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Chen X, Liu C, Zhang Y, Shao R, He J, Huang W, Liu Z. Regulating effects of phytosterol esters-loaded emulsions stabilized with green tea polysaccharide conjugates and Tween on lipids in KKAy mice. Int J Biol Macromol 2023:125235. [PMID: 37290551 DOI: 10.1016/j.ijbiomac.2023.125235] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/23/2023] [Accepted: 06/04/2023] [Indexed: 06/10/2023]
Abstract
Phytosterol esters (PSE) have been shown to have cholesterol-lowering effects, but their insolubility in water limits their applications. Green tea polysaccharide conjugates (gTPC) have hypoglycemic and emulsifying effects. To address lipid dysregulation in diabetic patients, we developed PSE-loaded emulsions stabilized with gTPC and Tween-20 (gTPC-PSE emulsions) and evaluated their physicochemical properties. We subsequently investigated the lipid-regulating potential of these emulsions to in KKAy mice. The KKAy mice were randomly assigned to eight groups: the model group, the Lipitor (10 mg·kg-1)-acarbose (30 mg·kg-1) combination group, two gTPC groups, two PSE groups, and two gTPC-PSE groups with a 1:2 mass ratio of gTPC to PSE. The administered doses were 90 and 270 mg kg-1, respectively. Administration of a 270 mg·kg-1 dose of gTPC-PSE emulsions led to the most significant effects including increased levels of liver and serum high-density lipoprotein cholesterol (HDL-CH), reduced serum leptin and insulin, and improved liver superoxide dismutase (SOD) and reduced malondialdehyde (MDA). In general, gTPC and PSE demonstrated a synergistic effect on lipid regulation in mice. Our results indicate that gTPC-PSE emulsions hold potential as a nutritional intervention for diabetes by modulating lipid levels.
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Affiliation(s)
- Xiaoqiang Chen
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China.
| | - Caixia Liu
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China
| | - Yuxue Zhang
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China
| | - Ruixiang Shao
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China
| | - Jun He
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China
| | - Wei Huang
- Hubei Institute for Drug Control, Wuhan 430075, China
| | - Zhong Liu
- Hubei August Flower Food Co. LTD, Xianning 437000, China
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Ma XY, Chen FQ. Effects of anti-diabetic drugs on sarcopenia: Best treatment options for elderly patients with type 2 diabetes mellitus and sarcopenia. World J Clin Cases 2021; 9:10064-10074. [PMID: 34904076 PMCID: PMC8638038 DOI: 10.12998/wjcc.v9.i33.10064] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/22/2021] [Accepted: 09/30/2021] [Indexed: 02/06/2023] Open
Abstract
Human life expectancy increases as society becomes more developed. This increased life expectancy poses challenges associated with the rapid aging of the population. Sarcopenia, an age-related disease, has become a worldwide health issue. Patients with sarcopenia experience decreases in muscle mass and function, becoming frail and eventually bedridden. Type 2 diabetes mellitus (T2DM) is also a major health issue; the incidence of T2DM increases with aging. T2DM is associated with reduced muscle strength and poor muscle quality and may contribute to acceleration of the aging process, augmenting age-related sarcopenia. Recent studies indicate that elderly patients with diabetes are at an increased risk for sarcopenia. Therefore, these older diabetic patients with sarcopenia need specific anti-diabetic therapies targeting not only glycemic control but also sarcopenia, with the goal of preventing sarcopenia in pre-sarcopenic patients. Presently, various types of hypoglycemic drugs are available, but which hypoglycemic drugs are better suited for geriatric T2DM patients with sarcopenia remains undetermined. In this review, we discuss the association between diabetes and sarcopenia in geriatric patients, and how anti-diabetic drugs may influence sarcopenia outcomes. This review will guide clinical workers in the selection of drugs best suited for this patient population.
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Affiliation(s)
- Xiao-Yu Ma
- Department of Geriatrics, The First Affiliated Hospital, China Medical University, Shenyang 110001, Liaoning Province, China
| | - Fen-Qin Chen
- Department of Geriatrics, The First Affiliated Hospital, China Medical University, Shenyang 110001, Liaoning Province, China
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Tang H, Zeng Q, Tang T, Wei Y, Pu P. Kaempferide improves glycolipid metabolism disorder by activating PPARγ in high-fat-diet-fed mice. Life Sci 2021; 270:119133. [PMID: 33508298 DOI: 10.1016/j.lfs.2021.119133] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/14/2021] [Accepted: 01/19/2021] [Indexed: 12/13/2022]
Abstract
AIMS Kaempferide (Ka, 3,5,7-trihydroxy-4'-methoxyflavone), an active ingredient of Tagetes erecta L., has been demonstrated to possess many pharmacological effects, including antioxidant, anti-inflammation, anticancer and antihypertension in previous study. However, there is no evidence of Ka on metabolic disorder in former studies. This study investigated the effects of Ka on glycolipid metabolism and explored the underlying mechanisms of action in vivo and vitro. MATERIALS AND METHODS The mouse model of glycolipid metabolism disorder was induced by high-fat diet (HFD). The effects of Ka were evaluated on bodyweight, lipid metabolism and glucose metabolism. Hypolipidemic effect was examined by blood sample analysis. The hypoglycemic effect was detected by several indicators, like blood glucose, serum insulin, HOMA index and intraperitoneal glucose tolerance tests (IPGTT). The signaling pathways of lipid metabolism (PPARγ/LXRα/ABCA1) and glucose metabolism (PPARγ/PI3K/AKT) were evaluated using Real-Time PCR and Western blot. The primary culture of hepatocyte was prepared to confirm the target of Ka by co-culturing with PPARγ agonist or inhibitor. KEY FINDINGS The HFD mice developed obesity, hyperlipidemia, hyperglycemia and insulin resistance. Administration of Ka at a dose of 10 mg/kg.BW for 16 weeks effectively attenuated these changes. Further studies revealed the hypolipidemic and hypoglycemic effects of Ka depended on the activation of PPARγ/LXRα/ABCA1 and PPARγ/PI3K/AKT pathways, respectively. The primary hepatocyte test, co-cultured with PPARγ agonists or inhibitors, further confirmed the above signaling pathway and key protein. SIGNIFICANCE These results suggested that Ka played an important role in improving glycolipid metabolism disorder. These favorable effects were causally associated with anti-obesity. The underlying mechanisms might have to do with the activation of the PPARγ and its downstream signaling pathway. Our study helped to understand the pharmacological actions of Ka, and played a role for Ka in the effective treatment of obesity, diabetes, nonalcoholic hepatitis and other metabolic diseases.
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Affiliation(s)
- Heng Tang
- Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, No.1 Youyi Road, Yuanjiagang, Yuzhong District, Chongqing 400042, China
| | - Qingfu Zeng
- Department of Vascular Surgery, The Second Affiliated Hospital of Nanchang University, No. 1, Minde Road, Donghu District, Nanchang City, Jiangxi Province 330006, China
| | - Ting Tang
- Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, No.1 Youyi Road, Yuanjiagang, Yuzhong District, Chongqing 400042, China
| | - Yunjie Wei
- Department of Cardiology, Hubei Shiyan Taihe hospital, Hubei, China
| | - Peng Pu
- Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, No.1 Youyi Road, Yuanjiagang, Yuzhong District, Chongqing 400042, China.
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4
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Djouadi F, Bastin J. Mitochondrial Genetic Disorders: Cell Signaling and Pharmacological Therapies. Cells 2019; 8:cells8040289. [PMID: 30925787 PMCID: PMC6523966 DOI: 10.3390/cells8040289] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/19/2019] [Accepted: 03/23/2019] [Indexed: 12/19/2022] Open
Abstract
Mitochondrial fatty acid oxidation (FAO) and respiratory chain (RC) defects form a large group of inherited monogenic disorders sharing many common clinical and pathophysiological features, including disruption of mitochondrial bioenergetics, but also, for example, oxidative stress and accumulation of noxious metabolites. Interestingly, several transcription factors or co-activators exert transcriptional control on both FAO and RC genes, and can be activated by small molecules, opening to possibly common therapeutic approaches for FAO and RC deficiencies. Here, we review recent data on the potential of various drugs or small molecules targeting pivotal metabolic regulators: peroxisome proliferator activated receptors (PPARs), sirtuin 1 (SIRT1), AMP-activated protein kinase (AMPK), and protein kinase A (PKA)) or interacting with reactive oxygen species (ROS) signaling, to alleviate or to correct inborn FAO or RC deficiencies in cellular or animal models. The possible molecular mechanisms involved, in particular the contribution of mitochondrial biogenesis, are discussed. Applications of these pharmacological approaches as a function of genotype/phenotype are also addressed, which clearly orient toward personalized therapy. Finally, we propose that beyond the identification of individual candidate drugs/molecules, future pharmacological approaches should consider their combination, which could produce additive or synergistic effects that may further enhance their therapeutic potential.
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Affiliation(s)
- Fatima Djouadi
- Centre de Recherche des Cordeliers, INSERM U1138, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, F-75006 Paris, France.
| | - Jean Bastin
- Centre de Recherche des Cordeliers, INSERM U1138, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, F-75006 Paris, France.
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Divakaruni AS, Hsieh WY, Minarrieta L, Duong TN, Kim KKO, Desousa BR, Andreyev AY, Bowman CE, Caradonna K, Dranka BP, Ferrick DA, Liesa M, Stiles L, Rogers GW, Braas D, Ciaraldi TP, Wolfgang MJ, Sparwasser T, Berod L, Bensinger SJ, Murphy AN. Etomoxir Inhibits Macrophage Polarization by Disrupting CoA Homeostasis. Cell Metab 2018; 28:490-503.e7. [PMID: 30043752 PMCID: PMC6125190 DOI: 10.1016/j.cmet.2018.06.001] [Citation(s) in RCA: 223] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 04/20/2018] [Accepted: 06/02/2018] [Indexed: 12/12/2022]
Abstract
Long-chain fatty acid (LCFA) oxidation has been shown to play an important role in interleukin-4 (IL-4)-mediated macrophage polarization (M(IL-4)). However, many of these conclusions are based on the inhibition of carnitine palmitoyltransferase-1 with high concentrations of etomoxir that far exceed what is required to inhibit enzyme activity (EC90 < 3 μM). We employ genetic and pharmacologic models to demonstrate that LCFA oxidation is largely dispensable for IL-4-driven polarization. Unexpectedly, high concentrations of etomoxir retained the ability to disrupt M(IL-4) polarization in the absence of Cpt1a or Cpt2 expression. Although excess etomoxir inhibits the adenine nucleotide translocase, oxidative phosphorylation is surprisingly dispensable for M(IL-4). Instead, the block in polarization was traced to depletion of intracellular free coenzyme A (CoA), likely resulting from conversion of the pro-drug etomoxir into active etomoxiryl CoA. These studies help explain the effect(s) of excess etomoxir on immune cells and reveal an unappreciated role for CoA metabolism in macrophage polarization.
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Affiliation(s)
- Ajit S Divakaruni
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Wei Yuan Hsieh
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Lucía Minarrieta
- Institute of Infection Immunology, TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture Between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
| | - Tin N Duong
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kristen K O Kim
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Brandon R Desousa
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Alexander Y Andreyev
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Caitlyn E Bowman
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Kacey Caradonna
- Agilent Technologies, 5301 Stevens Creek Boulevard, Santa Clara, CA 95051, USA
| | - Brian P Dranka
- Agilent Technologies, 5301 Stevens Creek Boulevard, Santa Clara, CA 95051, USA
| | - David A Ferrick
- Agilent Technologies, 5301 Stevens Creek Boulevard, Santa Clara, CA 95051, USA
| | - Marc Liesa
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Linsey Stiles
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - George W Rogers
- Agilent Technologies, 5301 Stevens Creek Boulevard, Santa Clara, CA 95051, USA
| | - Daniel Braas
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA; UCLA Metabolomics Center and Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Theodore P Ciaraldi
- Veterans Affairs San Diego Healthcare System, La Jolla, CA 92161, USA; Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Michael J Wolfgang
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Tim Sparwasser
- Institute of Infection Immunology, TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture Between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
| | - Luciana Berod
- Institute of Infection Immunology, TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture Between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
| | - Steven J Bensinger
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Anne N Murphy
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
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Abstract
The heart utilizes large amounts of fatty acids as energy providing substrates. The physiological balance of lipid uptake and oxidation prevents accumulation of excess lipids. Several processes that affect cardiac function, including ischemia, obesity, diabetes mellitus, sepsis, and most forms of heart failure lead to altered fatty acid oxidation and often also to the accumulation of lipids. There is now mounting evidence associating certain species of these lipids with cardiac lipotoxicity and subsequent myocardial dysfunction. Experimental and clinical data are discussed and paths to reduction of toxic lipids as a means to improve cardiac function are suggested.
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Affiliation(s)
- P Christian Schulze
- From the Divisions of Cardiology, Friedrich-Schiller-University Jena, Germany, and Columbia University, New York, NY (P.C.S.); Metabolic Biology Laboratory, Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA (K.D.); and Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, New York University School of Medicine, New York, NY (I.J.G.).
| | - Konstantinos Drosatos
- From the Divisions of Cardiology, Friedrich-Schiller-University Jena, Germany, and Columbia University, New York, NY (P.C.S.); Metabolic Biology Laboratory, Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA (K.D.); and Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, New York University School of Medicine, New York, NY (I.J.G.)
| | - Ira J Goldberg
- From the Divisions of Cardiology, Friedrich-Schiller-University Jena, Germany, and Columbia University, New York, NY (P.C.S.); Metabolic Biology Laboratory, Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA (K.D.); and Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, New York University School of Medicine, New York, NY (I.J.G.)
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Is the Mouse a Good Model of Human PPARγ-Related Metabolic Diseases? Int J Mol Sci 2016; 17:ijms17081236. [PMID: 27483259 PMCID: PMC5000634 DOI: 10.3390/ijms17081236] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 07/19/2016] [Accepted: 07/21/2016] [Indexed: 12/21/2022] Open
Abstract
With the increasing number of patients affected with metabolic diseases such as type 2 diabetes, obesity, atherosclerosis and insulin resistance, academic researchers and pharmaceutical companies are eager to better understand metabolic syndrome and develop new drugs for its treatment. Many studies have focused on the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ), which plays a crucial role in adipogenesis and lipid metabolism. These studies have been able to connect this transcription factor to several human metabolic diseases. Due to obvious limitations concerning experimentation in humans, animal models—mainly mouse models—have been generated to investigate the role of PPARγ in different tissues. This review focuses on the metabolic features of human and mouse PPARγ-related diseases and the utility of the mouse as a model.
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Altered Myokine Secretion Is an Intrinsic Property of Skeletal Muscle in Type 2 Diabetes. PLoS One 2016; 11:e0158209. [PMID: 27453994 PMCID: PMC4959771 DOI: 10.1371/journal.pone.0158209] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 06/13/2016] [Indexed: 01/05/2023] Open
Abstract
Skeletal muscle secretes factors, termed myokines. We employed differentiated human skeletal muscle cells (hSMC) cultured from Type 2 diabetic (T2D) and non-diabetic (ND) subjects to investigate the impact of T2D on myokine secretion. Following 24 hours of culture concentrations of selected myokines were determined to range over 4 orders of magnitude. T2D hSMC released increased amounts of IL6, IL8, IL15, TNFa, Growth Related Oncogene (GRO)a, monocyte chemotactic protein (MCP)-1, and follistatin compared to ND myotubes. T2D and ND hSMC secreted similar levels of IL1ß and vascular endothelial growth factor (VEGF). Treatment with the inflammatory agents lipopolysaccharide (LPS) or palmitate augmented the secretion of many myokines including: GROa, IL6, IL8, IL15, and TNFa, but did not consistently alter the protein content and/or phosphorylation of IkBa, p44/42 MAPK, p38 MAPK, c-Jun N-terminal kinase (JNK) and NF-kB, nor lead to consistent changes in basal and insulin-stimulated glucose uptake or free fatty acid oxidation. Conversely, treatment with pioglitazone or oleate resulted in modest reductions in the secretion of several myokines. Our results demonstrate that altered secretion of a number of myokines is an intrinsic property of skeletal muscle in T2D, suggesting a putative role of myokines in the response of skeletal muscle to T2D.
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Keane J, Tajouri L, Gray B. Recombinant human growth hormone and insulin-like growth factor-1 do not affect mitochondrial derived highly reactive oxygen species production in peripheral blood mononuclear cells under conditions of substrate saturation in-vitro. Nutr Metab (Lond) 2016; 13:45. [PMID: 27382409 PMCID: PMC4932701 DOI: 10.1186/s12986-016-0105-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 06/30/2016] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The purpose of this study was to investigate the mitochondrial effects exerted by physiological and supra-physiological concentrations of recombinant human growth hormone (rhGH) and recombinant insulin-like growth factor-1 (rIGF-1) under conditions of substrate saturation in peripheral blood mononuclear cells (PBMCs). METHODS PBMCs from healthy male subjects were treated with either rhGH, at concentrations of 0.5, 5 and 50 μg/L, or rIGF-1 at concentrations of 100, 300 and 500 μg/L for 4 h. Mitochondrial membrane potential (Δψm) and mitochondrial levels of highly reactive oxygen species (hROS) were subsequently analysed. This analysis was performed by flow cytometry in digitonin permeabilized cells, following treatment with saturating concentrations of various respiratory substrate combinations and the use of specific electron transport chain (ETC.) complex inhibitors, enabling control over both the sites of electron entry into the ETC. at complexes I and II and the entry of electrons from reduced carriers involved in β-oxidation at the level of ubiquinol. RESULTS Neither rhGH nor rIGF-1 exerted any significant effect on Δψm or the rate of hROS production in either lymphocyte or monocyte sub-populations under any of the respiratory conditions analysed. CONCLUSION That neither hormone was capable of attenuating levels of oxidative stress mediated via either complex I linked respiration or lipid-derived respiration could have serious health implications for the use of rhGH in healthy individuals, which is frequently associated with significant increases in the bioavailability of free fatty acids (FFA). Such elevated supplies of lipid-derived substrates to the mitochondria could lead to oxidative damage which would negatively impact mitochondrial function.
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Affiliation(s)
- James Keane
- Faculty of Health Sciences and Medicine, Bond University, Gold Coast, Queensland Australia
| | - Lotti Tajouri
- Faculty of Health Sciences and Medicine, Bond University, Gold Coast, Queensland Australia
| | - Bon Gray
- Faculty of Health Sciences and Medicine, Bond University, Gold Coast, Queensland Australia
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10
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Kim JC. The effect of exercise training combined with PPARγ agonist on skeletal muscle glucose uptake and insulin sensitivity in induced diabetic obese Zucker rats. J Exerc Nutrition Biochem 2016; 20:42-50. [PMID: 27508153 PMCID: PMC4977909 DOI: 10.20463/jenb.2016.06.20.2.6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 06/02/2016] [Accepted: 06/09/2016] [Indexed: 12/25/2022] Open
Abstract
[Purpose] Exercise training with PPARγ agonist is expected to increase glucose uptake and improve insulin sensitivity in skeletal muscle of patients with diabetes. However, its mechanisms to effect glucose uptake and insulin sensitivity in skeletal muscle are unclear. [Methods] The mechanism of action was determined by co-treatment with PPARγ agonist- rosiglitazone and exercise training in streptozotocin induced-diabetic obese Zucker rats. Exercise training was carried out for 6 weeks (swimming, 1 h/day, 5 times/week, 5% weight/g, 32±1℃) with rosiglitazone treatment (3mg/kg/day, 6weeks). [Results] Glucose uptake and insulin sensitivity was decreased in diabetic than normal animals. Exercise training and rosiglitazone treatment respectively increased the expression of PPAR(peroxisome proliferators-activated receptor)-α, -β/δ, -γ, PGC-1α(PPAR-γ coactivator-1α), adiponectin, GLUT-4(glucose transportor-4) and p-AMPK-α2(phospho-AMP activated protein kinase-α2) in EDL and SOL of diabetic, as compared to normal animals. Interestingly, training combined with rosiglitazone significantly increased glucose uptake and insulin sensitivity, which resulted in high expression of all molecules in diabetic than all other groups. [Conclusion] These results indicated that exercise training combined with rosiglitazone might mediate regulation of glucose uptake and insulin sensitivity in skeletal muscle. Therefore, exercise training combined with rosiglitazone may be recommended as complementary therapies for diabetes.
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Affiliation(s)
- Jae-Cheol Kim
- Department of Sports Science, College of Natural Science, Chonbuk National University, Jeonju Republic of Korea
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11
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Ergosterol Alleviates Kidney Injury in Streptozotocin-Induced Diabetic Mice. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 2015:691594. [PMID: 26664454 PMCID: PMC4664816 DOI: 10.1155/2015/691594] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/29/2015] [Accepted: 10/29/2015] [Indexed: 02/07/2023]
Abstract
Ergosterol (ERG) has been widely used in the development of novel drugs due to its unique physiological function. However, little is known about the protective effects of ERG on diabetes. Hence, the current study was designed to evaluate the positive role of ergosterol on streptozotocin- (STZ-) induced diabetes in mice. Oral glucose tolerance test (OGTT) was carried out to assess blood glucose level. Biochemical parameters such as uric acid, creatinine, serum insulin, triglycerides (TG), and total cholesterol (TC) were also measured. Pathological condition of kidney was examined by hematoxylin-eosin (H&E) staining. The expressions of PI3K, p-PI3K, Akt, p-Akt, NF-κBp65, p-NF-κBp65, IκBα, and p-IκBα were analyzed by western blot. ERG significantly reduced the concentrations of blood glucose, uric acid, creatinine, TG, and TC. Serum insulin was elevated with ERG treatment. In addition, renal pathologic changes of diabetes mice were also alleviated by ERG. Obtained data revealed that ERG restored the levels of PI3K/Akt/NF-κB signaling-related proteins in comparison with diabetes mice. Above all, it could be assumed that ERG might play a positive role in regulating STZ-induced diabetes through suppressing PI3K/Akt/NF-κB pathway.
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12
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Janssens S, Jonkers RAM, Groen AK, Nicolay K, van Loon LJC, Prompers JJ. Effects of acute exercise on lipid content and dietary lipid uptake in liver and skeletal muscle of lean and diabetic rats. Am J Physiol Endocrinol Metab 2015; 309:E874-83. [PMID: 26419590 DOI: 10.1152/ajpendo.00292.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/26/2015] [Indexed: 12/24/2022]
Abstract
Insulin resistance is associated with ectopic lipid accumulation. Physical activity improves insulin sensitivity, but the impact of exercise on lipid handling in insulin-resistant tissues remains to be elucidated. The present study characterizes the effects of acute exercise on lipid content and dietary lipid partitioning in liver and skeletal muscle of lean and diabetic rats by use of magnetic resonance spectroscopy (MRS). After baseline measurements, rats were randomized to exercise or no-exercise groups. A subset of animals was subjected to MRS directly after 1 h of treadmill running for measurement of total intrahepatocellular lipid (IHCL) and intramyocellular lipid (IMCL) content (n=7 lean and diabetic rats). The other animals were administered 13C-labeled lipids orally after treadmill visit (with or without exercise) followed by MRS measurements after 4 and 24 h to determine the 13C enrichment of IHCL and IMCL (n=8 per group). Total IHCL and IMCL content were fivefold higher in diabetic vs. lean rats (P<0.001). Exercise did not significantly affect IHCL content but reduced IMCL by 25±7 and 33±4% in lean and diabetic rats (P<0.05), respectively. Uptake of dietary lipids in liver and muscle was 2.3-fold greater in diabetic vs. lean rats (P<0.05). Prior exercise did not significantly modulate dietary lipid uptake into muscle, but in liver of both lean and diabetic rats, lipid uptake was 44% reduced after acute exercise (P<0.05). In conclusion, IMCL but not IHCL represents a viable substrate source during exercise in both lean and diabetic rats, and exercise differentially affects dietary lipid uptake in muscle and liver.
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Affiliation(s)
- Sharon Janssens
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; The Netherlands Consortium for Systems Biology, Den Haag, The Netherlands
| | - Richard A M Jonkers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Albert K Groen
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; and Department of Laboratory Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Klaas Nicolay
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Luc J C van Loon
- NUTRIM, School for Nutrition, Toxicology and Metabolism, Department of Human Movement Sciences, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Jeanine J Prompers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands;
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Jan M, Medh JD. ShRNA-mediated gene silencing of lipoprotein lipase improves insulin sensitivity in L6 skeletal muscle cells. Biochem Biophys Res Commun 2015; 462:33-7. [PMID: 25931001 DOI: 10.1016/j.bbrc.2015.04.098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 04/20/2015] [Indexed: 12/25/2022]
Abstract
In previous studies, we demonstrated that down-regulation of lipoprotein lipase in L6 muscle cells increased insulin-stimulated glucose uptake. In the current study, we used RNA interference technology to silence the LPL gene in L6 cells and generate a LPL-knock-down (LPL-KD) cell line. ShRNA transfected cells showed a 88% reduction in the level of LPL expression. The metabolic response to insulin was compared in wild-type (WT) and LPL-KD cells. Insulin-stimulated glycogen synthesis and glucose oxidation were respectively, 2.4-fold and 2.6-fold greater in LPL-KD cells compared to WT cells. Oxidation of oleic acid was reduced by 50% in LPL-KD cells compared to WT cells even in the absence of insulin. The contribution of LPL in regulating fuel metabolism was confirmed by adding back purified LPL to the culture media of LPL-KD cells. The presence of 10 μg/mL LPL resulted in LPL-KD cells reverting back to lower glycogen synthesis and glucose oxidation and increased fatty acid oxidation. Thus, LPL depletion appeared to mimic the action of insulin. These finding suggests an inverse correlation between muscle LPL levels and insulin-stimulated fuel homeostasis.
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Affiliation(s)
- Majib Jan
- Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330-8262, USA
| | - Jheem D Medh
- Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330-8262, USA.
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Huang M, Wang F, Zhou X, Yang H, Wang Y. Hypoglycemic and hypolipidemic properties of polysaccharides from Enterobacter cloacae Z0206 in KKAy mice. Carbohydr Polym 2015; 117:91-98. [DOI: 10.1016/j.carbpol.2014.09.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 08/11/2014] [Accepted: 09/07/2014] [Indexed: 12/25/2022]
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Multi-tissue computational modeling analyzes pathophysiology of type 2 diabetes in MKR mice. PLoS One 2014; 9:e102319. [PMID: 25029527 PMCID: PMC4100879 DOI: 10.1371/journal.pone.0102319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 06/18/2014] [Indexed: 12/25/2022] Open
Abstract
Computational models using metabolic reconstructions for in silico simulation of metabolic disorders such as type 2 diabetes mellitus (T2DM) can provide a better understanding of disease pathophysiology and avoid high experimentation costs. There is a limited amount of computational work, using metabolic reconstructions, performed in this field for the better understanding of T2DM. In this study, a new algorithm for generating tissue-specific metabolic models is presented, along with the resulting multi-confidence level (MCL) multi-tissue model. The effect of T2DM on liver, muscle, and fat in MKR mice was first studied by microarray analysis and subsequently the changes in gene expression of frank T2DM MKR mice versus healthy mice were applied to the multi-tissue model to test the effect. Using the first multi-tissue genome-scale model of all metabolic pathways in T2DM, we found out that branched-chain amino acids' degradation and fatty acids oxidation pathway is downregulated in T2DM MKR mice. Microarray data showed low expression of genes in MKR mice versus healthy mice in the degradation of branched-chain amino acids and fatty-acid oxidation pathways. In addition, the flux balance analysis using the MCL multi-tissue model showed that the degradation pathways of branched-chain amino acid and fatty acid oxidation were significantly downregulated in MKR mice versus healthy mice. Validation of the model was performed using data derived from the literature regarding T2DM. Microarray data was used in conjunction with the model to predict fluxes of various other metabolic pathways in the T2DM mouse model and alterations in a number of pathways were detected. The Type 2 Diabetes MCL multi-tissue model may explain the high level of branched-chain amino acids and free fatty acids in plasma of Type 2 Diabetic subjects from a metabolic fluxes perspective.
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Xiong WT, Gu L, Wang C, Sun HX, Liu X. Anti-hyperglycemic and hypolipidemic effects of Cistanche tubulosa in type 2 diabetic db/db mice. JOURNAL OF ETHNOPHARMACOLOGY 2013; 150:935-945. [PMID: 24095831 DOI: 10.1016/j.jep.2013.09.027] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 07/22/2013] [Accepted: 09/10/2013] [Indexed: 06/02/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The dried succulent stem of Cistanche tubulosa (Schenk) R. Wight is one component of traditional Chinese medicine prescriptions for diabetes. However, there have been no modern scientific reports to confirm this traditional claim for the Cistanche species until now. Thus, we investigated the effects of Cistanche tubulosa on glucose homeostasis and serum lipids in male BKS.Cg-Dock7(m) +/+ Lepr(db)/J (db/db) mice, a model of type 2 diabetes. MATERIALS AND METHODS The verbascoside and echinacoside contents of Cistanche tubulosa powder were evaluated using HPLC. The total phenolic content, polysaccharide content and antioxidant activity of Cistanche tubulosa powder were also evaluated. Then, different doses of Cistanche tubulosa (equivalent to 120.9, 72.6 or 24.2mg verbascoside/kg) were administered orally once daily for 45 days to male db/db mice. Age matched db/+ mice were used as normal controls. Body weight, fasting blood glucose, postprandial blood glucose and insulin tolerance test were measured during the experiment. At the time of sacrifice, blood was collected for measurement of insulin level, the homeostatic model assessment of insulin resistance (HOMA-IR), and total cholesterol, triglyceride, HDL-c, LDL-c and VLDL-c levels; liver and muscle were harvested for measurement of glycogen levels. RESULTS Cistanche tubulosa significantly suppressed the elevated fasting blood glucose and postprandial blood glucose levels, improved insulin resistance and dyslipidemia, and suppressed body weight loss in db/db mice. However, Cistanche tubulosa did not significantly affect serum insulin levels or hepatic and muscle glycogen levels. CONCLUSION This study provides scientific evidence for the traditional use of Cistanche tubulosa to treat diabetes, suggesting that Cistanche tubulosa has the potential for development into a functional food ingredient or drug to prevent hyperglycemia and treat hyperlipidemia.
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Affiliation(s)
- Wen-Ting Xiong
- Food and Health Engineering Research Center of State Education Ministry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, PR China.
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Roberts CK, Hevener AL, Barnard RJ. Metabolic syndrome and insulin resistance: underlying causes and modification by exercise training. Compr Physiol 2013; 3:1-58. [PMID: 23720280 DOI: 10.1002/cphy.c110062] [Citation(s) in RCA: 270] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Metabolic syndrome (MS) is a collection of cardiometabolic risk factors that includes obesity, insulin resistance, hypertension, and dyslipidemia. Although there has been significant debate regarding the criteria and concept of the syndrome, this clustering of risk factors is unequivocally linked to an increased risk of developing type 2 diabetes and cardiovascular disease. Regardless of the true definition, based on current population estimates, nearly 100 million have MS. It is often characterized by insulin resistance, which some have suggested is a major underpinning link between physical inactivity and MS. The purpose of this review is to: (i) provide an overview of the history, causes and clinical aspects of MS, (ii) review the molecular mechanisms of insulin action and the causes of insulin resistance, and (iii) discuss the epidemiological and intervention data on the effects of exercise on MS and insulin sensitivity.
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Affiliation(s)
- Christian K Roberts
- Exercise and Metabolic Disease Research Laboratory, Translational Sciences Section, School of Nursing, University of California at Los Angeles, Los Angeles, California, USA.
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Abstract
Diabetes and obesity are both associated with lipotoxic cardiomyopathy exclusive of coronary artery disease and hypertension. Lipotoxicities have become a public health concern and are responsible for a significant portion of clinical cardiac disease. These abnormalities may be the result of a toxic metabolic shift to more fatty acid and less glucose oxidation with concomitant accumulation of toxic lipids. Lipids can directly alter cellular structures and activate downstream pathways leading to toxicity. Recent data have implicated fatty acids and fatty acyl coenzyme A, diacylglycerol, and ceramide in cellular lipotoxicity, which may be caused by apoptosis, defective insulin signaling, endoplasmic reticulum stress, activation of protein kinase C, MAPK activation, or modulation of PPARs.
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Aas V, Bakke SS, Feng YZ, Kase ET, Jensen J, Bajpeyi S, Thoresen GH, Rustan AC. Are cultured human myotubes far from home? Cell Tissue Res 2013; 354:671-82. [PMID: 23749200 DOI: 10.1007/s00441-013-1655-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 05/03/2013] [Indexed: 12/25/2022]
Abstract
Satellite cells can be isolated from skeletal muscle biopsies, activated to proliferating myoblasts and differentiated into multinuclear myotubes in culture. These cell cultures represent a model system for intact human skeletal muscle and can be modulated ex vivo. The advantages of this system are that the most relevant genetic background is available for the investigation of human disease (as opposed to rodent cell cultures), the extracellular environment can be precisely controlled and the cells are not immortalized, thereby offering the possibility of studying innate characteristics of the donor. Limitations in differentiation status (fiber type) of the cells and energy metabolism can be improved by proper treatment, such as electrical pulse stimulation to mimic exercise. This review focuses on the way that human myotubes can be employed as a tool for studying metabolism in skeletal muscles, with special attention to changes in muscle energy metabolism in obesity and type 2 diabetes.
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Affiliation(s)
- Vigdis Aas
- Institute of Pharmacy and Biomedical Laboratory Science, Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, Oslo, Norway,
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Drosatos K, Khan RS, Trent CM, Jiang H, Son NH, Blaner WS, Homma S, Schulze PC, Goldberg IJ. Peroxisome proliferator-activated receptor-γ activation prevents sepsis-related cardiac dysfunction and mortality in mice. Circ Heart Fail 2013; 6:550-62. [PMID: 23572494 DOI: 10.1161/circheartfailure.112.000177] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Cardiac dysfunction with sepsis is associated with both inflammation and reduced fatty acid oxidation. We hypothesized that energy deprivation accounts for sepsis-related cardiac dysfunction. METHODS AND RESULTS Escherichia coli lipopolysaccharide (LPS) administered to C57BL/6 mice (wild type) induced cardiac dysfunction and reduced fatty acid oxidation and mRNA levels of peroxisome proliferator-activated receptor (PPAR)-α and its downstream targets within 6-8 hours. Transgenic mice in which cardiomyocyte-specific expression of PPARγ is driven by the α-myosin heavy chain promoter (αMHC-PPARγ) were protected from LPS-induced cardiac dysfunction. Despite a reduction in PPARα, fatty acid oxidation and associated genes were not decreased in hearts of LPS-treated αMHC-PPARγ mice. LPS treatment, however, continued to induce inflammation-related genes, such as interleukin-1α, interleukin-1β, interleukin-6, and tumor necrosis factor-α in hearts of αMHC-PPARγ mice. Treatment of wild-type mice with LPS and the PPARγ agonist, rosiglitazone, but not the PPARα agonist (WY-14643), increased fatty acid oxidation, prevented LPS-mediated reduction of mitochondria, and treated cardiac dysfunction, as well as it improved survival, despite continued increases in the expression of cardiac inflammatory markers. CONCLUSIONS Activation of PPARγ in LPS-treated mice prevented cardiac dysfunction and mortality, despite development of cardiac inflammation and PPARα downregulation.
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Affiliation(s)
- Konstantinos Drosatos
- Division of Preventive Medicine and Nutrition, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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Thiazolidinediones are acute, specific inhibitors of the mitochondrial pyruvate carrier. Proc Natl Acad Sci U S A 2013; 110:5422-7. [PMID: 23513224 DOI: 10.1073/pnas.1303360110] [Citation(s) in RCA: 220] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Facilitated pyruvate transport across the mitochondrial inner membrane is a critical step in carbohydrate, amino acid, and lipid metabolism. We report that clinically relevant concentrations of thiazolidinediones (TZDs), a widely used class of insulin sensitizers, acutely and specifically inhibit mitochondrial pyruvate carrier (MPC) activity in a variety of cell types. Respiratory inhibition was overcome with methyl pyruvate, localizing the effect to facilitated pyruvate transport, and knockdown of either paralog, MPC1 or MPC2, decreased the EC50 for respiratory inhibition by TZDs. Acute MPC inhibition significantly enhanced glucose uptake in human skeletal muscle myocytes after 2 h. These data (i) report that clinically used TZDs inhibit the MPC, (ii) validate that MPC1 and MPC2 are obligatory components of facilitated pyruvate transport in mammalian cells, (iii) indicate that the acute effect of TZDs may be related to insulin sensitization, and (iv) establish mitochondrial pyruvate uptake as a potential therapeutic target for diseases rooted in metabolic dysfunction.
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Jonkers RAM, van Loon LJC, Nicolay K, Prompers JJ. In vivo postprandial lipid partitioning in liver and skeletal muscle in prediabetic and diabetic rats. Diabetologia 2013; 56:618-26. [PMID: 23238787 PMCID: PMC3563947 DOI: 10.1007/s00125-012-2792-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 11/12/2012] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Insulin resistance and type 2 diabetes have been associated with ectopic lipid deposition. This study investigates the derangements in postprandial lipid handling in liver and skeletal muscle tissue at different stages during the pathogenesis of type 2 diabetes in a rat model. METHODS Four groups (n = 6) of male Zucker diabetic fatty rats were used for this study: prediabetic fa/fa rats and healthy fa/+ littermates at the age of 6 weeks, and diabetic fa/fa rats and healthy fa/+ littermates at the age of 12 weeks. In vivo (1)H-[(13)C] magnetic resonance spectroscopy measurements were performed in liver and tibialis anterior muscle at baseline and 4, 24 and 48 h after oral administration of 1.5 g [U-(13)C]algal lipid mixture per kilogram body weight. Total and (13)C-labelled intracellular lipid contents were determined from the magnetic resonance spectra. RESULTS In both prediabetic and diabetic rats, total lipid contents in muscle and liver were substantially higher than in healthy controls and this was accompanied by a 2.3-fold greater postprandial lipid uptake in the liver (p < 0.001). Interestingly, in prediabetic rats, skeletal muscle appeared to be protected from excess lipid uptake whereas after developing overt diabetes muscle lipid uptake was 3.4-fold higher than in controls (p < 0.05). Muscle lipid use was significantly lower in prediabetic and diabetic muscle, indicative of impairments in lipid oxidation. CONCLUSIONS/INTERPRETATION In vivo postprandial lipid handling is disturbed in both liver and skeletal muscle tissue in prediabetic and diabetic rats, but the uptake of dietary lipids in muscle is only increased after the development of overt diabetes.
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Affiliation(s)
- R. A. M. Jonkers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands
| | - L. J. C. van Loon
- NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Movement Sciences, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - K. Nicolay
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands
| | - J. J. Prompers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands
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Wang LY, Wang Y, Xu DS, Ruan KF, Feng Y, Wang S. MDG-1, a polysaccharide from Ophiopogon japonicus exerts hypoglycemic effects through the PI3K/Akt pathway in a diabetic KKAy mouse model. JOURNAL OF ETHNOPHARMACOLOGY 2012; 143:347-354. [PMID: 22776833 DOI: 10.1016/j.jep.2012.06.050] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 06/19/2012] [Accepted: 06/30/2012] [Indexed: 06/01/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Ophiopogon japonicus is a traditional Chinese medicine that might be helpful for the treatment of type 2 diabetes. Recent studies have confirmed its beneficial properties, but not the mechanism of action. AIM OF STUDY In this study, we examined the effects of a water-soluble β-d-fructan (MDG-1) from O. japonicus on type 2 diabetes through the PI3K/Akt pathway in a diabetic KKAy mouse model. MATERIALS AND METHODS MDG-1 was extracted from the tube root of O. japonicus and purified as described previously (Xu et al., 2005). The KKAy mice were gavaged once daily with either distilled water, MDG-1or rosiglitazonefor 8 weeks. Blood glucose levels were tested regularly for the fed and fasted mice. In order to evaluate the effect of MDG-1 on disease progression, the proteins of InsR/IRS-1/PI3K/Akt/GSK-3/Glut-4 were detected by Western blotting and serum TG, TC, HDL-C, LDL-C were also dertermined. RESULTS MDG-1 reduced the hyperglycemia, hyperinsulinemia and hyperlipidemia in the KKAy mice. The oral glucose tolerance test (OGTT) and the level of insulin in the serun showed that insulin resistance in KKAy mice was ameliorated after MDG-1 treated. After 8 weeks treatment with 300mg/kg MDG-1, the content of triglycerides (TG) and low density lipoprotein cholesterol (LDL-C) the serum decreased significantly. Meanwhile high density lipoprotein cholesterol (HDL-C) content increased notably. MDG-1 did not have any effect on total cholesterol (TC) content in the serum, whereas rosiglitazone significantly decreased the TC content. In addition, MDG-1 upregulates the phosphoinositide 3-kinase p85 subunit, Akt, insulin receptor (InsR), insulin receptor substrate-1 (IRS-1) and Glut-4 expression, but downregulates glycogen synthase kinase 3β expression. CONCLUSIONS These data indicate that MDG-1 has remarkable anti-diabetic activity through the InsR/IRS-1/PI3K/Akt/GSK-3/Glut-4 signaling pathway. We believe that MDG-1 is a promising anti-diabetic compound that will be helpful for the treatment of T2DM.
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Affiliation(s)
- Ling-Yi Wang
- Department of TCM, Shanghai University of Traditional Chinese Medicine, Pudong, Shanghai 201203, People's Republic of China
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Scherp P, Putluri N, LeBlanc GJ, Wang ZQ, Zhang XH, Yu Y, Ribnicky D, Cefalu WT, Kheterpal I. Proteomic analysis reveals cellular pathways regulating carbohydrate metabolism that are modulated in primary human skeletal muscle culture due to treatment with bioactives from Artemisia dracunculus L. J Proteomics 2012; 75:3199-210. [PMID: 22480907 DOI: 10.1016/j.jprot.2012.03.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 03/14/2012] [Accepted: 03/16/2012] [Indexed: 12/25/2022]
Abstract
Insulin resistance is a major pathophysiologic abnormality that characterizes metabolic syndrome and type 2 diabetes. A well characterized ethanolic extract of Artemisia dracunculus L., termed PMI 5011, has been shown to improve insulin action in vitro and in vivo, but the cellular mechanisms remain elusive. Using differential proteomics, we have studied mechanisms by which PMI 5011 enhances insulin action in primary human skeletal muscle culture obtained by biopsy from obese, insulin-resistant individuals. Using iTRAQ™ labeling and LC-MS/MS, we have identified over 200 differentially regulated proteins due to treatment with PMI 5011 and insulin stimulation. Bioinformatics analyses determined that several metabolic pathways related to glycolysis, glucose transport and cell signaling were highly represented and differentially regulated in the presence of PMI 5011 indicating that this extract affects several pathways modulating carbohydrate metabolism, including translocation of GLUT4 to the plasma membrane. These findings provide a molecular mechanism by which a botanical extract improves insulin stimulated glucose uptake, transport and metabolism at the cellular level resulting in enhanced whole body insulin sensitivity.
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Affiliation(s)
- Peter Scherp
- Protein Structural Biology, Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA 70808, USA
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Szendroedi J, Phielix E, Roden M. The role of mitochondria in insulin resistance and type 2 diabetes mellitus. Nat Rev Endocrinol 2011; 8:92-103. [PMID: 21912398 DOI: 10.1038/nrendo.2011.138] [Citation(s) in RCA: 419] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Type 2 diabetes mellitus (T2DM) has been related to alterations of oxidative metabolism in insulin-responsive tissues. Overt T2DM can present with acquired or inherited reductions of mitochondrial oxidative phosphorylation capacity, submaximal ADP-stimulated oxidative phosphorylation and plasticity of mitochondria and/or lower mitochondrial content in skeletal muscle cells and potentially also in hepatocytes. Acquired insulin resistance is associated with reduced insulin-stimulated mitochondrial activity as the result of blunted mitochondrial plasticity. Hereditary insulin resistance is frequently associated with reduced mitochondrial activity at rest, probably due to diminished mitochondrial content. Lifestyle and pharmacological interventions can enhance the capacity for oxidative phosphorylation and mitochondrial content and improve insulin resistance in some (pre)diabetic cases. Various mitochondrial features can be abnormal but are not necessarily responsible for all forms of insulin resistance. Nevertheless, mitochondrial abnormalities might accelerate progression of insulin resistance and subsequent organ dysfunction via increased production of reactive oxygen species. This Review discusses the association between mitochondrial function and insulin sensitivity in various tissues, such as skeletal muscle, liver and heart, with a main focus on studies in humans, and addresses the effects of therapeutic strategies that affect mitochondrial function and insulin sensitivity.
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Affiliation(s)
- Julia Szendroedi
- Institute for Clinical Diabetology, German Diabetes Center, D-40225 Düsseldorf, Germany
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Krämer DK, Bouzakri K, Holmqvist O, Al-Khalili L, Krook A. Effect of serum replacement with plysate on cell growth and metabolismin primary cultures of human skeletal muscle. Cytotechnology 2011; 48:89-95. [PMID: 19003035 DOI: 10.1007/s10616-005-4074-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Accepted: 10/13/2005] [Indexed: 12/25/2022] Open
Abstract
Cell- and tissue culture methodology form an important base for biological, biochemical and biomedical research. Most cell culture techniques require the use of animal sera for the successful propagation of cells. However, the varying composition between batches has fuelled the need for alternatives. In the case of serum derived from animal foetuses, ethical concerns have also been raised. Here we compare the use of a platelet derived lysate (Plysate), which is currently under development as a serum substitute, in the culturing of primary human muscle cells to foetal bovine serum (FBS). In cells cultured with Plysate, differentiation into myotubes, glucose-uptake, phosphatidylinositol 3-kinase (PI3K) activity and expression and phosphorylation of ERK1/2 MAPK and PKB/Akt was impaired. Thus for primary human skeletal muscle Plysate is a sub-optimal substitute for FBS.
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Affiliation(s)
- David K Krämer
- Department of Surgical Science, Karolinska Institutet, S-171 77, Stockholm, Sweden
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de las Fuentes L, de Simone G, Arnett DK, Dávila-Román VG. Molecular determinants of the cardiometabolic phenotype. Endocr Metab Immune Disord Drug Targets 2011; 10:109-23. [PMID: 20384572 DOI: 10.2174/187153010791213119] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 04/04/2010] [Indexed: 12/25/2022]
Abstract
The metabolic syndrome represents a clustering of risk factors that has been shown to predict adverse cardiovascular outcomes. Although the precise mechanisms contributing to the cardiometabolic syndrome (CMS) remain poorly defined, accumulating evidence identifies two intersecting candidate pathways responsible for inflammation and energy homeostasis in the pathophysiology that underlie cardiometabolic traits. Although currently no pharmacologic interventions specifically target CMS, future drug development efforts should attempt to capitalize on molecular nodes at the intersections of these pathways in the CMS.
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Affiliation(s)
- Lisa de las Fuentes
- Cardiovascular Imaging and Clinical Research Core Laboratory, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Kurundkar SB, Sachan N, Kodam KM, Kulkarni VM, Bodhankar SL, Ghole VS. Effect of a novel biphenyl compound, VMNS2e on ob/ob mice. Eur J Pharmacol 2011; 650:472-8. [PMID: 20950599 DOI: 10.1016/j.ejphar.2010.09.067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 09/17/2010] [Accepted: 09/23/2010] [Indexed: 12/25/2022]
Abstract
VMNS2e is a novel biphenyl compound, which in previous studies had showed most favourable interactions with the active site of protein tyrosine phosphatase 1B (PTP1B). The effect of acute and chronic treatment of VMNS2e (30mg/kg) was investigated in ob/ob mice. Plasma glucose was measured after acute administration of VMNS2e (30mg/kg) in both lean and ob/ob mice. In the chronic study, VMNS2e (30mg/kg) was given orally, once daily for 60days. Metformin (300mg/kg) was taken as standard therapy. Body weight, food intake and blood glucose was measured weekly while glycosylated hemoglobin A(1c) (HbA(1c)), insulin, triglyceride, total cholesterol, low density lipoprotein (LDL), fructosamine, non esterified fatty acid and organ weight were estimated after the completion of treatment period. Oral glucose tolerance test was performed on the last day of treatment. Liver and epididymal fat weights were taken. Acute dose of VMNS2e elicited an anti hyperglycemic effect. It reduced blood glucose by 14% (0.5h) and 35.6% (6h). Chronic VMNS2e treatment improved glucose tolerance by 25.3%. It decreased blood glucose levels. Hyperinsulinemia was reduced (19.6%). VMNS2e treatment had no significant effect on body weight and food consumption. VMNS2e treatment exhibited significant reduction (28.2%) in HbA(1c), plasma triglyceride (49%), LDL (24%) and fructosamine (13%) levels. VMNS2e treatment did not alter total cholesterol and non esterified fatty acid levels. Epididymal fat/body weight ratio was reduced (26.3%). VMNS2e exhibited both acute and chronic anti hyperglycemic effect, insulin sensitivity along with improvement in various lipid parameters and glycemic control.
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Affiliation(s)
- Sucheta B Kurundkar
- Division of Biochemistry, Department of Chemistry, University of Pune, Pune, India.
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Amin RH, Mathews ST, Alli A, Leff T. Endogenously produced adiponectin protects cardiomyocytes from hypertrophy by a PPARgamma-dependent autocrine mechanism. Am J Physiol Heart Circ Physiol 2010; 299:H690-8. [PMID: 20622112 DOI: 10.1152/ajpheart.01032.2009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In experimental animal and cell culture models, activation of peroxisome proliferator-activated receptor (PPAR) gamma in heart has been shown to have beneficial effects on cardiac function and cardiomyocyte physiology. The goal of this study was to identify the signaling pathway by which PPARgamma activation protects cardiomyocytes from the deleterious effects of hypertrophic stimuli. In primary cardiomyocyte cultures, we found that genetic or pharmacological activation of PPARgamma protected cells from cardiac hypertrophy induced by alpha-adrenergic stimulation. Examination of gene expression in these cells revealed a surprising increase in the expression of adiponectin in cardiomyocytes and secretion of the high-molecular-weight form of the hormone into media. Using RNAi to block PPARgamma-induced adiponectin production or adiponectin receptor gene expression, we found that the PPARgamma-mediated anti-hypertrophic effect required cardiomyocyte-produced adiponectin, as well as an intact adiponectin signaling pathway. Furthermore, mice expressing constitutive-active PPARgamma and cardiomyocyte specific adiponectin expression were protected from high-fat diet-induced cardiac hypertrophy and remodeling. These findings demonstrate that functional adiponectin hormone can be produced from the heart and raise the possibility that beneficial effects of PPARgamma activation in heart could be due in part to local production of adiponectin that acts on cardiomyocytes in an autocrine manner.
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Affiliation(s)
- Rajesh H Amin
- Department of Pathology, Center for Integrative Metabolic & Endocrine Research, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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Skrobuk P, Kuoppamaa H, Hiukka A, Koistinen HA. Acute exposure to rosiglitazone does not affect glucose transport in intact human skeletal muscle. Metabolism 2010; 59:224-30. [PMID: 19765783 DOI: 10.1016/j.metabol.2009.07.016] [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] [Received: 05/27/2009] [Revised: 07/10/2009] [Accepted: 07/16/2009] [Indexed: 12/25/2022]
Abstract
Thiazolidinediones (TZDs) such as rosiglitazone are widely used as antidiabetic drugs. Animal studies suggest that TZDs may have direct metabolic actions in skeletal muscle. Here, we examined if acute exposure to rosiglitazone stimulates glucose transport rate and affects proximal insulin signaling in isolated skeletal muscle strips from nondiabetic men. Open muscle biopsies were obtained from musculus vastus lateralis from 15 nondiabetic men (50 +/- 3 years old, 26.9 +/- 1.1 kg/m(2)). Skeletal muscle strips were isolated and exposed to rosiglitazone (1 or 10 micromol/L), 5-aminoimidazole-4-carboxamide 1-beta-D-ribonucleoside (1 mmol/L), insulin (120 nmol/L), or a combination of insulin (120 nmol/L) and rosiglitazone (10 micromol/L) in vitro for 1 hour. Glucose transport was analyzed by accumulation of intracellular 3-O-methyl [(3)H] glucose; phosphorylation of Akt-Ser(473) and Akt-Thr(308) and phosphorylation of acetyl coenzyme A carboxylase beta were determined using phosphospecific antibodies. 5-Aminoimidazole-4-carboxamide 1-beta-d-ribonucleoside and insulin increased glucose transport rate 1.5-fold (P < .05) and 1.7-fold (P < .01) in isolated muscle strips, respectively. Exposure to rosiglitazone transiently increased phosphorylation of acetyl coenzyme A carboxylase beta, with a maximum effect at 15 minutes and return to baseline at 60 minutes. However, rosiglitazone did not affect basal or insulin-stimulated glucose transport rate, or phosphorylation of Akt-Ser(473) or Akt-Thr(308) in isolated muscle strips. In conclusion, acute exposure to rosiglitazone does not affect glucose transport in human skeletal muscle.
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Affiliation(s)
- Paulina Skrobuk
- Division of Cardiology, Department of Medicine, Helsinki University Central Hospital, 00290 Helsinki, Finland
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Pagel-Langenickel I, Bao J, Pang L, Sack MN. The role of mitochondria in the pathophysiology of skeletal muscle insulin resistance. Endocr Rev 2010; 31:25-51. [PMID: 19861693 PMCID: PMC2852205 DOI: 10.1210/er.2009-0003] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 08/27/2009] [Indexed: 12/18/2022]
Abstract
Multiple organs contribute to the development of peripheral insulin resistance, with the major contributors being skeletal muscle, liver, and adipose tissue. Because insulin resistance usually precedes the development of type 2 diabetes mellitus (T2DM) by many years, understanding the pathophysiology of insulin resistance should enable development of therapeutic strategies to prevent disease progression. Some subjects with mitochondrial genomic variants/defects and a subset of lean individuals with hereditary predisposition to T2DM exhibit skeletal muscle mitochondrial dysfunction early in the course of insulin resistance. In contrast, in the majority of subjects with T2DM the plurality of evidence implicates skeletal muscle mitochondrial dysfunction as a consequence of perturbations associated with T2DM, and these mitochondrial deficits then contribute to subsequent disease progression. We review the affirmative and contrarian data regarding skeletal muscle mitochondrial biology in the pathogenesis of insulin resistance and explore potential therapeutic options to intrinsically modulate mitochondria as a strategy to combat insulin resistance. Furthermore, an overview of restricted molecular manipulations of skeletal muscle metabolic and mitochondrial biology offers insight into the mitochondrial role in metabolic substrate partitioning and in promoting innate adaptive and maladaptive responses that collectively regulate peripheral insulin sensitivity. We conclude that skeletal muscle mitochondrial dysfunction is not generally a major initiator of the pathophysiology of insulin resistance, although its dysfunction is integral to this pathophysiology and it remains an intriguing target to reverse/delay the progressive perturbations synonymous with T2DM.
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Affiliation(s)
- Ines Pagel-Langenickel
- Translational Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Drive, Bethesda, Maryland 20892-1454, USA
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Godoy-Matos AF, Bahia LR, Domingues RC, Tambascia M, Geloneze B, Kraemer-Aguiar LG, Bouskela E. Rosiglitazone decreases intra- to extramyocellular fat ratio in obese non-diabetic adults with metabolic syndrome. Diabet Med 2010; 27:23-9. [PMID: 20121885 DOI: 10.1111/j.1464-5491.2009.02868.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Insulin resistance is intrinsically related to intramyocellular (IMCL) rather than extramyocellular (EMCL) triglyceride content. Conflicting results have been reported on the ability of insulin sensitizer agents, such as thiazolidinediones, to modify muscle fat distribution. The aim of this study was to investigate the role of rosiglitazone on muscle fat compartment distribution in an adult population of obese non-diabetic metabolic syndrome patients. PATIENTS AND METHODS Fifteen obese, non-diabetic, metabolic syndrome patients were studied by means of proton nuclear magnetic resonance ((1)H-NMR) spectroscopy before and after treatment with rosiglitazone 8 mg/day for 6 months. Anthropometrical and metabolic variables were assessed. RESULTS After rosiglitazone, body weight and hip circumference increased [100.9 (91.12-138.7) vs. 107.0 (79.6-142.8) kg and 118 (107-126) vs. 122 (110-131) cm]; while waist-hip ratio (WHR) decreased from 0.93 (0.87-1.00) to 0.89 (0.82-0.97) (P < 0.001 for all). Additionally, fasting plasma glucose, insulin and homeostatis model assessment of insulin resistance (HOMA-IR) significantly decreased while adiponectin increased over threefold [9.7 (3.7-17.7) vs. 38.0 (19.3-42.4) microg/ml] without any changes in resistin. Finally, the IMCL did not change [267.54 (213.94-297.94) vs. 305.75 (230.80-424.75) arbitrary units (AU), P = 0.15] while the EMCL increased [275.53 (210.39-436.66) vs. 411.39 (279.92-556.59) AU; P < 0.01] therefore decreasing the IMCL-to-EMCL (IMCL/EMCL) ratio [1.07 (0.78-1.23) vs. 0.71 (0.53-0.96); P < 0.01]. CONCLUSION Rosiglitazone treatment increased body weight and hip circumference and decreased WHR. More importantly, it decreased the IMCL/EMCL ratio by increasing the EMCL without any significant change on the IMCL.
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Affiliation(s)
- A F Godoy-Matos
- State Institute of Diabetes and Endocrinology, IEDE, Rio de Janeiro, Brazil
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Wu HS, Zhu DF, Zhou CX, Feng CR, Lou YJ, Yang B, He QJ. Insulin sensitizing activity of ethyl acetate fraction of Acorus calamus L. in vitro and in vivo. JOURNAL OF ETHNOPHARMACOLOGY 2009; 123:288-292. [PMID: 19429374 DOI: 10.1016/j.jep.2009.03.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 02/24/2009] [Accepted: 03/07/2009] [Indexed: 05/27/2023]
Abstract
UNLABELLED Acorus calamus L. (AC), family Araceae, have been used in the Indian and Chinese systems of medicine for hundreds of years. The radix of AC is widely used in the therapy of diabetes in traditional folk medicine of America and Indonesia. AIM OF THE STUDY To investigate the insulin sensitizing activity and antidiabetic effects of the ethyl acetate fraction of AC (ACE). MATERIALS AND METHODS Glucose consumption mediated by insulin was detected in L6 rat skeletal muscle cells. Diabetes and its complications related indexes were monitored after orally administrating to genetically obese diabetic C57BL/Ks db/db mice daily for 3 weeks. RESULTS ACE (12.5 and 25 microg/ml) increased glucose consumption mediated by insulin in L6 cells (p<0.05 and p<0.01). In db/db mice, ACE (100 mg/kg) significantly reduced serum glucose, triglyceride, reinforce the decrease of total cholesterol caused by rosiglitazone (at least p<0.05), and markedly reduced free fatty acid (FFA) levels and increased adiponectin levels (p<0.01 and p<0.05) as rosiglitazone did (p<0.05 and p<0.001). Serum insulin was decreased but not significantly. In addition, ACE decreased the intake of food and water, and did not increase body weight gain whereas rosiglitazone did. CONCLUSIONS Owing to the ability of insulin sensitizing, ACE has the potential to be useful for the treatment of diabetes and cardiovascular complications without body weight gain.
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Affiliation(s)
- Hao-Shu Wu
- Institute of Pharmacology & Toxicology and Biochemical Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, 388 Yu-hang-tang Road, Hangzhou, China.
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Hallén S, Clapham JC. Cell based in vitro and ex vivo models in metabolic disease drug discovery: nice to have or critical path? Expert Opin Drug Discov 2009; 4:417-28. [PMID: 23485042 DOI: 10.1517/17460440902821640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND The use of cellular models as tools in drug discovery is almost universal. However, in disease areas such as metabolic diseases, are they relevant to the process and do they add value? OBJECTIVE In this article, we explore the variety of cellular models now used in drug discovery in metabolic diseases as revealed by publication. We have tried to make some connections between drug phenotypes in these models with clinical parallels. We also ask the question as to whether such models add value in the drug discovery process. This overview is not about recombinant cell systems used in target-based screening; rather, we focus on in vitro, including ex vivo, models as physiological systems in drug discovery in obesity and diabetes. CONCLUSION In terms of building target confidence, in vitro models are often the only mechanistic link to human systems early in a projects life. Many of the current targets in metabolic diseases in the early discovery phase are not yet clinically supported, let alone validated. In this respect, therefore, in vitro models warrant a place in the critical path in early discovery. In terms of any predictive role for decision-making today, this is much more difficult and is more likely pushed to a supporting role as part of a wider package. However, there is a rapid rate of advancement in this field and future developments hold much promise.
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Affiliation(s)
- Stefan Hallén
- Departments of Bioscience, AstraZeneca R&D Mölndal, Sweden +46 31 7064339 ; +46 31 7763700 ;
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Takamura T, Misu H, Matsuzawa-Nagata N, Sakurai M, Ota T, Shimizu A, Kurita S, Takeshita Y, Ando H, Honda M, Kaneko S. Obesity upregulates genes involved in oxidative phosphorylation in livers of diabetic patients. Obesity (Silver Spring) 2008; 16:2601-9. [PMID: 18846047 DOI: 10.1038/oby.2008.419] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Obesity is a major cause of insulin resistance and contributes to the development of type 2 diabetes. The altered expression of genes involved in mitochondrial oxidative phosphorylation (OXPHOS) has been regarded as a key change in insulin-sensitive organs of patients with type 2 diabetes. This study explores possible molecular signatures of obesity and examines the clinical significance of OXPHOS gene expression in the livers of patients with type 2 diabetes. We analyzed gene expression in the livers of 21 patients with type 2 diabetes (10 obese and 11 nonobese patients; age, 53.0 +/- 2.1 years; BMI, 24.4 +/- 0.9 kg/m(2); fasting plasma glucose, 143.0 +/- 10.6 mg/dl) using a DNA chip. We screened 535 human pathways and extracted those metabolic pathways significantly altered by obesity. Genes involved in the OXPHOS pathway, together with glucose and lipid metabolism pathways, were coordinately upregulated in the liver in association with obesity. The mean centroid of OXPHOS gene expression was significantly correlated with insulin resistance indices and the hepatic expression of genes involved in gluconeogenesis, reactive oxygen species (ROS) generation, and transcriptional factors and nuclear co-activators associated with energy homeostasis. In conclusion, obesity may affect the pathophysiology of type 2 diabetes by upregulating genes involved in OXPHOS in association with insulin resistance markers and the expression of genes involved in hepatic gluconeogenesis and ROS generation.
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Affiliation(s)
- Toshinari Takamura
- Department of Disease Control and Homeostasis, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
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Norris AW, Hirshman MF, Yao J, Jessen N, Musi N, Chen L, Sivitz WI, Goodyear LJ, Kahn CR. Endogenous peroxisome proliferator-activated receptor-gamma augments fatty acid uptake in oxidative muscle. Endocrinology 2008; 149:5374-83. [PMID: 18653710 PMCID: PMC2584586 DOI: 10.1210/en.2008-0100] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In the setting of insulin resistance, agonists of peroxisome proliferator-activated receptor (PPAR)-gamma restore insulin action in muscle and promote lipid redistribution. Mice with muscle-specific knockout of PPARgamma (MuPPARgammaKO) develop excess adiposity, despite reduced food intake and normal glucose disposal in muscle. To understand the relation between muscle PPARgamma and lipid accumulation, we studied the fuel energetics of MuPPARgammaKO mice. Compared with controls, MuPPARgammaKO mice exhibited significantly increased ambulatory activity, muscle mitochondrial uncoupling, and respiratory quotient. Fitting with this latter finding, MuPPARgammaKO animals compared with control siblings exhibited a 25% reduction in the uptake of the fatty acid tracer 2-bromo-palmitate (P < 0.05) and a 13% increase in serum nonesterified fatty acids (P = 0.05). These abnormalities were associated with no change in AMP kinase (AMPK) phosphorylation, AMPK activity, or phosphorylation of acetyl-CoA carboxylase in muscle and occurred despite increased expression of fatty acid transport protein 1. Palmitate oxidation was not significantly altered in MuPPARgammaKO mice despite the increased expression of several genes promoting lipid oxidation. These data demonstrate that PPARgamma, even in the absence of exogenous activators, is required for normal rates of fatty acid uptake in oxidative skeletal muscle via mechanisms independent of AMPK and fatty acid transport protein 1. Thus, when PPARgamma activity in muscle is absent or reduced, there will be decreased fatty acid disposal leading to diminished energy utilization and ultimately adiposity.
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Affiliation(s)
- Andrew W Norris
- Department of Pediatrics, University of Iowa, Iowa City, Iowa 52242, USA.
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Wang ZQ, Ribnicky D, Zhang XH, Raskin I, Yu Y, Cefalu WT. Bioactives of Artemisia dracunculus L enhance cellular insulin signaling in primary human skeletal muscle culture. Metabolism 2008; 57:S58-64. [PMID: 18555856 PMCID: PMC2981033 DOI: 10.1016/j.metabol.2008.04.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
An alcoholic extract of Artemisia dracunculus L (PMI 5011) has been shown to decrease glucose and improve insulin levels in animal models, suggesting an ability to enhance insulin sensitivity. We sought to assess the cellular mechanism by which this botanical affects carbohydrate metabolism in primary human skeletal muscle culture. We measured basal and insulin-stimulated glucose uptake, glycogen accumulation, phosphoinositide 3 (PI-3) kinase activity, and Akt phosphorylation in primary skeletal muscle culture from subjects with type 2 diabetes mellitus incubated with or without various concentrations of PMI 5011. We also analyzed the abundance of insulin receptor signaling proteins, for example, IRS-1, IRS-2, and PI-3 kinase. Glucose uptake was significantly increased in the presence of increasing concentrations of PMI 5011. In addition, glycogen accumulation, observed to be decreased with increasing free fatty acid levels, was partially restored with PMI 5011. PMI 5011 treatment did not appear to significantly affect protein abundance for IRS-1, IRS-2, PI-3 kinase, Akt, insulin receptor, or Glut-4. However, PMI 5011 significantly decreased levels of a specific protein tyrosine phosphatase, that is, PTP1B. Time course studies confirmed that protein abundance of PTP1B decreases in the presence of PMI 5011. The cellular mechanism of action to explain the effects by which an alcoholic extract of A dracunculus L improves carbohydrate metabolism on a clinical level may be secondary to enhancing insulin receptor signaling and modulating levels of a specific protein tyrosine phosphatase, that is, PTP1B.
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Affiliation(s)
- Zhong Q. Wang
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA
| | - David Ribnicky
- Biotech Center, Rutgers University, New Brunswick, NJ 08901, USA
| | - Xian H. Zhang
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA
| | - Ilya Raskin
- Biotech Center, Rutgers University, New Brunswick, NJ 08901, USA
| | - Yongmei Yu
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA
| | - William T. Cefalu
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA
- Corresponding author. Tel.: +1 225 763 2654; fax: +1 225 763 3030. (W.T. Cefalu)
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Abstract
Insulin resistance is a characteristic feature of type 2 diabetes mellitus, obesity, and the metabolic syndrome. Increased intracellular fat content in skeletal muscle and liver associated with insulin resistance has led to the hypothesis that a mitochondrial defect in substrate oxidation exists in disorders of insulin resistance. In vivo measurements of metabolic fluxes through the tricarboxylic acid and oxidative phosphorylation with magnetic resonance spectroscopy have demonstrated multiple defects in mitochondrial function in skeletal muscle. A decrease in mitochondrial density and mitochondrial copy number has been reported in insulin-resistant individuals. However, these findings have not been a consistent observation in all studies. Similarly, an intrinsic functional defect in mitochondrial adenosine triphosphate production synthesis has been reported in some but not all studies. This review summarizes evidence that implicates a defect in mitochondrial oxidative phosphorylation and its relationship to insulin resistance in common metabolic diseases characterized by impaired insulin action.
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Affiliation(s)
- Muhammad A Abdul-Ghani
- Diabetes Division, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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Bays HE, González-Campoy JM, Bray GA, Kitabchi AE, Bergman DA, Schorr AB, Rodbard HW, Henry RR. Pathogenic potential of adipose tissue and metabolic consequences of adipocyte hypertrophy and increased visceral adiposity. Expert Rev Cardiovasc Ther 2008; 6:343-68. [PMID: 18327995 DOI: 10.1586/14779072.6.3.343] [Citation(s) in RCA: 334] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
When caloric intake exceeds caloric expenditure, the positive caloric balance and storage of energy in adipose tissue often causes adipocyte hypertrophy and visceral adipose tissue accumulation. These pathogenic anatomic abnormalities may incite metabolic and immune responses that promote Type 2 diabetes mellitus, hypertension and dyslipidemia. These are the most common metabolic diseases managed by clinicians and are all major cardiovascular disease risk factors. 'Disease' is traditionally characterized as anatomic and physiologic abnormalities of an organ or organ system that contributes to adverse health consequences. Using this definition, pathogenic adipose tissue is no less a disease than diseases of other body organs. This review describes the consequences of pathogenic fat cell hypertrophy and visceral adiposity, emphasizing the mechanistic contributions of genetic and environmental predispositions, adipogenesis, fat storage, free fatty acid metabolism, adipocyte factors and inflammation. Appreciating the full pathogenic potential of adipose tissue requires an integrated perspective, recognizing the importance of 'cross-talk' and interactions between adipose tissue and other body systems. Thus, the adverse metabolic consequences that accompany fat cell hypertrophy and visceral adiposity are best viewed as a pathologic partnership between the pathogenic potential adipose tissue and the inherited or acquired limitations and/or impairments of other body organs. A better understanding of the physiological and pathological interplay of pathogenic adipose tissue with other organs and organ systems may assist in developing better strategies in treating metabolic disease and reducing cardiovascular disease risk.
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Affiliation(s)
- Harold E Bays
- L-MARC Research Center, 3288 Illinois Avenue, Louisville, KY 40213, USA.
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Sonobe C, Nakamura M, Wada M, Nakashima K. HPLC Determination of Medium-Chain Fatty Acids in Human Plasma and Their Relationship with Homocysteine Concentration. BUNSEKI KAGAKU 2008. [DOI: 10.2116/bunsekikagaku.57.631] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Chikako Sonobe
- Department of Clinical Pharmacy, Graduate School of Biomedical Sciences, Nagasaki University
| | - Mayumi Nakamura
- Department of Clinical Pharmacy, Graduate School of Biomedical Sciences, Nagasaki University
| | - Mitsuhiro Wada
- Department of Clinical Pharmacy, Graduate School of Biomedical Sciences, Nagasaki University
| | - Kenichiro Nakashima
- Department of Clinical Pharmacy, Graduate School of Biomedical Sciences, Nagasaki University
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Nadeau KJ, Ehlers LB, Aguirre LE, Reusch JEB, Draznin B. Discordance between intramuscular triglyceride and insulin sensitivity in skeletal muscle of Zucker diabetic rats after treatment with fenofibrate and rosiglitazone. Diabetes Obes Metab 2007; 9:714-23. [PMID: 17697064 DOI: 10.1111/j.1463-1326.2006.00696.x] [Citation(s) in RCA: 15] [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: 12/25/2022]
Abstract
AIM Intramyocellular triglyceride (IMTG) correlates with insulin resistance, but there is no clear causal relationship. Insulin resistance and associated hyperinsulinaemia may increase IMTG, via the insulin-regulated transcription factor, sterol regulatory element-binding protein 1 (SREBP-1). PPAR agonists may also affect IMTG via changes in insulin sensitivity, SREBP-1 or other factors. METHODS We examined skeletal muscle IMTG and SREBP-1 expression, and metabolic parameters in Zucker diabetic fatty rats (ZDF) after 25 weeks of PPAR-gamma or PPAR-alpha administration. RESULTS Compared with Zucker lean rats (ZL), untreated ZDF had significantly higher weights, serum glucose, insulin, free fatty acids, total cholesterol and triglycerides. IMTG and SREBP-1c messenger RNA (mRNA) were also higher in untreated ZDF; both were decreased by fenofibrate (FF). Rosiglitazone (Rosi), despite marked improvement in glycaemia, hyperinsulinaemia and hyperlipidaemia, failed to affect SREBP-1 expression, and increased body weight and IMTG. Rosi/FF combination caused less weight gain and no IMTG increase, despite metabolic effects similar to Rosi alone. CONCLUSIONS IMTG and SREBP-1c mRNA are high in the ZDF. FF and Rosi both improved insulin sensitivity but had opposite effects on IMTG. Thus, there was a clear discordance between insulin sensitivity and IMTG with PPAR agonists, indicating that IMTG and insulin sensitivity do not share a simple relationship.
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Affiliation(s)
- K J Nadeau
- Division of Pediatric Endocrinology, Department of Pediatrics, University of Colorado Health Sciences Center, Denver, CO, USA.
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Berggren JR, Tanner CJ, Houmard JA. Primary cell cultures in the study of human muscle metabolism. Exerc Sport Sci Rev 2007; 35:56-61. [PMID: 17417051 DOI: 10.1249/jes.0b013e31803eae63] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Skeletal muscle plays an important role in whole-body metabolism. Some research has used cell cultures raised from human biopsy tissue to study mechanisms that regulate skeletal muscle metabolism. The purpose of the current paper is to provide evidence indicating the efficacy of primary human skeletal muscle cell cultures as a tool to study substrate regulation and control in human tissue.
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Affiliation(s)
- Jason R Berggren
- Human Performance Laboratory and Department of Exercise and Sport Science, East Carolina University, Greenville, NC 27858, USA
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Mensink M, Hesselink MKC, Russell AP, Schaart G, Sels JP, Schrauwen P. Improved skeletal muscle oxidative enzyme activity and restoration of PGC-1α and PPARβ/δ gene expression upon rosiglitazone treatment in obese patients with type 2 diabetes mellitus. Int J Obes (Lond) 2007; 31:1302-10. [PMID: 17310221 DOI: 10.1038/sj.ijo.0803567] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE To examine whether rosiglitazone alters gene expression of some key genes involved in mitochondrial biogenesis and oxidative capacity in skeletal muscle of type 2 diabetic patients, and whether this is associated with alterations in skeletal muscle oxidative capacity and lipid content. DESIGN measured in muscle biopsies obtained from diabetic patients, before and after 8 weeks of rosiglitazone treatment, and matched controls. Furthermore, whole-body insulin sensitivity and substrate utilization were assessed. SUBJECTS Ten obese type 2 diabetic patients and 10 obese normoglycemic controls matched for age and BMI. METHODS Gene expression and mitochondrial protein content of complexes I-V of the respiratory chain were measured by quantitative polymerase chain reaction and Western blotting, respectively. Histochemical staining was used to quantify lipid accumulation and complex II succinate dehydrogenase (SDH) activity. Insulin sensitivity and substrate utilization were measured during a hyperinsulinemic-euglycemic clamp with indirect calorimetry. RESULTS Skeletal-muscle mRNA of PGC-1 alpha and PPAR beta/delta--but not of other genes involved in glucose, fat and oxidative metabolism--was significantly lower in diabetic patients (P<0.01). Rosiglitazone significantly increased PGC-1 alpha ( approximately 2.2-fold, P<0.01) and PPAR beta/delta ( approximately 2.6-fold, P<0.01), in parallel with an increase in insulin sensitivity, SDH activity and metabolic flexibility (P<0.01). Surprisingly, none of the measured mitochondrial proteins was reduced in type 2 diabetic patients, nor affected by rosiglitazone treatment. No alterations were seen in muscular fat accumulation upon treatment. CONCLUSION These results suggest that the insulin-sensitizing effect of rosiglitazone may involve an effect on muscular oxidative capacity, via PGC-1 alpha and PPAR beta/delta, independent of mitochondrial protein content and/or changes in intramyocellular lipid.
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Affiliation(s)
- M Mensink
- Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, Maastricht, The Netherlands.
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Hu X, Feng Y, Shen Y, Zhao XF, Yu JH, Yang YS, Leng Y. Antidiabetic effect of a novel non-thiazolidinedione PPAR gamma/alpha agonist on ob/ob mice. Acta Pharmacol Sin 2006; 27:1346-52. [PMID: 17007742 DOI: 10.1111/j.1745-7254.2006.00427.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
AIM To study whether T33, a new synthesized non-thiazolidinedione (TZD) peroxisome proliferator-activated receptor (PPAR) gamma/alpha dual agonist has an antidiabetic effect on ob/ob mice. METHODS Ob/ob mice were treated with 4 mg/kg or 8 mg/kg T33 by gavage for 20 d. Blood glucose levels were measured regularly. An oral glucose tolerance test (OGTT) and an insulin tolerance test (ITT) were preformed on d 8 and d 12, respectively. The levels of insulin, triglyceride and free fatty acid (FFA) in the serum were measured at the end of administration. The intramuscular and liver triglyceride content was also determined. RESULTS T33 reduced the hyperglycemia, hyperinsulinemia and hyperlipidemia of the ob/ob mice. The OGTT and ITT showed that the insulin resistance state of the ob/ob mice was obviously ameliorated after T33 treatment. After 20 d treatment with 8 mg/kg T33, the triglyceride content in the gastrocnemius muscle decreased significantly. T33 did not have any effect on triglyceride content in the liver, whereas rosiglitazone significantly increased the hepatocyte lipid deposition. CONCLUSION The PPARgamma/alpha dual agonist T33 has antidiabetic and insulin-sensitizing effects in ob/ob mice. It has the potential to be a new therapeutic candidate for the treatment of type 2 diabetes.
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Affiliation(s)
- Xi Hu
- Shanghai Institute of Materia Medica, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China
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45
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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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46
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Bandyopadhyay GK, Yu JG, Ofrecio J, Olefsky JM. Increased malonyl-CoA levels in muscle from obese and type 2 diabetic subjects lead to decreased fatty acid oxidation and increased lipogenesis; thiazolidinedione treatment reverses these defects. Diabetes 2006; 55:2277-85. [PMID: 16873691 DOI: 10.2337/db06-0062] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Increased accumulation of fatty acids and their derivatives can impair insulin-stimulated glucose disposal by skeletal muscle. To characterize the nature of the defects in lipid metabolism and to evaluate the effects of thiazolidinedione treatment, we analyzed the levels of triacylglycerol, long-chain fatty acyl-coA, malonyl-CoA, fatty acid oxidation, AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), malonyl-CoA decarboxylase, and fatty acid transport proteins in muscle biopsies from nondiabetic lean, obese, and type 2 subjects before and after an euglycemic-hyperinsulinemic clamp as well as pre-and post-3-month rosiglitazone treatment. We observed that low AMPK and high ACC activities resulted in elevation of malonyl-CoA levels and lower fatty acid oxidation rates. These conditions, along with the basal higher expression levels of fatty acid transporters, led accumulation of long-chain fatty acyl-coA and triacylglycerol in insulin-resistant muscle. During the insulin infusion, muscle fatty acid oxidation was reduced to a greater extent in the lean compared with the insulin-resistant subjects. In contrast, isolated muscle mitochondria from the type 2 subjects exhibited a greater rate of fatty acid oxidation compared with the lean group. All of these abnormalities in the type 2 diabetic group were reversed by rosiglitazone treatment. In conclusion, these studies have shown that elevated malonyl-CoA levels and decreased fatty acid oxidation are key abnormalities in insulin-resistant muscle, and, in type 2 diabetic patients, thiazolidinedione treatment can reverse these abnormalities.
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Affiliation(s)
- Gautam K Bandyopadhyay
- Department of Medicine, Division of Endocrinology and Metabolism, University of California at San Diego, 9500 Gilman Dr., La Jolla, 92093, USA
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47
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De Coppi P, Milan G, Scarda A, Boldrin L, Centobene C, Piccoli M, Pozzobon M, Pilon C, Pagano C, Gamba P, Vettor R. Rosiglitazone modifies the adipogenic potential of human muscle satellite cells. Diabetologia 2006; 49:1962-73. [PMID: 16799780 DOI: 10.1007/s00125-006-0304-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Accepted: 04/19/2006] [Indexed: 01/23/2023]
Abstract
AIMS/HYPOTHESIS Satellite cells are responsible for postnatal skeletal muscle regeneration. It has been demonstrated that mouse satellite cells behave as multipotent stem cells. We studied the differentiation capacities of human satellite cells and evaluated the effect of the insulin sensitiser rosiglitazone, a well known peroxisome proliferative activated receptor gamma (PPARG) agonist, on their adipogenic conversion. SUBJECTS, MATERIALS AND METHODS We obtained human satellite cells from human muscle biopsies of healthy subjects by single-fibre isolation and cultured them under myogenic, osteogenic and adipogenic conditions. Moreover, we compared the morphological features and the adipose-specific gene expression profiling, as assessed by quantitative PCR, between adipocytes differentiated from human satellite cells and those obtained from the stromal vascular fraction of human visceral fat. RESULTS We proved by morphological analysis, mRNA expression and immunohistochemistry that human satellite cells are able to differentiate into myotubes, adipocytes and osteocytes. The addition of rosiglitazone to the adipogenic medium strongly activated PPARG expression and enhanced adipogenesis in human satellite cells, but did not in itself trigger the complete adipogenic programme. Moreover, we observed a decrease in wingless-type MMTV integration site family member 10B and an upregulation of growth differentiation factor 8 expression, both being independent of PPARG activation. CONCLUSIONS/INTERPRETATION Human satellite cells possess a clear adipogenic potential that could explain the presence of mature adipocytes within skeletal muscle in pathological conditions such as obesity, type 2 diabetes and ageing-related sarcopenia. Rosiglitazone treatment, while enhancing adipogenesis, induces a more favourable pattern of adipocytokine expression in satellite-derived fat cells. This could partially counteract the worsening effect of intermuscular adipose tissue depots on muscle insulin sensitivity.
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Affiliation(s)
- P De Coppi
- Paediatric Oncohaematology, Stem Cell Transplantation Unit, University of Padua, via Ospedale 105, 35128 Padua, Italy
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LeBrasseur NK, Kelly M, Tsao TS, Farmer SR, Saha AK, Ruderman NB, Tomas E. Thiazolidinediones can rapidly activate AMP-activated protein kinase in mammalian tissues. Am J Physiol Endocrinol Metab 2006; 291:E175-81. [PMID: 16464908 DOI: 10.1152/ajpendo.00453.2005] [Citation(s) in RCA: 222] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Thiazolidinediones (TZDs) are insulin-sensitizing agents used in the treatment of type 2 diabetes. A widely held view is that their action is secondary to transcriptional events that occur when TZDs bind to the nuclear receptor PPARgamma in the adipocyte and stimulate adipogenesis. It has been proposed that this increases insulin sensitivity, at least in part, by increasing the expression and release of adiponectin, an adipokine that activates the fuel-sensing enzyme AMP-activated protein kinase (AMPK). In this study, we report that TZDs also acutely activate AMPK in skeletal muscle and other tissues by a mechanism that is likely independent of PPARgamma-regulated gene transcription. Thus incubation of isolated rat EDL muscles in medium containing 5 microM troglitazone for 15 min (too brief to be attributable to transcription) significantly increased pAMPK and pACC. At a concentration of 100 microM, troglitazone maximally increased these parameters and caused twofold increases in 2-deoxy-d-glucose uptake and the oxidation of exogenous [(14)C]palmitate. Time course studies revealed that troglitazone-induced increases in pAMPK and pACC abundance at 15 min were paralleled by an increase in the AMP-to-ATP ratio and that by 60 min all of these parameters had returned to baseline values. Increases in pAMPK and pACC were also observed in skeletal muscle, liver, and adipose tissue in intact rats 15 min after the administration of a single dose of troglitazone (10 mg/kg, ip). Likewise, troglitazone and another TZD, pioglitazone, caused rapid increases in pAMPK and pACC of equal magnitude in Swiss 3T3 fibroblasts with and without sufficient PPARgamma to mediate the expression of target genes. The results indicate that TZDs can act within minutes to activate AMPK in mammalian tissues. They suggest that this effect is associated with a change in cellular energy state and that it is not dependent on PPARgamma-mediated gene transcription.
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Affiliation(s)
- Nathan K LeBrasseur
- Diabetes and Metabolism Research Unit, Boston University School of Medicine, 650 Albany St., X-820, Boston, MA 02118, USA
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Gray SL, Dalla Nora E, Vidal-Puig AJ. Mouse models of PPAR-gamma deficiency: dissecting PPAR-gamma's role in metabolic homoeostasis. Biochem Soc Trans 2006; 33:1053-8. [PMID: 16246044 DOI: 10.1042/bst0331053] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The identification of humans with mutations in PPAR-gamma (peroxisome-proliferator-activated receptor-gamma) has underlined its importance in the pathogenesis of the metabolic syndrome. Genetically modified mice provide powerful tools to dissect the mechanisms by which PPAR-gamma regulates metabolic processes. Ablation of PPAR-gamma in vivo is lethal and thus dissection of PPAR-gamma function using mouse models has relied on the development of tissue and isoform-specific ablation and mouse models of human mutations. These models exhibit phenotypes of partial PPAR-gamma impairment and are useful to elucidate how PPAR-gamma regulates specific metabolic processes. These murine models have confirmed the involvement of PPAR-gamma in adipose tissue development, maintenance and distribution. The mechanism involved in PPAR-gamma regulation of glucose homoeostasis is obscure as both agonism and partial impairment of PPAR-gamma increase insulin sensitivity. While adipose tissue is likely to be the primary target for the insulin-sensitizing effects of PPAR-gamma, some murine models suggest PPAR-gamma expressed outside adipose tissue may also contribute actively to maintain glucose homoeostasis. Interestingly, mutations in PPAR-gamma that cause severe insulin resistance in humans when expressed in mice do not result in insulin insensitivity. However, these murine models can recapitulate the effects in fuel partitioning, post-prandial lipid handling and vasculature dysfunction observed in humans. In summary, these murine models of PPAR-gamma have provided useful in vivo systems to dissect the function of PPAR-gamma, but additionally have revealed a picture of complexity. These models have confirmed a key role for PPAR-gamma in the metabolic syndrome; however, they challenge the concept that insulin resistance is the main factor linking the clinical manifestations of the metabolic syndrome.
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Affiliation(s)
- S L Gray
- Department of Clinical Biochemistry, University of Cambridge, Box 232, Addenbrooke's Hospital, Level 4, Cambridge CB2 2QR, UK
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Lessard SJ, Chen ZP, Watt MJ, Hashem M, Reid JJ, Febbraio MA, Kemp BE, Hawley JA. Chronic rosiglitazone treatment restores AMPKalpha2 activity in insulin-resistant rat skeletal muscle. Am J Physiol Endocrinol Metab 2006; 290:E251-7. [PMID: 16118254 DOI: 10.1152/ajpendo.00096.2005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Rosiglitazone (RSG) is an insulin-sensitizing thiazolidinedione (TZD) that exerts peroxisome proliferator-activated receptor-gamma (PPARgamma)-dependent and -independent effects. We tested the hypothesis that part of the insulin-sensitizing effect of RSG is mediated through the action of AMP-activated protein kinase (AMPK). First, we determined the effect of acute (30-60 min) incubation of L6 myotubes with RSG on AMPK regulation and palmitate oxidation. Compared with control (DMSO), 200 microM RSG increased (P < 0.05) AMPKalpha1 activity and phosphorylation of AMPK (Thr172). In addition, acetyl-CoA carboxylase (Ser218) phosphorylation and palmitate oxidation were increased (P < 0.05) in these cells. To investigate the effects of chronic RSG treatment on AMPK regulation in skeletal muscle in vivo, obese Zucker rats were randomly allocated into two experimental groups: control and RSG. Lean Zucker rats were treated with vehicle and acted as a control group for obese Zucker rats. Rats were dosed daily for 6 wk with either vehicle (0.5% carboxymethylcellulose, 100 microl/100 g body mass), or 3 mg/kg RSG. AMPKalpha1 activity was similar in muscle from lean and obese animals and was unaffected by RSG treatment. AMPKalpha2 activity was approximately 25% lower in obese vs. lean animals (P < 0.05) but was normalized to control values after RSG treatment. ACC phosphorylation was decreased with obesity (P < 0.05) but restored to the level of lean controls with RSG treatment. Our data demonstrate that RSG restores AMPK signaling in skeletal muscle of insulin-resistant obese Zucker rats.
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Affiliation(s)
- Sarah J Lessard
- School of Medical Sciences, RMIT University, Melbourne, Victoria, Australia
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