPAR-gamma-independent and prevent impairment of insulin sensitivity without affecting body weight and composition.
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Affiliation(s)
- Silvia Wein
- Institute of Animal Nutrition & Physiology, Christian-Albrechts-University of Kiel, Herrmann-Rodewald-Str 9, D-24118 Kiel, Germany.
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20
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Nielsen J, Mogensen M, Vind BF, Sahlin K, Højlund K, Schrøder HD, Ortenblad N. Increased subsarcolemmal lipids in type 2 diabetes: effect of training on localization of lipids, mitochondria, and glycogen in sedentary human skeletal muscle. Am J Physiol Endocrinol Metab 2010; 298:E706-13. [PMID: 20028967 DOI: 10.1152/ajpendo.00692.2009] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The purpose of the study was to investigate the effect of aerobic training and type 2 diabetes on intramyocellular localization of lipids, mitochondria, and glycogen. Obese type 2 diabetic patients (n = 12) and matched obese controls (n = 12) participated in aerobic cycling training for 10 wk. Endurance-trained athletes (n = 15) were included for comparison. Insulin action was determined by euglycemic-hyperinsulinemic clamp. Intramyocellular contents of lipids, mitochondria, and glycogen at different subcellular compartments were assessed by transmission electron microscopy in biopsies obtained from vastus lateralis muscle. Type 2 diabetic patients were more insulin resistant than obese controls and had threefold higher volume of subsarcolemmal (SS) lipids compared with obese controls and endurance-trained subjects. No difference was found in intermyofibrillar lipids. Importantly, following aerobic training, this excess SS lipid volume was lowered by approximately 50%, approaching the levels observed in the nondiabetic subjects. A strong inverse association between insulin sensitivity and SS lipid volume was found (r(2)=0.62, P = 0.002). The volume density and localization of mitochondria and glycogen were the same in type 2 diabetic patients and control subjects, and showed in parallel with improved insulin sensitivity a similar increase in response to training, however, with a more pronounced increase in SS mitochondria and SS glycogen than in other localizations. In conclusion, this study, estimating intramyocellular localization of lipids, mitochondria, and glycogen, indicates that type 2 diabetic patients may be exposed to increased levels of SS lipids. Thus consideration of cell compartmentation may advance the understanding of the role of lipids in muscle function and type 2 diabetes.
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Affiliation(s)
- Joachim Nielsen
- Institute of Sports Science and Clinical Biomechanics, Univ. of Southern Denmark, Odense, Denmark.
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21
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Iozzo P, Lautamaki R, Borra R, Lehto HR, Bucci M, Viljanen A, Parkka J, Lepomaki V, Maggio R, Parkkola R, Knuuti J, Nuutila P. Contribution of glucose tolerance and gender to cardiac adiposity. J Clin Endocrinol Metab 2009; 94:4472-82. [PMID: 19820028 DOI: 10.1210/jc.2009-0436] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
CONTEXT AND OBJECTIVE To examine whether pericardial and myocardial fat depots may contribute to the association between diabetes and cardiovascular risk, including sex-related differences, and the role of adiponectin, we evaluated data in patients with obesity and without diabetes [nondiabetic (ND)] or with impaired glucose tolerance or type 2 diabetes and in lean ND controls. METHODS Magnetic resonance imaging and spectroscopy were used to measure left ventricular (LV) function and abdominal sc and visceral fat areas to estimate respective masses, pericardial fat depots, and myocardial triglyceride content in 53 subjects (10 lean ND, 25 obese ND, six impaired-glucose-tolerance, and 12 type 2 diabetic patients with macrovascular disease); gender effects and adiponectin levels were evaluated in the available subset of subjects. RESULTS Myocardial and pericardial fat increased progressively across study groups. They were lower in obese women than men (P = 0.002), but cardiac steatosis caught up in hyperglycemic women (+81% vs. ND, P = 0.01). Adiponectin was inversely related with both fat depots (P < 0.01) and LV mass (P = 0.003) and positively with LV function (P = 0.03). In multiple regression analysis, myocardial and pericardial fat were independently related with plasma glucose levels, only pericardial fat mass was associated with visceral adiposity and myocardial fat with cardiac output and work. CONCLUSIONS We conclude that glycemia, gender, adiponectin, and cardiac workload are associated with, and hyperglycemia and male gender are independent positive predictors of, heart adiposity. Once glucose tolerance becomes impaired, the evolution of cardiac steatosis is more pronounced in women.
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Affiliation(s)
- Patricia Iozzo
- Turku PET Centre, University of Turku, 20521 Turku, Finland.
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22
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Pearen MA, Ryall JG, Lynch GS, Muscat GE. Expression profiling of skeletal muscle following acute and chronic beta2-adrenergic stimulation: implications for hypertrophy, metabolism and circadian rhythm. BMC Genomics 2009; 10:448. [PMID: 19772666 PMCID: PMC2758907 DOI: 10.1186/1471-2164-10-448] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 09/23/2009] [Indexed: 02/08/2023] Open
Abstract
Background Systemic administration of β-adrenoceptor (β-AR) agonists has been found to induce skeletal muscle hypertrophy and significant metabolic changes. In the context of energy homeostasis, the importance of β-AR signaling has been highlighted by the inability of β1-3-AR-deficient mice to regulate energy expenditure and susceptibility to diet induced obesity. However, the molecular pathways and gene expression changes that initiate and maintain these phenotypic modulations are poorly understood. Therefore, the aim of this study was to identify differential changes in gene expression in murine skeletal muscle associated with systemic (acute and chronic) administration of the β2-AR agonist formoterol. Results Skeletal muscle gene expression (from murine tibialis anterior) was profiled at both 1 and 4 hours following systemic administration of the β2-AR agonist formoterol, using Illumina 46K mouse BeadArrays. Illumina expression profiling revealed significant expression changes in genes associated with skeletal muscle hypertrophy, myoblast differentiation, metabolism, circadian rhythm, transcription, histones, and oxidative stress. Differentially expressed genes relevant to the regulation of muscle mass and metabolism (in the context of the hypertrophic phenotype) were further validated by quantitative RT-PCR to examine gene expression in response to both acute (1-24 h) and chronic administration (1-28 days) of formoterol at multiple timepoints. In terms of skeletal muscle hypertrophy, attenuation of myostatin signaling (including differential expression of myostatin, activin receptor IIB, phospho-Smad3 etc) was observed following acute and chronic administration of formoterol. Acute (but not chronic) administration of formoterol also significantly induced the expression of genes involved in oxidative metabolism, including hexokinase 2, sorbin and SH3 domain containing 1, and uncoupling protein 3. Interestingly, formoterol administration also appeared to influence some genes associated with the peripheral regulation of circadian rhythm (including nuclear factor interleukin 3 regulated, D site albumin promoter binding protein, and cryptochrome 2). Conclusion This is the first study to utilize gene expression profiling to examine global gene expression in response to acute β2-AR agonist treatment of skeletal muscle. In summary, systemic administration of a β2-AR agonist had a profound effect on global gene expression in skeletal muscle. In terms of hypertrophy, β2-AR agonist treatment altered the expression of several genes associated with myostatin signaling, a previously unreported effect of β-AR signaling in skeletal muscle. This study also demonstrates a β2-AR agonist regulation of circadian rhythm genes, indicating crosstalk between β-AR signaling and circadian cycling in skeletal muscle. Gene expression alterations discovered in this study provides insight into many of the underlying changes in gene expression that mediate β-AR induced skeletal muscle hypertrophy and altered metabolism.
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Affiliation(s)
- Michael A Pearen
- Institute for Molecular Bioscience, The University of Queensland, Queensland 4072, Australia.
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Amengual J, Ribot J, Bonet ML, Palou A. Retinoic acid treatment increases lipid oxidation capacity in skeletal muscle of mice. Obesity (Silver Spring) 2008; 16:585-91. [PMID: 18239600 DOI: 10.1038/oby.2007.104] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE All-trans retinoic acid (ATRA), a carboxylic form of vitamin A, favors in mice a mobilization of body fat reserves that correlates with an increment of oxidative and thermogenic capacity in adipose tissues. The objective of this study has been to investigate the effect of ATRA treatment on skeletal muscle capacity for fatty-acid catabolism. METHODS AND PROCEDURES Tissue composition and gene expression related to lipid and oxidative metabolism were analyzed in skeletal muscle of mice acutely treated with ATRA or vehicle (olive oil). RESULTS ATRA treatment triggered a dose-dependent increase in the muscle mRNA expression levels of selected enzymes, transporters and transcription factors involved in fatty-acid oxidation, respiration, and thermogenesis namely: muscle-type carnitine palmitoyltransferase 1, acyl CoA oxidase 1, subunit II of cytochrome oxidase, uncoupling protein 3, peroxisome proliferator-activated receptor-gamma co-activator -1alpha and peroxisome proliferator-activated receptor-delta (PPARdelta). The treatment also resulted in the upregulation of the mRNA levels of acetyl-CoA carboxylase 2 (ACC2), a key regulatory enzyme for mitochondrial fatty-acid oxidation in muscle. Skeletal muscle protein levels of PPARdelta and retinoid X receptor gamma, a partner for many nuclear receptors involved in lipid metabolism, were increased after ATRA treatment. Muscle lipid content was decreased. DISCUSSION These results indicate that ATRA treatment increases the capacity of skeletal muscle for fatty-acid oxidation. Knowledge of nutrients or nutrient-derivatives capable of enhancing oxidative metabolism in muscle and other tissues can contribute to new avenues of prevention and treatment of obesity and related disorders.
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Affiliation(s)
- Jaume Amengual
- Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, Palma de Mallorca, Spain
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24
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Risérus U, Sprecher D, Johnson T, Olson E, Hirschberg S, Liu A, Fang Z, Hegde P, Richards D, Sarov-Blat L, Strum JC, Basu S, Cheeseman J, Fielding BA, Humphreys SM, Danoff T, Moore NR, Murgatroyd P, O'Rahilly S, Sutton P, Willson T, Hassall D, Frayn KN, Karpe F. Activation of peroxisome proliferator-activated receptor (PPAR)delta promotes reversal of multiple metabolic abnormalities, reduces oxidative stress, and increases fatty acid oxidation in moderately obese men. Diabetes 2008; 57:332-9. [PMID: 18024853 DOI: 10.2337/db07-1318] [Citation(s) in RCA: 256] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Pharmacological use of peroxisome proliferator-activated receptor (PPAR)delta agonists and transgenic overexpression of PPARdelta in mice suggest amelioration of features of the metabolic syndrome through enhanced fat oxidation in skeletal muscle. We hypothesize a similar mechanism operates in humans. RESEARCH DESIGN AND METHODS The PPARdelta agonist (10 mg o.d. GW501516), a comparator PPARalpha agonist (20 mug o.d. GW590735), and placebo were given in a double-blind, randomized, three-parallel group, 2-week study to six healthy moderately overweight subjects in each group. Metabolic evaluation was made before and after treatment including liver fat quantification, fasting blood samples, a 6-h meal tolerance test with stable isotope fatty acids, skeletal muscle biopsy for gene expression, and urinary isoprostanes for global oxidative stress. RESULTS Treatment with GW501516 showed statistically significant reductions in fasting plasma triglycerides (-30%), apolipoprotein B (-26%), LDL cholesterol (-23%), and insulin (-11%), whereas HDL cholesterol was unchanged. A 20% reduction in liver fat content (P < 0.05) and 30% reduction in urinary isoprostanes (P = 0.01) were also observed. Except for a lowering of triglycerides (-30%, P < 0.05), none of these changes were observed in response to GW590735. The relative proportion of exhaled CO(2) directly originating from the fat content of the meal was increased (P < 0.05) in response to GW501516, and skeletal muscle expression of carnitine palmitoyl-transferase 1b (CPT1b) was also significantly increased. CONCLUSIONS The PPARdelta agonist GW501516 reverses multiple abnormalities associated with the metabolic syndrome without increasing oxidative stress. The effect is probably caused by increased fat oxidation in skeletal muscle.
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St-Onge MP, Newcomer BR, Buchthal S, Aban I, Allison DB, Bosarge A, Gower B. Intramyocellular lipid content is lower with a low-fat diet than with high-fat diets, but that may not be relevant for health. Am J Clin Nutr 2007; 86:1316-22. [PMID: 17991641 DOI: 10.1093/ajcn/86.5.1316] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Fat deposition in muscle has been found to be related to metabolic risk. OBJECTIVE This study compared soleus intramyocellular lipid (IMCL) concentrations after consumption of weight-maintaining, controlled diets differing in total fat and fat type. DESIGN This study consisted of 3 phases of 25 d each in a crossover, controlled feeding design. The low-fat (LF) diet provided 30.8% and 5.2% of energy from fat and polyunsaturated fat (PUFA), respectively. Two higher-fat diets were tested: the high-fat (HF) diet provided 37.9% and 5.8% of energy from fat and PUFA, respectively, and the high-PUFA (HPUFA) diet provided 36.3% and 9.7% of energy from fat and PUFA, respectively. Twenty-four men and women [age range: 19-65 y; body mass index (in kg/m(2)): 20-35] whose LDL and glucose concentrations were between 130 and 180 mg/dL and <126 mg/dL, respectively, completed all study phases. RESULTS IMCL content was 1.88 times as high after the HF diet (P = 0.005) and 1.71 times as high after the HPUFA diet (P = 0.002) as after the LF diet. There was no significant correlation between percentage fat mass or waist circumference and IMCL content. With pooled data from all diets, there was no significant correlation between IMCL content and insulin or glucose concentration. There was no significant difference in IMCL content in subjects with or without the metabolic syndrome or in subjects with LDL particle pattern A or B. CONCLUSIONS Our results suggest that IMCL content is not modulated by dietary fat type but by total fat intake and that reducing fat intake effectively lowers IMCL. However, the metabolic implications of having lower IMCL concentrations are not clear.
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Affiliation(s)
- Marie-Pierre St-Onge
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL, USA.
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Huang X, Yang C, Luo Y, Jin C, Wang F, McKeehan WL. FGFR4 prevents hyperlipidemia and insulin resistance but underlies high-fat diet induced fatty liver. Diabetes 2007; 56:2501-10. [PMID: 17664243 DOI: 10.2337/db07-0648] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Fibroblast growth factor (FGF) family signaling largely controls cellular homeostasis through short-range intercell paracrine communication. Recently FGF15/19, 21, and 23 have been implicated in endocrine control of metabolic homeostasis. The identity and location of the FGF receptor isotypes that mediate these effects are unclear. The objective was to determine the role of FGFR4, an isotype that has been proposed to mediate an ileal FGF15/19 to hepatocyte FGFR4 axis in cholesterol homeostasis, in metabolic homeostasis in vivo. RESEARCH DESIGN AND METHODS FGFR4(-/-) mice-mice overexpressing constitutively active hepatic FGFR4--and FGFR4(-/-) with constitutively active hepatic FGFR4 restored in the liver were subjected to a normal and a chronic high-fat diet sufficient to result in obesity. Systemic and liver-specific metabolic phenotypes were then characterized. RESULTS FGFR4-deficient mice on a normal diet exhibited features of metabolic syndrome that include increased mass of white adipose tissue, hyperlipidemia, glucose intolerance, and insulin resistance, in addition to hypercholesterolemia. Surprisingly, the FGFR4 deficiency alleviated high-fat diet-induced fatty liver in obese mice, which is also a correlate of metabolic syndrome. Restoration of FGFR4, specifically in hepatocytes of FGFR4-deficient mice, decreased plasma lipid levels and restored the high-fat diet-induced fatty liver but failed to restore glucose tolerance and sensitivity to insulin. CONCLUSIONS FGFR4 plays essential roles in systemic lipid and glucose homeostasis. FGFR4 activity in hepatocytes that normally serves to prevent systemic hyperlipidemia paradoxically underlies the fatty liver disease associated with chronic high-fat intake and obesity.
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Affiliation(s)
- Xinqiang Huang
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, 2121 W. Holcombe Blvd., Houston, TX 77030, USA
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Spargo FJ, McGee SL, Dzamko N, Watt MJ, Kemp BE, Britton SL, Koch LG, Hargreaves M, Hawley JA. Dysregulation of muscle lipid metabolism in rats selectively bred for low aerobic running capacity. Am J Physiol Endocrinol Metab 2007; 292:E1631-6. [PMID: 17284571 DOI: 10.1152/ajpendo.00702.2006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
As substrate for evaluation of metabolic diseases, we developed novel rat models that contrast for endurance exercise capacity. Through two-way artificial selection, we created rodent phenotypes of intrinsically low-capacity runners (LCR) and high-capacity runners (HCR) that also differed markedly for cardiovascular and metabolic disease risk factors. Here, we determined skeletal muscle proteins with putative roles in lipid and carbohydrate metabolism to better understand the mechanisms underlying differences in whole body substrate handling between phenotypes. Animals (generation 16) differed for endurance running capacity by 295%. LCR animals had higher resting plasma glucose (6.58 +/- 0.45 vs. 6.09 +/- 0.45 mmol/l), insulin (0.48 +/- 0.03 vs. 0.32 +/- 0.02 ng/ml), nonesterified fatty acid (0.57 +/- 0.14 v 0.35 +/- 0.05 mM), and triglyceride (TG; 0.47 +/- 0.11 vs. 0.25 +/- 0.08 mmol/l) concentrations (all P < 0.05). Muscle TG (72.3 +/- 14.7 vs. 38.9 +/- 6.2 mmol/kg dry muscle wt; P < 0.05) and diacylglycerol (96 +/- 28 vs. 42 +/- 8 pmol/mg dry muscle wt; P < 0.05) contents were elevated in LCR vs. HCR rats. Accompanying the greater lipid accretion in LCR was increased fatty acid translocase/CD36 content (1,014 +/- 80 vs. 781 +/- 70 arbitrary units; P < 0.05) and reduced TG lipase activity (0.158 +/- 0.0125 vs. 0.274 +/- 0.018 mmol.min(-1).kg dry muscle wt(-1); P < 0.05). Muscle glycogen, GLUT4 protein, and basal phosphorylation states of AMP-activated protein kinase-alpha1, AMP-activated protein kinase-alpha2, and acetyl-CoA carboxylase were similar in LCR and HCR. In conclusion, rats with low intrinsic aerobic capacity demonstrate abnormalities in lipid-handling capacity. These disruptions may, in part, be responsible for the increased risk of metabolic disorders observed in this phenotype.
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Affiliation(s)
- Fiona J Spargo
- Exercise Metabolism Group, School of Medical Sciences, Australia
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Ahmadian M, Duncan RE, Jaworski K, Sarkadi-Nagy E, Sul HS. Triacylglycerol metabolism in adipose tissue. ACTA ACUST UNITED AC 2007; 2:229-237. [PMID: 19194515 DOI: 10.2217/17460875.2.2.229] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Triacylglycerol (TAG) in adipose tissue serves as the major energy storage form in higher eukaryotes. Obesity, resulting from excess white adipose tissue, has increased dramatically in recent years resulting in a serious public health problem. Understanding of adipocyte-specific TAG synthesis and hydrolysis is critical to the development of strategies to treat and prevent obesity and its closely associated diseases, for example, Type 2 diabetes, hypertension and atherosclerosis. In this review, we present an overview of the major enzymes in TAG synthesis and lipolysis, including the recent discovery of a novel adipocyte TAG hydrolase.
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Affiliation(s)
- Maryam Ahmadian
- University of California, Department of Nutritional Sciences & Toxicology, Berkeley, CA 94720, USA, Tel.: +1 510 642 3978; ;
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Fürnsinn C, Willson TM, Brunmair B. Peroxisome proliferator-activated receptor-delta, a regulator of oxidative capacity, fuel switching and cholesterol transport. Diabetologia 2007; 50:8-17. [PMID: 17119917 DOI: 10.1007/s00125-006-0492-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Accepted: 08/16/2006] [Indexed: 12/14/2022]
Abstract
Synthetic agonists of peroxisome proliferator-activated receptor (PPAR)-delta have shown a promising pharmacological profile in preclinical models of metabolic and cardiovascular disease. At present, the pharmaceutical development of these drugs exploits the potential to raise plasma HDL-cholesterol in animals and their insulin-sensitising and glucose-lowering properties. PPAR-delta agonists have also proven to be powerful research tools that have provided insights into the role of fatty acid metabolism in human physiology and disease. Activation of PPAR-delta induces the expression of genes important for cellular fatty acid combustion and an associated increase in whole-body lipid dissipation. The predominant target tissue in this regard is skeletal muscle, in which PPAR-delta activation regulates the oxidative capacity of the mitochondrial apparatus, switches fuel preference from glucose to fatty acids, and reduces triacylglycerol storage. These changes counter the characteristic derangements of insulin- resistant skeletal muscle but resemble the metabolic adaptation to regular physical exercise. Apart from effects on fuel turnover, there is evidence for direct antiatherogenic properties, because PPAR-delta activation increases cholesterol export and represses inflammatory gene expression in macrophages and atherosclerotic lesions. Whereas conclusions about the full potential of PPAR-delta as a drug target await the result of large scale clinical testing, ongoing investigation of this nuclear receptor has greatly improved our knowledge of the physiological regulation of whole-body fuel turnover and the interdependence of mitochondrial function and insulin sensitivity.
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Affiliation(s)
- C Fürnsinn
- Department of Medicine III, Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria.
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Abstract
Dragonflies infected with noninvasive gregarine gut parasites (Apicomplexa: Eugregarinorida) [corrected] have reduced flight-muscle performance, an inability to metabolize lipid in their muscles, twofold-elevated hemolymph carbohydrate concentrations, and they accumulate fat in their thorax in a manner analogous to mammalian obesity. Gregarine infection is associated with inappropriate responses of hemolymph carbohydrate concentration to insulin and with chronic activation in the flight muscles of p38 MAP kinase, a signaling molecule involved in immune and stress responses. Short-term exposure to gregarine excretory/secretory products caused elevated blood carbohydrate and p38 MAPK activation in healthy individuals. These characteristics comprise a set of symptoms and processes that are known in mammals as metabolic syndrome but which have not previously been described in other animal taxa. In addition to expanding the known taxonomic breadth of metabolic disease, these results indicate that insects may be useful experimental models for studying its underlying biology and mechanisms.
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Affiliation(s)
- Rudolf J Schilder
- Department of Biology, 208 Mueller Laboratory, Pennsylvania State University, University Park, PA 16802, USA.
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Kankaanpää M, Lehto HR, Pärkkä JP, Komu M, Viljanen A, Ferrannini E, Knuuti J, Nuutila P, Parkkola R, Iozzo P. Myocardial triglyceride content and epicardial fat mass in human obesity: relationship to left ventricular function and serum free fatty acid levels. J Clin Endocrinol Metab 2006; 91:4689-95. [PMID: 16926257 DOI: 10.1210/jc.2006-0584] [Citation(s) in RCA: 248] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
CONTEXT AND OBJECTIVE Ectopic fat accumulation within and around the myocardial wall has been implicated in the pathogenesis of heart disease in obesity. We evaluated myocardial and epicardial fat, left ventricular (LV) function, and metabolic risk factors in nine (five lean, four moderately obese) men. METHODS Myocardial fat percent was quantified in the septum by proton magnetic resonance spectroscopy. Reproducibility was assessed by triplicate systolic and diastolic measurements. LV parameters and epicardial fat were determined by magnetic resonance imaging. Waist-to-hip ratio and liver enzymes (alanine transaminase) were used as surrogate markers of visceral and liver fat contents. RESULTS Myocardial fat (2.1 +/- 0.5 vs. 0.8 +/- 0.1, P = 0.03) and epicardial fat (120 +/- 33 vs. 55 +/- 12 g, P = 0.08) were higher in obese than lean subjects. Individuals with above-median alanine transaminase values had a 4-fold elevation in myocardial fat. The coefficient of variation of repeated myocardial fat percent determinations was 17 +/- 3 and 23 +/- 3% in systole and diastole, respectively. Myocardial fat was correlated with free fatty acid (FFA) levels (r = 0.76; P = 0.017), epicardial fat (r = 0.69; P = 0.042), and waist-to-hip ratio (r = 0.70; P = 0.035), and it showed a tendency to associate positively with LV work. Epicardial fat was associated with peripheral vascular resistance (positively) and the cardiac index (negatively). FFA levels were significantly correlated with LV mass (r = 0.72; P = 0.030) and forward work (r = 0.74; P = 0.023). CONCLUSIONS/INTERPRETATION The accumulation of triglyceride in and around the myocardium of moderately obese individuals is significant, and it is related to FFA exposure, generalized ectopic fat excess, and peripheral vascular resistance. These changes precede LV overload and hypertrophy.
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Affiliation(s)
- Mikko Kankaanpää
- Turku PET Centre, University of Turku, FIN-20521, Turku, Finland
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Ukkola O. Operative risk factors in the metabolic syndrome: is it lipids and high blood pressure or are there direct vascular effects of insulin resistance and obesity? Curr Cardiol Rep 2006; 8:427-32. [PMID: 17059794 DOI: 10.1007/s11886-006-0100-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The metabolic syndrome is associated with an increased risk for cardiovascular disease. Dyslipidemia, high blood pressure, and impaired glucose tolerance, components of the metabolic syndrome, are all clearly atherogenic. Insulin resistance is an important correlate of other risk factors. Excess abdominal fat, as often seen in overweight people and commonly observed in obese individuals, is the single most important central feature of the metabolic syndrome. In addition to insulin resistance, an excess amount of abdominal fat is associated with all the features of metabolic clustering. Adipocytes secrete several peptide hormones that have been related to the metabolic syndrome and related cardiovascular disease. The role of traditional versus novel adipose tissue-related risk factors in the background of atherosclerosis in the metabolic syndrome are discussed.
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Affiliation(s)
- Olavi Ukkola
- Department of Internal Medicine and Biocenter Oulu, University of Oulu, Kajaanintie 50/P.O. Box 5000, Oulu, FIN-90014, Finland.
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Smith AG, Muscat GEO. Orphan nuclear receptors: therapeutic opportunities in skeletal muscle. Am J Physiol Cell Physiol 2006; 291:C203-17. [PMID: 16825600 DOI: 10.1152/ajpcell.00476.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Nuclear hormone receptors (NRs) are ligand-dependent transcription factors that bind DNA and translate physiological signals into gene regulation. The therapeutic utility of NRs is underscored by the diversity of drugs created to manage dysfunctional hormone signaling in the context of reproductive biology, inflammation, dermatology, cancer, and metabolic disease. For example, drugs that target nuclear receptors generate over $10 billion in annual sales. Almost two decades ago, gene products were identified that belonged to the NR superfamily on the basis of DNA and protein sequence identity. However, the endogenous and synthetic small molecules that modulate their action were not known, and they were denoted orphan NRs. Many of the remaining orphan NRs are highly enriched in energy-demanding major mass tissues, including skeletal muscle, brown and white adipose, brain, liver, and kidney. This review focuses on recently adopted and orphan NR function in skeletal muscle, a tissue that accounts for approximately 35% of the total body mass and energy expenditure, and is a major site of fatty acid and glucose utilization. Moreover, this lean tissue is involved in cholesterol efflux and secretes that control energy expenditure and adiposity. Consequently, muscle has a significant role in insulin sensitivity, the blood lipid profile, and energy balance. Accordingly, skeletal muscle plays a considerable role in the progression of dyslipidemia, diabetes, and obesity. These are risk factors for cardiovascular disease, which is the the foremost cause of global mortality (>16.7 million deaths in 2003). Therefore, it is not surprising that orphan NRs and skeletal muscle are emerging as therapeutic candidates in the battle against dyslipidemia, diabetes, obesity, and cardiovascular disease.
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Affiliation(s)
- Aaron G Smith
- Institute for Molecular Bioscience, Univ. of Queensland, St. Lucia 4072, Queensland, Australia.
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Debard C, Cozzone D, Ricard N, Vouillarmet J, Disse E, Husson B, Laville M, Vidal H. Short-term activation of peroxysome proliferator-activated receptor beta/delta increases fatty acid oxidation but does not restore insulin action in muscle cells from type 2 diabetic patients. J Mol Med (Berl) 2006; 84:747-52. [PMID: 16897074 DOI: 10.1007/s00109-006-0077-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Accepted: 03/29/2006] [Indexed: 12/25/2022]
Abstract
Defective fatty acid oxidation in skeletal muscle is one of the possible causes of insulin resistance. Peroxisome proliferator-activated receptor beta activators are strong inducers of fatty acid oxidation. The aim of this study was to verify whether activation of fatty acid oxidation by PPARbeta agonists in human skeletal muscle cells prepared from type 2 diabetic patients could improve the reduced responses to insulin that characterized this cell model. GW0742 (10 nM) significantly increased fatty acid oxidation and oxidative gene expression in myotubes prepared from both healthy subjects and type 2 diabetic patients. In cells from control subjects, incubation with the agonist for 48 h affected neither insulin-induced rate of glycogen synthesis nor the phosphorylation state of protein kinase B (PKB serine 473). Myotubes from type 2 diabetic patients displayed marked reduction in the effects of insulin on glycogen synthesis and on PKB phosphorylation. However, treatment with PPARbeta agonists did not restore these defects. Therefore, these results indicate that induction of fatty acid oxidation with PPARbeta activators during short-term exposition is not sufficient to correct for insulin resistance in muscle cells from type 2 diabetic patients. This suggests that additional studies are needed to better characterize the link between fatty acid oxidation and insulin sensitivity in humans.
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Affiliation(s)
- Cyrille Debard
- INSERM U-449, INRA U-1235, R. Laennec Faculty of Medicine, Human Nutrition Research Center, Claude Bernard-Lyon 1 University, Rue G. Paradin, 69372, Lyon, Cedex 08, France
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