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Salagre D, Navarro-Alarcón M, Villalón-Mir M, Alcázar-Navarrete B, Gómez-Moreno G, Tamimi F, Agil A. Chronic melatonin treatment improves obesity by inducing uncoupling of skeletal muscle SERCA-SLN mediated by CaMKII/AMPK/PGC1α pathway and mitochondrial biogenesis in female and male Zücker diabetic fatty rats. Biomed Pharmacother 2024; 172:116314. [PMID: 38387135 DOI: 10.1016/j.biopha.2024.116314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/14/2024] [Accepted: 02/17/2024] [Indexed: 02/24/2024] Open
Abstract
Melatonin acute treatment limits obesity of young Zücker diabetic fatty (ZDF) rats by non-shivering thermogenesis (NST). We recently showed melatonin chronically increases the oxidative status of vastus lateralis (VL) in both obese and lean adult male animals. The identification of VL skeletal muscle-based NST by uncoupling of sarcoendoplasmic reticulum Ca2+-ATPase (SERCA)- sarcolipin (SLN) prompted us to investigate whether melatonin is a SERCA-SLN calcium futile cycle uncoupling and mitochondrial biogenesis enhancer. Obese ZDF rats and lean littermates (ZL) of both sexes were subdivided into two subgroups: control (C) and 12 weeks orally melatonin treated (M) (10 mg/kg/day). Compared to the control groups, melatonin decreased the body weight gain and visceral fat in ZDF rats of both sexes. Melatonin treatment in both sex obese rats restored the VL muscle skin temperature and sensitized the thermogenic effect of acute cold exposure. Moreover, melatonin not only raised SLN protein levels in the VL of obese and lean rats of both sexes; also, the SERCA activity. Melatonin treatment increased the SERCA2 expression in obese and lean rats (both sexes), with no effects on SERCA1 expression. Melatonin increased the expression of thermogenic genes and proteins (PGC1-α, PPARγ, and NRF1). Furthermore, melatonin treatment enhanced the expression ratio of P-CaMKII/CaMKII and P-AMPK/AMPK. In addition, it rose mitochondrial biogenesis. These results provided the initial evidence that chronic oral melatonin treatment triggers the CaMKII/AMPK/PGC1α axis by upregulating SERCA2-SLN-mediated NST in ZDF diabetic rats of both sexes. This may further contribute to the body weight control and metabolic benefits of melatonin.
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Affiliation(s)
- D Salagre
- Department of Pharmacology, BioHealth Institute Granada (IBs Granada), Neuroscience Institute (CIBM), School of Medicine, University of Granada, Granada 18016, Spain
| | - M Navarro-Alarcón
- Department of Nutrition and Bromatology, School of Pharmacy, University of Granada, Granada 18071, Spain
| | - M Villalón-Mir
- Department of Nutrition and Bromatology, School of Pharmacy, University of Granada, Granada 18071, Spain
| | - B Alcázar-Navarrete
- CIBERES, Carlos III Health Institute, Madrid, and Pulmonology Unit, Hospital Universitario Virgen de las Nieves, Granada 18014, Spain
| | - G Gómez-Moreno
- Department of Medically Compromised Patients in Dentistry, School of Dentistry, University of Granada, Granada 18011, Spain
| | - F Tamimi
- College of Dental Medicine, QU Health, Qatar University, Doha, Qatar
| | - A Agil
- Department of Pharmacology, BioHealth Institute Granada (IBs Granada), Neuroscience Institute (CIBM), School of Medicine, University of Granada, Granada 18016, Spain.
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Nakanishi R, Tanaka M, Nisa BU, Shimizu S, Hirabayashi T, Tanaka M, Maeshige N, Roy RR, Fujino H. Alternating current electromagnetic field exposure lessens intramyocellular lipid accumulation due to high-fat feeding via enhanced lipid metabolism in mice. PLoS One 2023; 18:e0289086. [PMID: 38011220 PMCID: PMC10681264 DOI: 10.1371/journal.pone.0289086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 07/11/2023] [Indexed: 11/29/2023] Open
Abstract
Long-term high-fat feeding results in intramyocellular lipid accumulation, leading to insulin resistance. Intramyocellular lipid accumulation is related to an energy imbalance between excess fat intake and fatty acid consumption. Alternating current electromagnetic field exposure has been shown to enhance mitochondrial metabolism in the liver and sperm. Therefore, we hypothesized that alternating current electromagnetic field exposure would ameliorate high-fat diet-induced intramyocellular lipid accumulation via activation of fatty acid consumption. C57BL/6J mice were either fed a normal diet (ND), a normal diet and exposed to an alternating current electromagnetic field (ND+EMF), a high-fat diet (HFD), or a high-fat diet and exposed to an alternating current electromagnetic field (HFD+EMF). Electromagnetic field exposure was administered 8 hrs/day for 16 weeks using an alternating current electromagnetic field device (max.180 mT, Hokoen, Utatsu, Japan). Tibialis anterior muscles were collected for measurement of intramyocellular lipids, AMPK phosphorylation, FAT/CD-36, and carnitine palmitoyltransferase (CPT)-1b protein expression levels. Intramyocellular lipid levels were lower in the HFD + EMF than in the HFD group. The levels of AMPK phosphorylation, FAT/CD-36, and CPT-1b protein levels were higher in the HFD + EMF than in the HFD group. These results indicate that alternating current electromagnetic field exposure decreases intramyocellular lipid accumulation via increased fat consumption.
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Affiliation(s)
- Ryosuke Nakanishi
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
- Department of Physical Therapy, Kobe International University, Kobe, Japan
| | - Masayuki Tanaka
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
- Department of Physical Therapy, Okayama Healthcare Professional University, Okayama, Japan
| | - Badur un Nisa
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
| | - Sayaka Shimizu
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
| | - Takumi Hirabayashi
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
| | - Minoru Tanaka
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
- Department of Rehabilitation Science, Osaka Health Science University, Osaka, Japan
| | - Noriaki Maeshige
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
| | - Roland R. Roy
- Brain Research Institute and Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, United States of America
| | - Hidemi Fujino
- Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan
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Abbadessa G, Maniscalco E, Grasso L, Popara J, Di Scipio F, Franco F, Mancardi D, Pigozzi F, Borrione P, Berta GN, Racca S. Metformin Protects Rat Skeletal Muscle from Physical Exercise-Induced Injury. Biomedicines 2023; 11:2334. [PMID: 37760776 PMCID: PMC10525561 DOI: 10.3390/biomedicines11092334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 07/26/2023] [Accepted: 08/16/2023] [Indexed: 09/29/2023] Open
Abstract
Metformin (Met) is a drug commonly prescribed in type 2 diabetes mellitus. Its efficacy is due to the suppression of hepatic gluconeogenesis, enhancement of peripheral glucose uptake and lower glucose absorption by the intestine. Recent studies have reported Met efficacy in other clinical applications, such as age-related diseases. Despite the wide clinical use of Met, its mechanism of action on muscle and its effect on muscle performance are unclear. We investigated the effects of Met combined with training on physical performance (PP) in healthy rats receiving Met for 8 weeks while undergoing daily moderate exercise. We evaluated the following: PP through graded endurance exercise test performed before the beginning of the training protocol and 48 h before the end of the training period; blood ALT, AST, LDH and CK-MB levels in order to address muscle damage; and several blood and muscle myokines and the expression of factors believed to be involved in muscle adaptation to exercise. Our data demonstrate that Met does not improve the positive effects of exercise on performance, although it protects myocytes from exercise-induced damage. Moreover, given that Met positively affects exercise-induced muscle adaptation, our data support the idea of the therapeutic application of Met when muscle function and structure are compromised.
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Affiliation(s)
- Giuliana Abbadessa
- Department of Clinical and Biological Sciences, University of Turin, 10043 Orbassano, Italy; (E.M.); (L.G.); (J.P.); (F.D.S.); (F.F.); (D.M.); (S.R.)
| | - Eleonora Maniscalco
- Department of Clinical and Biological Sciences, University of Turin, 10043 Orbassano, Italy; (E.M.); (L.G.); (J.P.); (F.D.S.); (F.F.); (D.M.); (S.R.)
| | - Loredana Grasso
- Department of Clinical and Biological Sciences, University of Turin, 10043 Orbassano, Italy; (E.M.); (L.G.); (J.P.); (F.D.S.); (F.F.); (D.M.); (S.R.)
| | - Jasmin Popara
- Department of Clinical and Biological Sciences, University of Turin, 10043 Orbassano, Italy; (E.M.); (L.G.); (J.P.); (F.D.S.); (F.F.); (D.M.); (S.R.)
| | - Federica Di Scipio
- Department of Clinical and Biological Sciences, University of Turin, 10043 Orbassano, Italy; (E.M.); (L.G.); (J.P.); (F.D.S.); (F.F.); (D.M.); (S.R.)
| | - Francesco Franco
- Department of Clinical and Biological Sciences, University of Turin, 10043 Orbassano, Italy; (E.M.); (L.G.); (J.P.); (F.D.S.); (F.F.); (D.M.); (S.R.)
| | - Daniele Mancardi
- Department of Clinical and Biological Sciences, University of Turin, 10043 Orbassano, Italy; (E.M.); (L.G.); (J.P.); (F.D.S.); (F.F.); (D.M.); (S.R.)
| | - Fabio Pigozzi
- Department of Movement, Human and Health Sciences, University of Rome “Foro Italico”, 00135 Rome, Italy; (F.P.); (P.B.)
| | - Paolo Borrione
- Department of Movement, Human and Health Sciences, University of Rome “Foro Italico”, 00135 Rome, Italy; (F.P.); (P.B.)
| | - Giovanni Nicolao Berta
- Department of Clinical and Biological Sciences, University of Turin, 10043 Orbassano, Italy; (E.M.); (L.G.); (J.P.); (F.D.S.); (F.F.); (D.M.); (S.R.)
| | - Silvia Racca
- Department of Clinical and Biological Sciences, University of Turin, 10043 Orbassano, Italy; (E.M.); (L.G.); (J.P.); (F.D.S.); (F.F.); (D.M.); (S.R.)
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Handy RM, Holloway GP. Insights into the development of insulin resistance: Unraveling the interaction of physical inactivity, lipid metabolism and mitochondrial biology. Front Physiol 2023; 14:1151389. [PMID: 37153211 PMCID: PMC10157178 DOI: 10.3389/fphys.2023.1151389] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 04/07/2023] [Indexed: 05/09/2023] Open
Abstract
While impairments in peripheral tissue insulin signalling have a well-characterized role in the development of insulin resistance and type 2 diabetes (T2D), the specific mechanisms that contribute to these impairments remain debatable. Nonetheless, a prominent hypothesis implicates the presence of a high-lipid environment, resulting in both reactive lipid accumulation and increased mitochondrial reactive oxygen species (ROS) production in the induction of peripheral tissue insulin resistance. While the etiology of insulin resistance in a high lipid environment is rapid and well documented, physical inactivity promotes insulin resistance in the absence of redox stress/lipid-mediated mechanisms, suggesting alternative mechanisms-of-action. One possible mechanism is a reduction in protein synthesis and the resultant decrease in key metabolic proteins, including canonical insulin signaling and mitochondrial proteins. While reductions in mitochondrial content associated with physical inactivity are not required for the induction of insulin resistance, this could predispose individuals to the detrimental effects of a high-lipid environment. Conversely, exercise-training induced mitochondrial biogenesis has been implicated in the protective effects of exercise. Given mitochondrial biology may represent a point of convergence linking impaired insulin sensitivity in both scenarios of chronic overfeeding and physical inactivity, this review aims to describe the interaction between mitochondrial biology, physical (in)activity and lipid metabolism within the context of insulin signalling.
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Chang R, Tu TY, Hung YM, Huang JY, Chou MC, Wei JCC. Metformin use is associated with a lower risk of rotator cuff disease in patients with type 2 diabetes mellitus. DIABETES & METABOLISM 2022; 48:101368. [PMID: 35760373 DOI: 10.1016/j.diabet.2022.101368] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 06/15/2022] [Accepted: 06/17/2022] [Indexed: 11/25/2022]
Abstract
AIMS - Metformin has been mentioned to be protective against inflammation, degeneration, and oxidative stress, conditions that are associated with rotator cuff disease. To access the association between metformin use and risk of rotator cuff disease in patients with type 2 diabetes mellitus (DM). METHODS - This was a retrospective cohort study utilizing Taiwan National Health Insurance Research Database between January 1, 2000, and December 31, 2012 to retrieved participants. Metformin and propensity score matched never metformin users were determined at baseline (between the date of onset of DM and the index date), and followed to December 31, 2013. Propensity scores were adopted to address measurable confounders (including demographic variables, Diabetes Complications Severity Index, and relevant comorbidities and co-medication). A multivariable Cox proportional hazards regression model was applied to estimate the adjusted hazard ratios (HRs) for the risk of the first diagnosis of rotator cuff disease on the full cohort and on the propensity score matched cohort. RESULTS - In the propensity score matched cohort, a total of 34,964 individuals (19,416 [55.5%] men), 17,482 individuals were taking metformin, 559 [3.2%] of whom developed rotator cuff disease. Incidence of rotator cuff disease was 4.51 per 10,000 person-months in the metformin users and 5.11 in the controls. Among metformin group, the aHR (95% CI) was 0.879 (0.784-0.984) after full adjustment. The potential beneficial effect on the risk of rotator cuff disease was consistently observed across all subgroups, including sex, age, concomitant other glucose lowering drugs, and level of Diabetes Complications Severity Index (all P for interaction > 0.050). CONCLUSION - Metformin use was associated with a lower risk of rotator cuff disease in patients with type 2 DM.
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Affiliation(s)
- Renin Chang
- Department of Recreation and Sports Management, Tajen University, Pingtung, Taiwan; Department of Emergency, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.
| | - Ting-Yu Tu
- Department of Orthopedic, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.
| | - Yao-Min Hung
- Department of Internal Medicine, Kaohsiung Municipal United Hospital, Kaohsiung, Taiwan; Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; College of Health and Nursing, Meiho University, Pingtung, Taiwan.
| | - Jing-Yang Huang
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; Department of Medical Research, Chung Shan Medical University Hospital, Taichung City, Taiwan.
| | - Mei-Chia Chou
- Department of Recreation and Sports Management, Tajen University, Pingtung, Taiwan; Department of Physical Medicine and Rehabilitation, Kaohsiung Veterans General Hospital, Pingtung Branch, Pingtung, Taiwan.
| | - James Cheng-Chung Wei
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; Division of Allergy, Immunology and Rheumatology, Chung Shan Medical University Hospital; Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan; Department of Medical Research, Taichung Veterans General Hospital, Taichung, Taiwan.
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Yang L, Yang L, Wang X, Xing H, Zhao H, Xing Y, Zhou F, Wang C, Song G, Ma H. Exploring the Multi-Tissue Crosstalk Relevant to Insulin Resistance Through Network-Based Analysis. Front Endocrinol (Lausanne) 2021; 12:756785. [PMID: 35116003 PMCID: PMC8805208 DOI: 10.3389/fendo.2021.756785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 12/17/2021] [Indexed: 11/13/2022] Open
Abstract
Insulin resistance (IR) is a precursor event that occurs in multiple organs and underpins many metabolic disorders. However, due to the lack of effective means to systematically explore and interpret disease-related tissue crosstalk, the tissue communication mechanism in pathogenesis of IR has not been elucidated yet. To solve this issue, we profiled all proteins in white adipose tissue (WAT), liver, and skeletal muscle of a high fat diet induced IR mouse model via proteomics. A network-based approach was proposed to explore IR related tissue communications. The cross-tissue interface was constructed, in which the inter-tissue connections and also their up and downstream processes were particularly inspected. By functional quantification, liver was recognized as the only organ that can output abnormal carbohydrate metabolic signals, clearly highlighting its central role in regulation of glucose homeostasis. Especially, the CD36-PPAR axis in liver and WAT was identified and verified as a potential bridge that links cross-tissue signals with intracellular metabolism, thereby promoting the progression of IR through a PCK1-mediated lipotoxicity mechanism. The cross-tissue mechanism unraveled in this study not only provides novel insights into the pathogenesis of IR, but also is conducive to development of precision therapies against various IR associated diseases. With further improvement, our network-based cross-tissue analytic method would facilitate other disease-related tissue crosstalk study in the near future.
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Affiliation(s)
- Linlin Yang
- Hebei Key Laboratory of Metabolic Diseases, Shijiazhuang, China
- Clinical Medical Research Center, Hebei General Hospital, Shijiazhuang, China
| | - Linquan Yang
- Hebei Key Laboratory of Metabolic Diseases, Shijiazhuang, China
- Clinical Medical Research Center, Hebei General Hospital, Shijiazhuang, China
| | - Xing Wang
- Hebei Key Laboratory of Metabolic Diseases, Shijiazhuang, China
- Clinical Medical Research Center, Hebei General Hospital, Shijiazhuang, China
| | - Hanying Xing
- Hebei Key Laboratory of Metabolic Diseases, Shijiazhuang, China
- Clinical Medical Research Center, Hebei General Hospital, Shijiazhuang, China
| | - Hang Zhao
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
| | - Yuling Xing
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
| | - Fei Zhou
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, China
| | - Chao Wang
- Hebei Key Laboratory of Metabolic Diseases, Shijiazhuang, China
- Clinical Medical Research Center, Hebei General Hospital, Shijiazhuang, China
| | - Guangyao Song
- Hebei Key Laboratory of Metabolic Diseases, Shijiazhuang, China
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- *Correspondence: Huijuan Ma, ; Guangyao Song,
| | - Huijuan Ma
- Hebei Key Laboratory of Metabolic Diseases, Shijiazhuang, China
- Department of Endocrinology, Hebei General Hospital, Shijiazhuang, China
- *Correspondence: Huijuan Ma, ; Guangyao Song,
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Zhou B, Jia L, Zhang Z, Xiang L, Yuan Y, Zheng P, Liu B, Ren X, Bian H, Xie L, Li Y, Lu J, Zhang H, Lu Y. The Nuclear Orphan Receptor NR2F6 Promotes Hepatic Steatosis through Upregulation of Fatty Acid Transporter CD36. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2002273. [PMID: 33173745 PMCID: PMC7610302 DOI: 10.1002/advs.202002273] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Indexed: 05/08/2023]
Abstract
Nuclear receptors (NRs) are a superfamily of transcription factors which sense hormonal signals or nutrients to regulate various biological events, including development, reproduction, and metabolism. Here, this study identifies nuclear receptor subfamily 2, group F, member 6 (NR2F6), as an important regulator of hepatic triglyceride (TG) homeostasis and causal factor in the development of non-alcoholic fatty liver disease (NAFLD). Adeno-associated virus (AAV)-mediated overexpression of NR2F6 in the liver promotes TG accumulation in lean mice, while hepatic-specific suppression of NR2F6 improves obesity-associated hepatosteatosis, insulin resistance, and methionine and choline-deficient (MCD) diet-induced non-alcoholic steatohepatitis (NASH). Mechanistically, the fatty acid translocase CD36 is identified as a transcriptional target of NR2F6 to mediate its steatotic role. NR2F6 is able to bind directly onto the CD36 promoter region in hepatocytes and increases the enrichment of nuclear receptor coactivator 1 (SRC-1) and histone acetylation at its promoter. Of pathophysiological significance, NR2F6 is significantly upregulated in the livers of obese mice and NAFLD patients. Moreover, treatment with metformin decreases NR2F6 expression in obese mice, resulting in suppression of CD36 and reduced hepatic TG contents. Therefore, these results provide evidence for an unpredicted role of NR2F6 that contributes to liver steatosis and suggest that NR2F6 antagonists may present a therapeutic strategy for reversing or treating NAFLD/NASH pathogenesis.
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Affiliation(s)
- Bing Zhou
- The Key Laboratory of Metabolism and Molecular Medicine of the Ministry of EducationDepartment of Endocrinology and MetabolismFudan Institute for Metabolic DiseasesZhongshan HospitalFudan UniversityShanghai230032P. R. China
| | - Lijing Jia
- Department of EndocrinologyShenzhen People's HospitalThe Second Clinical Medical College, Jinan University, The First Affiliated Hospital of Southern University of Science and TechnologyShenzhenGuangdong518020P. R. China
| | - Zhijian Zhang
- Department of Endocrinology and MetabolismShanghai General HospitalShanghai Jiao Tong University School of MedicineShanghai201620P. R. China
| | - Liping Xiang
- The Key Laboratory of Metabolism and Molecular Medicine of the Ministry of EducationDepartment of Endocrinology and MetabolismFudan Institute for Metabolic DiseasesZhongshan HospitalFudan UniversityShanghai230032P. R. China
| | - Youwen Yuan
- Department of Endocrinology and MetabolismNanfang HospitalSouthern Medical UniversityGuangzhouGuangdong510515P. R. China
| | - Peilin Zheng
- Department of EndocrinologyShenzhen People's HospitalThe Second Clinical Medical College, Jinan University, The First Affiliated Hospital of Southern University of Science and TechnologyShenzhenGuangdong518020P. R. China
| | - Bin Liu
- The Key Laboratory of Metabolism and Molecular Medicine of the Ministry of EducationDepartment of Endocrinology and MetabolismFudan Institute for Metabolic DiseasesZhongshan HospitalFudan UniversityShanghai230032P. R. China
| | - Xingxing Ren
- The Key Laboratory of Metabolism and Molecular Medicine of the Ministry of EducationDepartment of Endocrinology and MetabolismFudan Institute for Metabolic DiseasesZhongshan HospitalFudan UniversityShanghai230032P. R. China
| | - Hua Bian
- The Key Laboratory of Metabolism and Molecular Medicine of the Ministry of EducationDepartment of Endocrinology and MetabolismFudan Institute for Metabolic DiseasesZhongshan HospitalFudan UniversityShanghai230032P. R. China
| | - Liwei Xie
- State Key Laboratory of Applied Microbiology Southern ChinaGuangdong Provincial Key Laboratory of Microbial Culture Collection and ApplicationGuangdong Open Laboratory of Applied MicrobiologyGuangdong Institute of MicrobiologyGuangdong Academy of SciencesGuangzhouGuangdong510070P. R. China
| | - Yao Li
- Department of Laboratory Animal ScienceShanghai Jiao Tong University School of MedicineShanghai200025P. R. China
| | - Jieli Lu
- Department of Endocrinology and MetabolismRuijin HospitalShanghai Jiao Tong University School of MedicineShanghai200025P. R. China
| | - Huijie Zhang
- Department of Endocrinology and MetabolismNanfang HospitalSouthern Medical UniversityGuangzhouGuangdong510515P. R. China
| | - Yan Lu
- The Key Laboratory of Metabolism and Molecular Medicine of the Ministry of EducationDepartment of Endocrinology and MetabolismFudan Institute for Metabolic DiseasesZhongshan HospitalFudan UniversityShanghai230032P. R. China
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8
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Genders AJ, Holloway GP, Bishop DJ. Are Alterations in Skeletal Muscle Mitochondria a Cause or Consequence of Insulin Resistance? Int J Mol Sci 2020; 21:ijms21186948. [PMID: 32971810 PMCID: PMC7554894 DOI: 10.3390/ijms21186948] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 09/18/2020] [Accepted: 09/18/2020] [Indexed: 12/14/2022] Open
Abstract
As a major site of glucose uptake following a meal, skeletal muscle has an important role in whole-body glucose metabolism. Evidence in humans and animal models of insulin resistance and type 2 diabetes suggests that alterations in mitochondrial characteristics accompany the development of skeletal muscle insulin resistance. However, it is unclear whether changes in mitochondrial content, respiratory function, or substrate oxidation are central to the development of insulin resistance or occur in response to insulin resistance. Thus, this review will aim to evaluate the apparent conflicting information placing mitochondria as a key organelle in the development of insulin resistance in skeletal muscle.
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Affiliation(s)
- Amanda J. Genders
- Institute for Health and Sport (iHeS), Victoria University, Melbourne 8001, Australia;
- Correspondence: ; Tel.: +61-3-9919-9556
| | - Graham P. Holloway
- Dept. Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada;
| | - David J. Bishop
- Institute for Health and Sport (iHeS), Victoria University, Melbourne 8001, Australia;
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Hameed A, Galli M, Adamska-Patruno E, Krętowski A, Ciborowski M. Select Polyphenol-Rich Berry Consumption to Defer or Deter Diabetes and Diabetes-Related Complications. Nutrients 2020; 12:E2538. [PMID: 32825710 PMCID: PMC7551116 DOI: 10.3390/nu12092538] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/11/2020] [Accepted: 08/11/2020] [Indexed: 12/20/2022] Open
Abstract
Berries are considered "promising functional fruits" due to their distinct and ubiquitous therapeutic contents of anthocyanins, proanthocyanidins, phenolic acids, flavonoids, flavanols, alkaloids, polysaccharides, hydroxycinnamic, ellagic acid derivatives, and organic acids. These polyphenols are part of berries and the human diet, and evidence suggests that their intake is associated with a reduced risk or the reversal of metabolic pathophysiologies related to diabetes, obesity, oxidative stress, inflammation, and hypertension. This work reviewed and summarized both clinical and non-clinical findings that the consumption of berries, berry extracts, purified compounds, juices, jams, jellies, and other berry byproducts aided in the prevention and or otherwise management of type 2 diabetes mellitus (T2DM) and related complications. The integration of berries and berries-derived byproducts into high-carbohydrate (HCD) and high-fat (HFD) diets, also reversed/reduced the HCD/HFD-induced alterations in glucose metabolism-related pathways, and markers of oxidative stress, inflammation, and lipid oxidation in healthy/obese/diabetic subjects. The berry polyphenols also modulate the intestinal microflora ecology by opposing the diabetic and obesity rendered symbolic reduction of Bacteroidetes/Firmicutes ratio, intestinal mucosal barrier dysfunction-restoring bacteria, short-chain fatty acids, and organic acid producing microflora. All studies proposed a number of potential mechanisms of action of respective berry bioactive compounds, although further mechanistic and molecular studies are warranted. The metabolic profiling of each berry is also included to provide up-to-date information regarding the potential anti-oxidative/antidiabetic constituents of each berry.
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Affiliation(s)
- Ahsan Hameed
- Clinical Research Center, Medical University of Bialystok, 15-089 Bialystok, Poland; (A.H.); (E.A.-P.); (A.K.)
| | - Mauro Galli
- Department of Medical Biology, Medical University of Bialystok, 15-222 Bialystok, Poland;
| | - Edyta Adamska-Patruno
- Clinical Research Center, Medical University of Bialystok, 15-089 Bialystok, Poland; (A.H.); (E.A.-P.); (A.K.)
| | - Adam Krętowski
- Clinical Research Center, Medical University of Bialystok, 15-089 Bialystok, Poland; (A.H.); (E.A.-P.); (A.K.)
- Department of Endocrinology, Diabetology, and Internal Medicine, Medical University of Bialystok, 15-089 Bialystok, Poland
| | - Michal Ciborowski
- Clinical Research Center, Medical University of Bialystok, 15-089 Bialystok, Poland; (A.H.); (E.A.-P.); (A.K.)
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Lonardo A, Lugari S, Ballestri S, Nascimbeni F, Baldelli E, Maurantonio M. A round trip from nonalcoholic fatty liver disease to diabetes: molecular targets to the rescue? Acta Diabetol 2019; 56:385-396. [PMID: 30519965 DOI: 10.1007/s00592-018-1266-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 11/27/2018] [Indexed: 02/07/2023]
Abstract
Evidence suggests a close relationship between nonalcoholic fatty liver disease (NAFLD) and type two diabetes (T2D). On the grounds of prevalence of disease, both conditions account for a significant financial cost for health care systems and individuals. Aim of this review article is to explore the epidemiological basis and the putative molecular mechanisms underlying the association of NAFLD with T2D. Epidemiological studies have shown that NAFLD is associated to the development of incident T2D and either reversal or improvement of NAFLD will result into decreased risk of developing incident T2D. On the other side of the coin data have shown that T2D will worsen the course of NAFLD doubling the risk of disease progression (i.e. evolution from simple steatosis to advanced fibrosis, cirrhosis, hepatocellular carcinoma, liver transplant and death). Conversely, NAFLD will contribute to metabolic decompensation of T2D. The pathogenesis of T2D in NAFLD patients may be mediated by several hepatokines impairing metabolic control. Among these, Fetuin-B, which causes glucose intolerance and is increased in patients with T2D and NAFLD with fibrosis is one of the most promising. T2D may affect the progression of NAFLD by acting at different levels of the pathogenic cascade involving gut microbiota and expanded, inflamed, dysfunctional adipose tissue. In conclusion, T2D and NAFLD are mutually, closely and bi-directionally associated. An improved understanding of molecular pathogenesis underlying this bi-directional association may allow us to be able to prevent the development of T2D by halting the progression of NAFLD.
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Affiliation(s)
- Amedeo Lonardo
- Azienda Ospedaliero-Universitaria Modena, UO di Medicina Metabolica, Ospedale Civile di Baggiovara, Via Giardini 1135, 41125, Modena, Italy.
| | - Simonetta Lugari
- Università di Modena e Reggio Emilia, via del Pozzo, 71, 41124, Modena, Italy
| | - Stefano Ballestri
- Azienda USL di Modena, Ospedale Di Pavullo, UO di Medicina, Pavullo (Mo), Italy
| | - Fabio Nascimbeni
- Azienda Ospedaliero-Universitaria Modena, UO di Medicina Metabolica, Ospedale Civile di Baggiovara, Via Giardini 1135, 41125, Modena, Italy
| | - Enrica Baldelli
- Università di Modena e Reggio Emilia, via del Pozzo, 71, 41124, Modena, Italy
| | - Mauro Maurantonio
- Azienda Ospedaliero-Universitaria Modena, UO di Medicina Metabolica, Ospedale Civile di Baggiovara, Via Giardini 1135, 41125, Modena, Italy
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11
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Eckstein ML, Williams DM, O'Neil LK, Hayes J, Stephens JW, Bracken RM. Physical exercise and non-insulin glucose-lowering therapies in the management of Type 2 diabetes mellitus: a clinical review. Diabet Med 2019; 36:349-358. [PMID: 30536728 DOI: 10.1111/dme.13865] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/19/2018] [Indexed: 01/05/2023]
Abstract
In the UK the National Institute of Health and Care Excellence (NICE) advocates intensive lifestyle programmes that attain the levels of daily physical activity set out by the Chief Medical Officer as a first-line strategy for improving the health of people at risk of developing diabetes or reducing the risk of development of Type 2 diabetes. For people with Type 2 diabetes, lifestyle measures complement pharmacological treatments that include both oral and injectable therapies. In line with this, NICE guidelines also support intensification of efforts to improve patient lifestyle along with these glucose-lowering therapies. There is a paucity of evidence, however, in the available published literature examining the association between glucose-lowering therapies and exercise metabolism. In the present review we explore the current knowledge with regard to the potential interactions of oral and non-insulin injectable therapies with physical activity in people at risk of, or who have, Type 2 diabetes, and present evidence that may inform healthcare professionals of the need to monitor patients more closely in their adaptation to both pharmacological therapy and physical activity.
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Affiliation(s)
- M L Eckstein
- Diabetes Research Group, Swansea University, Medical School, Swansea, UK
- Applied Sport, Technology, Exercise and Medicine Research Centre (A-STEM), College of Engineering, Swansea University, Swansea, UK
| | - D M Williams
- Diabetes Research Group, Swansea University, Medical School, Swansea, UK
- Department of Diabetes and Endocrinology, Morriston Hospital, Swansea, UK
| | - L K O'Neil
- Department of Diabetes and Endocrinology, Morriston Hospital, Swansea, UK
| | - J Hayes
- Diabetes Research Group, Swansea University, Medical School, Swansea, UK
- Department of Diabetes and Endocrinology, Morriston Hospital, Swansea, UK
| | - J W Stephens
- Diabetes Research Group, Swansea University, Medical School, Swansea, UK
- Department of Diabetes and Endocrinology, Morriston Hospital, Swansea, UK
| | - R M Bracken
- Diabetes Research Group, Swansea University, Medical School, Swansea, UK
- Applied Sport, Technology, Exercise and Medicine Research Centre (A-STEM), College of Engineering, Swansea University, Swansea, UK
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12
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She L, Xu D, Wang Z, Zhang Y, Wei Q, Aa J, Wang G, Liu B, Xie Y. Curcumin inhibits hepatic stellate cell activation via suppression of succinate-associated HIF-1α induction. Mol Cell Endocrinol 2018; 476:129-138. [PMID: 29746885 DOI: 10.1016/j.mce.2018.05.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 05/02/2018] [Accepted: 05/03/2018] [Indexed: 12/21/2022]
Abstract
PURPOSE Aberrant succinate accumulation emerges as a unifying mechanism for inflammation and oxidative stress. This study aims to investigate whether curcumin ameliorates hepatic fibrosis via blocking succinate signaling. METHODS We investigated the effects of curcumin on hepatic succinate accumulation and liver fibrosis in mice fed a high-fat diet (HFD). Meanwhile, we stimulated mouse primary hepatic stellate cells (HSCs) with succinate and observed the inhibitory effects of curcumin on succinate signaling. RESULTS Oral administration of curcumin and metformin combated mitochondrial fatty acid oxidation and reduced hepatic succinate accumulation due to the inhibition of succinate dehydrogenase (SDH) activity and demonstrated inhibitory effect on hepatic fibrosis. In mouse primary HSCs, curcumin prevented succinate- and CoCl2-induced hypoxia-inducible transcription factor-1α (HIF-1α) induction via suppression of ROS production and effectively reduced gene expressions of Col1α, Col3α, fibronectin and TGF-β1 with inflammation inhibition. Knockdown of HIF-1α with small interfering RNA blocked the action of succinate to induce HSCs activation, indicative of the essential role of HIF-1α in succinate signaling. CONCLUSIONS Hepatic succinate accumulation served as a metabolic signal to promote liver fibrosis through HIF-1α induction. Curcumin reduced succinate accumulation by combating fatty acid oxidation and prevented HSCs activation by blocking succinate/HIF-1α signaling pathway.
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Affiliation(s)
- Linlin She
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China
| | - Dan Xu
- Research and Development Center, Nanjing Chia Tai Tianqing Pharmaceutical Co., Ltd., Nanjing, 210038, China
| | - Zixia Wang
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China
| | - Yirui Zhang
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China
| | - Qingli Wei
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China
| | - Jiye Aa
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China
| | - Guangji Wang
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China
| | - Baolin Liu
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, Nanjing, 211198, China.
| | - Yuan Xie
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China.
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13
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Wang Y, Zhu J, Handberg A, Overvad K, Tjønneland A, Rimm EB, Jensen MK. Association between plasma CD36 levels and incident risk of coronary heart disease among Danish men and women. Atherosclerosis 2018; 277:163-168. [PMID: 30218892 DOI: 10.1016/j.atherosclerosis.2018.08.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 08/07/2018] [Accepted: 08/29/2018] [Indexed: 01/18/2023]
Abstract
BACKGROUND AND AIMS CD36 is a cholesterol receptor involved in the uptake of oxidized low-density lipoprotein cholesterol and development of atherosclerotic plaques. Cross-sectional studies have shown correlations between plasma CD36 and atherosclerosis but no prospective study has examined the association yet. We prospectively examined the association between plasma CD36 levels and risk of incident coronary heart disease (CHD) in a Danish population. METHODS Plasma CD36 levels were measured in a case-cohort study nested within the Danish population-based cohort, the Diet, Cancer and Health Study. A total of 1963 incident CHD events occurred between baseline (1993-1997) and 2008, and a sub-cohort of 1759 participants were randomly selected as reference. Cox proportional hazard regression models were used to compute the hazard ratio (HR) and corresponding 95% confidence interval (CI). RESULTS After adjusting for CHD risk factors, including history of hypercholesterolemia and diabetes, elevated plasma CD36 levels were not associated with higher CHD risk in the total population, and the HR comparing the highest versus lowest tertile of CD36 levels was 1.02 (95% CI: 0.84-1.23). High CD36 levels were only found to be associated with risk of CHD in combination with prevalent diabetes (HR = 2.83, 95% CI: 1.08-7.45) vs. the joint reference group of lowest CD36 tertile and no diabetes. CONCLUSIONS Plasma CD36 levels were not predictive of CHD risk in the general population.
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Affiliation(s)
- Yeli Wang
- Health Services and Systems Research, Duke-NUS Medical School, 169857, Singapore
| | - Jingwen Zhu
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Aase Handberg
- Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, 9100, Denmark; Department of Clinical Medicine, Faculty of Medicine, Aalborg University, Aalborg, 9100, Denmark
| | - Kim Overvad
- Department of Cardiology, Aalborg University Hospital, Aalborg, 9100, Denmark; Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, 8000, Denmark
| | - Anne Tjønneland
- Danish Cancer Society Research Center, Copenhagen, 2100, Denmark
| | - Eric B Rimm
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA; Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA; Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Majken K Jensen
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA; Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA.
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14
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de Bem GF, Costa CA, Santos IB, Cristino Cordeiro VDS, de Carvalho LCRM, de Souza MAV, Soares RDA, Sousa PJDC, Ognibene DT, Resende AC, de Moura RS. Antidiabetic effect of Euterpe oleracea Mart. (açaí) extract and exercise training on high-fat diet and streptozotocin-induced diabetic rats: A positive interaction. PLoS One 2018; 13:e0199207. [PMID: 29920546 PMCID: PMC6007924 DOI: 10.1371/journal.pone.0199207] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 06/04/2018] [Indexed: 12/17/2022] Open
Abstract
A growing body of evidence suggests a protective role of polyphenols and exercise training on the disorders of type 2 diabetes mellitus (T2DM). We aimed to assess the effect of the açaí seed extract (ASE) associated with exercise training on diabetic complications induced by high-fat (HF) diet plus streptozotocin (STZ) in rats. Type 2 diabetes was induced by feeding rats with HF diet (55% fat) for 5 weeks and a single dose of STZ (35 mg/kg i.p.). Control (C) and Diabetic (D) animals were subdivided into four groups each: Sedentary, Training, ASE Sedentary, and ASE Training. ASE (200 mg/kg/day) was administered by gavage and the exercise training was performed on a treadmill (30min/day; 5 days/week) for 4 weeks after the diabetes induction. In type 2 diabetic rats, the treatment with ASE reduced blood glucose, insulin resistance, leptin and IL-6 levels, lipid profile, and vascular dysfunction. ASE increased the expression of insulin signaling proteins in skeletal muscle and adipose tissue and plasma GLP-1 levels. ASE associated with exercise training potentiated the reduction of glycemia by decreasing TNF-α levels, increasing pAKT and adiponectin expressions in adipose tissue, and IR and pAMPK expressions in skeletal muscle of type 2 diabetic rats. In conclusion, ASE treatment has an antidiabetic effect in type 2 diabetic rats by activating the insulin-signaling pathway in muscle and adipose tissue, increasing GLP-1 levels, and an anti-inflammatory action. Exercise training potentiates the glucose-lowering effect of ASE by activating adiponectin-AMPK pathway and increasing IR expression.
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Affiliation(s)
- Graziele Freitas de Bem
- Department of Pharmacology, Institute of Biology, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil
| | - Cristiane Aguiar Costa
- Department of Pharmacology, Institute of Biology, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil
| | - Izabelle Barcellos Santos
- Department of Pharmacology, Institute of Biology, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil
| | | | | | | | - Ricardo de Andrade Soares
- Department of Pharmacology, Institute of Biology, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil
| | | | - Dayane Teixeira Ognibene
- Department of Pharmacology, Institute of Biology, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil
| | - Angela Castro Resende
- Department of Pharmacology, Institute of Biology, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil
- * E-mail: ,
| | - Roberto Soares de Moura
- Department of Pharmacology, Institute of Biology, Rio de Janeiro State University, Rio de Janeiro, RJ, Brazil
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15
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Musutova M, Elkalaf M, Klubickova N, Koc M, Povysil S, Rambousek J, Volckaert B, Duska F, Trinh MD, Kalous M, Trnka J, Balusikova K, Kovar J, Polak J. The Effect of Hypoxia and Metformin on Fatty Acid Uptake, Storage, and Oxidation in L6 Differentiated Myotubes. Front Endocrinol (Lausanne) 2018; 9:616. [PMID: 30386299 PMCID: PMC6199370 DOI: 10.3389/fendo.2018.00616] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 09/27/2018] [Indexed: 12/25/2022] Open
Abstract
Metabolic impairments associated with obstructive sleep apnea syndrome (OSA) are linked to tissue hypoxia, however, the explanatory molecular and endocrine mechanisms remain unknown. Using gas-permeable cultureware, we studied the chronic effects of mild and severe hypoxia on free fatty acid (FFA) uptake, storage, and oxidation in L6 myotubes under 20, 4, or 1% O2. Additionally, the impact of metformin and the peroxisome proliferator-activated receptor (PPAR) β/δ agonist, called GW501516, were investigated. Exposure to mild and severe hypoxia reduced FFA uptake by 37 and 32%, respectively, while metformin treatment increased FFA uptake by 39% under mild hypoxia. GW501516 reduced FFA uptake under all conditions. Protein expressions of CD36 (cluster of differentiation 36) and SCL27A4 (solute carrier family 27 fatty acid transporter, member 4) were reduced by 17 and 23% under severe hypoxia. Gene expression of UCP2 (uncoupling protein 2) was reduced by severe hypoxia by 81%. Metformin increased CD36 protein levels by 28% under control conditions and SCL27A4 levels by 56% under mild hypoxia. Intracellular lipids were reduced by mild hypoxia by 18%, while in controls only, metformin administration further reduced intracellular lipids (20% O2) by 36%. Finally, palmitate oxidation was reduced by severe hypoxia, while metformin treatment reduced non-mitochondrial O2 consumption, palmitate oxidation, and proton leak at all O2 levels. Hypoxia directly reduced FFA uptake and intracellular lipids uptake in myotubes, at least partially, due to the reduction in CD36 transporters. Metformin, but not GW501516, can increase FFA uptake and SCL27A4 expression under mild hypoxia. Described effects might contribute to elevated plasma FFA levels and metabolic derangements in OSA.
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Affiliation(s)
- Martina Musutova
- Department for the Study of Obesity and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Moustafa Elkalaf
- Department of Biochemistry, Cell and Molecular Biology, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Natalie Klubickova
- Department for the Study of Obesity and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Michal Koc
- Department for the Study of Obesity and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Stanislav Povysil
- Department for the Study of Obesity and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Jan Rambousek
- Department for the Study of Obesity and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Beatriz Volckaert
- Department for the Study of Obesity and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Frantisek Duska
- Department of Anesthesiology and Intensive Care, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Minh Duc Trinh
- Department for the Study of Obesity and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Martin Kalous
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czechia
| | - Jan Trnka
- Department of Biochemistry, Cell and Molecular Biology, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Kamila Balusikova
- Division of Cell and Molecular Biology, Third Faculty of Medicine, Department of Biochemistry, Cell and Molecular Biology & Center for Research of Diabetes, Metabolism and Nutrition, Charles University, Prague, Czechia
| | - Jan Kovar
- Division of Cell and Molecular Biology, Third Faculty of Medicine, Department of Biochemistry, Cell and Molecular Biology & Center for Research of Diabetes, Metabolism and Nutrition, Charles University, Prague, Czechia
| | - Jan Polak
- Department for the Study of Obesity and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czechia
- *Correspondence: Jan Polak
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16
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Trottier SK, MacPherson REK, Knuth CM, Townsend LK, Peppler WT, Mikhaeil JS, Leveille CF, LeBlanc PJ, Shearer J, Reimer RA, Wright DC. Dairy Attenuates Weight Gain to a Similar Extent as Exercise in Rats Fed a High-Fat, High-Sugar Diet. Obesity (Silver Spring) 2017; 25:1707-1715. [PMID: 28782917 DOI: 10.1002/oby.21941] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/21/2017] [Accepted: 06/22/2017] [Indexed: 01/02/2023]
Abstract
OBJECTIVE To compare the individual and combined effects of dairy and endurance exercise training in reducing weight gain and adiposity in a rodent model of diet-induced obesity. METHODS An 8-week feeding intervention of a high-fat, high-sugar diet was used to induce obesity in male Sprague-Dawley rats. Rats were then assigned to one of four groups for 6 weeks: (1) casein sedentary (casein-S), (2) casein exercise (casein-E), (3) dairy sedentary (dairy-S), and (4) dairy exercise (dairy-E). Rats were exercise trained by treadmill running 5 d/wk. RESULTS Dairy-E prevented weight gain to a greater extent than either dairy or exercise alone. Adipose tissue and liver mass were reduced to a similar extent in dairy-S, casein-E, and dairy-E groups. Differences in weight gain were not explained by food intake or total energy expenditure. The total amount of lipid excreted was greater in the dairy-S compared to casein-S and dairy-E groups. CONCLUSIONS This study provides evidence that dairy limits weight gain to a similar extent as exercise training and the combined effects are greater than either intervention alone. While exercise training reduces weight gain through increases in energy expenditure, dairy appears to increase lipid excretion in the feces.
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Affiliation(s)
- Sarah K Trottier
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Rebecca E K MacPherson
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Carly M Knuth
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Logan K Townsend
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Willem T Peppler
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - John S Mikhaeil
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Cam F Leveille
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Jane Shearer
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Raylene A Reimer
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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17
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Joannides CN, Mangiafico SP, Waters MF, Lamont BJ, Andrikopoulos S. Dapagliflozin improves insulin resistance and glucose intolerance in a novel transgenic rat model of chronic glucose overproduction and glucose toxicity. Diabetes Obes Metab 2017; 19:1135-1146. [PMID: 28244693 DOI: 10.1111/dom.12923] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 02/21/2017] [Accepted: 02/23/2017] [Indexed: 01/16/2023]
Abstract
AIM To determine whether the excretion of glucose improves insulin resistance, impaired insulin secretion or both. MATERIALS AND METHODS Appropriate methods were used to assess insulin sensitivity (euglycaemic-hyperinsulinaemic clamp) and insulin secretion (hyperglycaemic clamp) in insulin-resistant and hyperglycaemic phosphoenolpyruvate carboxykinase (PEPCK) transgenic rats after treatment with the sodium-glucose co-transporter-2 (SGLT2) inhibitor dapagliflozin. RESULTS In 14-week-old rats with hyperglycaemia, insulin resistance and glucose intolerance, 6 weeks of dapagliflozin treatment resulted in lower weight gain, plasma glucose and insulin levels, and improved glucose tolerance, associated with enhanced insulin sensitivity (rate of glucose disappearance: 51.6 ± 2.3 vs 110.6 ± 3.9 µmol/min/kg; P < .005) and glucose uptake in muscle (0.9 ± 0.1 vs 1.7 ± 0.3 µmol/min/100 g; P < .05) and fat (0.23 ± 0.04 vs 0.55 ± 0.10 µmol/min/100 g, P < .05). Additionally, adipose tissue GLUT4 protein levels were increased (0.78 ± 0.05 vs 1.20 ± 0.09 arbitrary units; P < .05), adipocyte count was higher (221.4 ± 17.7 vs 302.3 ± 21.7 per mm2 fat area; P < .05) and adipocyte size was reduced (4631.8 ± 351.5 vs 3397.6 ± 229.4 µm2 , P < .05). There was no improvement, however, in insulin secretion. To determine whether earlier intervention is necessary, 5-week-old PEPCK transgenic rats were treated with dapagliflozin for 9 weeks and insulin secretion assessed. Dapagliflozin resulted in improved plasma glucose and insulin levels, and lower weight gain but, again, insulin secretion was not improved. CONCLUSIONS In this transgenic model of low-grade chronic hyperglycaemia, SGLT2 inhibitor treatment resulted in reduced blood glucose and insulin levels and enhanced glucose tolerance, associated with improved muscle and fat insulin resistance but not improved insulin secretory function.
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Affiliation(s)
- Christos N Joannides
- Department of Medicine, Austin Hospital, University of Melbourne, Heidelberg, Victoria, Australia
| | - Salvatore P Mangiafico
- Department of Medicine, Austin Hospital, University of Melbourne, Heidelberg, Victoria, Australia
| | - Matthew F Waters
- Department of Medicine, Austin Hospital, University of Melbourne, Heidelberg, Victoria, Australia
| | - Benjamin J Lamont
- Department of Medicine, Austin Hospital, University of Melbourne, Heidelberg, Victoria, Australia
| | - Sofianos Andrikopoulos
- Department of Medicine, Austin Hospital, University of Melbourne, Heidelberg, Victoria, Australia
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18
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Lopez-Carmona MD, Plaza-Seron MC, Vargas-Candela A, Tinahones FJ, Gomez-Huelgas R, Bernal-Lopez MR. CD36 overexpression: a possible etiopathogenic mechanism of atherosclerosis in patients with prediabetes and diabetes. Diabetol Metab Syndr 2017; 9:55. [PMID: 28729885 PMCID: PMC5516302 DOI: 10.1186/s13098-017-0253-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 07/12/2017] [Indexed: 01/28/2023] Open
Abstract
RATIONALE CD36 is a scavenger receptor located on monocytes which is involved in foam cell transformation. AIM To evaluate CD36 expression under different glycemic states in both healthy subjects and in atherosclerotic patients. SUBJECTS AND METHODS In order to evaluate the possible effects of hyperglycemia on CD36 expression in healthy subjects, an in vitro experiment was carried out using monocyte in three different conditions: extreme hyperglycemia (HG), euglycemia (EG) and in the absence of glucose. On the other hand, three groups of atherosclerotic patients were evaluated according to their glycemic conditions: normoglycemic (NG), prediabetic (preDM) and diabetic (DM) patients. CD36 expression (mRNA, non-glycated and glycated protein) was analyzed in monocytes. RESULTS CD36 mRNA expression in the in vitro experiment peaked at 4 and 24 h under HG conditions. No differences in mRNA levels were found in the EG and control group. The level of non-glycated proteins was higher in HG and EG conditions compared with control group. Glycated protein expression was inhibited by glucose in a sustained manner. In atherosclerotic patients, a significant association was observed when comparing glycated CD36 protein expression in DM with NG patients (p = 0.03). No significant differences were found in mRNA and non-glycated CD36 expression in these patients. Moreover, BMI, insulin, weight and treatment were shown to be related to CD36 expression (mRNA, non-glycated and glycated protein levels, depending of the case) in atherosclerotic patients. CONCLUSIONS Hyperglycemia is an important modulator of CD36 mRNA and non-glycated protein expression in vitro, increasing de novo synthesis in healthy subjects. In atherosclerotic patients, there are progressive increases in CD36 receptors, which may be due to a post-translational stimulus.
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Affiliation(s)
- M. D. Lopez-Carmona
- Internal Medicine Department, Biomedical Institute of Malaga (IBIMA), Regional University Hospital of Malaga (Carlos Haya Hospital), Avda. Hospital Civil s/n, 29009 Malaga, Spain
| | - M. C. Plaza-Seron
- Research Laboratory-Allergy Unit, Biomedical Institute of Malaga (IBIMA), Regional University Hospital of Malaga (Carlos Haya Hospital), Malaga, Spain
| | - A. Vargas-Candela
- Internal Medicine Department, Biomedical Institute of Malaga (IBIMA), Regional University Hospital of Malaga (Carlos Haya Hospital), Avda. Hospital Civil s/n, 29009 Malaga, Spain
| | - F. J. Tinahones
- Endocrinology and Nutrition Department, Biomedical Institute of Malaga (IBIMA), Regional University Hospital of Malaga (Virgen de la Victoria Hospital), Malaga, Spain
- CIBERFisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Madrid, Spain
| | - R. Gomez-Huelgas
- Internal Medicine Department, Biomedical Institute of Malaga (IBIMA), Regional University Hospital of Malaga (Carlos Haya Hospital), Avda. Hospital Civil s/n, 29009 Malaga, Spain
- CIBERFisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Madrid, Spain
| | - M. R. Bernal-Lopez
- Internal Medicine Department, Biomedical Institute of Malaga (IBIMA), Regional University Hospital of Malaga (Carlos Haya Hospital), Avda. Hospital Civil s/n, 29009 Malaga, Spain
- CIBERFisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Madrid, Spain
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Il'yasova D, Wong BJ, Waterstone A, Kinev A, Okosun IS. Systemic F 2-Isoprostane Levels in Predisposition to Obesity and Type 2 Diabetes: Emphasis on Racial Differences. DIVERSITY AND EQUALITY IN HEALTH AND CARE 2017; 14:91-101. [PMID: 32523692 DOI: 10.21767/2049-5471.100098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This review focuses on racial differences in systemic levels of lipid peroxidation markers F2-isoprostanes as metabolic characteristics predisposing to obesity and type 2 diabetes. Elevated levels F2-isoprostanes were found in obesity, type 2 diabetes and their comorbidities. It was hypothesized that increased F2-isoprostane levels reflect the obesity-induced oxidative stress that promotes the development of type 2 diabetes. However, African Americans have lower levels of systemic F2-isoprostane levels despite their predisposition to obesity and type 2 diabetes. The review summarizes new findings from epidemiological studies and a novel interpretation of metabolic determinants of systemic F2-isoprostane levels as a favorable phenotype. Multiple observations indicate that systemic F2-isoprostane levels reflect intensity of oxidative metabolism, a major endogenous source of reactive oxygen species, and specifically, the intensity of fat utilization. Evidence from multiple human studies proposes that targeting fat metabolism can be a productive race-specific strategy to address the existing racial health disparities. Urinary F2-isoprostanes may provide the basis for targeted interventions to prevent obesity and type 2 diabetes among populations of African descent.
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Affiliation(s)
- Dora Il'yasova
- School of Public Health, Georgia State University, 140 Decatur St, Atlanta, GA, USA
| | - Brett J Wong
- Department of Kinesiology and Health, Georgia State University, 140 Decatur St, Atlanta, GA, USA
| | - Anna Waterstone
- Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC, USA
| | | | - Ike S Okosun
- School of Public Health, Georgia State University, 140 Decatur St, Atlanta, GA, USA
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20
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The effects of prenatal metformin on obesogenic diet-induced alterations in maternal and fetal fatty acid metabolism. Nutr Metab (Lond) 2016; 13:55. [PMID: 27555877 PMCID: PMC4994240 DOI: 10.1186/s12986-016-0115-9] [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: 06/29/2016] [Accepted: 08/13/2016] [Indexed: 12/21/2022] Open
Abstract
Background Maternal obesity may program the fetus and increase the susceptibility of the offspring to adult diseases. Metformin crosses the placenta and has been associated with decreased inflammation and reversal of fatty liver in obese leptin-deficient mice. We investigated the effects of metformin on maternal and fetal lipid metabolism and hepatic inflammation using a rat model of diet-induced obesity during pregnancy. Methods Female Wistar rats (6–7 weeks old) were fed normal or high calorie diets for 5 weeks. After mating with normal-diet fed males, half of the high calorie-fed dams received metformin (300 mg/kg, daily); dams (8 per group) continued diets through gestational day 19. Maternal and fetal livers and fetal brains were analyzed for fatty acids and for fatty acid metabolism-related gene expression. Data were analyzed by ANOVA followed by Dunnett’s post hoc testing. Results When compared to control-lean maternal livers, obesogenic-diet-exposed maternal livers showed significantly higher saturated fatty acids (14:0 and 16:0) and monounsaturated fatty acids (16:1n7 and 18:1n9) and lower polyunsaturated (18:2n6 and 20:4n6 [arachidonic acid]) and anti-inflammatory n3 polyunsaturated fatty acids (18:3n3 and 22:6n3 [docosahexaenoic acid]) (p < 0.05). Metformin did not affect diet-induced changes in maternal livers. Fetal livers exposed to the high calorie diet showed significantly increased saturated fatty acids (18:0) and monounsaturated fatty acids (18:1n9 and 18:1n7) and decreased polyunsaturated fatty acids (18:2n6, 20:4n6 and 22:6n3) and anti-inflammatory n3 polyunsaturated fatty acids, along with increased gene expression of fatty acid metabolism markers (Fasn, D5d, D6d, Scd1, Lxrα). Metformin significantly attenuated diet-induced inflammation and 18:1n9 and 22:6n3 in fetal livers, as well as n3 fatty acids (p < 0.05). Prenatal obesogenic diet exposure significantly increased fetal liver IFNγ levels (p < 0.05), which was reversed by maternal metformin treatment (p < 0.05). Conclusions Consumption of a high calorie diet significantly affected maternal and fetal fatty acid metabolism. It reduced anti-inflammatory polyunsaturated fatty acids in maternal and fetal livers, altered gene expression of fatty acid metabolism markers, and induced inflammation in the fetal livers. Prenatal metformin attenuated some diet-induced fatty acid changes and inflammation in the fetal livers without affecting maternal livers, suggesting that maternal metformin may impact fetal/neonatal fatty acid/lipid metabolism. Electronic supplementary material The online version of this article (doi:10.1186/s12986-016-0115-9) contains supplementary material, which is available to authorized users.
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21
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Evaluation of treadmill exercise effect on muscular lipid profiles of diabetic fatty rats by nanoflow liquid chromatography-tandem mass spectrometry. Sci Rep 2016; 6:29617. [PMID: 27388225 PMCID: PMC4937420 DOI: 10.1038/srep29617] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 06/22/2016] [Indexed: 01/01/2023] Open
Abstract
We compare comprehensive quantitative profiling of lipids at the molecular level from skeletal muscle tissues (gastrocnemius and soleus) of Zucker diabetic fatty rats and Zucker lean control rats during treadmill exercise by nanoflow liquid chromatography-tandem mass spectrometry. Because type II diabetes is caused by decreased insulin sensitivity due to excess lipids accumulated in skeletal muscle tissue, lipidomic analysis of muscle tissues under treadmill exercise can help unveil the mechanism of lipid-associated insulin resistance. In total, 314 lipid species, including phospholipids, sphingolipids, ceramides, diacylglycerols (DAGs), and triacylglycerols (TAGs), were analyzed to examine diabetes-related lipid species and responses to treadmill exercise. Most lysophospholipid levels increased with diabetes. While DAG levels (10 from the gastrocnemius and 13 from the soleus) were >3-fold higher in diabetic rats, levels of most of these decreased after exercise in soleus but not in gastrocnemius. Levels of 5 highly abundant TAGs (52:1 and 54:3 in the gastrocnemius and 48:2, 50:2, and 52:4 in the soleus) displaying 2-fold increases in diabetic rats decreased after exercise in the soleus but not in the gastrocnemius in most cases. Thus, aerobic exercise has a stronger influence on lipid levels in the soleus than in the gastrocnemius in type 2 diabetic rats.
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MacDonald TL, Ritchie KL, Davies S, Hamilton MJ, Cervone DT, Dyck DJ. Exercise training is an effective alternative to estrogen supplementation for improving glucose homeostasis in ovariectomized rats. Physiol Rep 2015; 3:3/11/e12617. [PMID: 26603453 PMCID: PMC4673645 DOI: 10.14814/phy2.12617] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 10/13/2015] [Indexed: 01/04/2023] Open
Abstract
The irreversible loss of estrogen (specifically 17-β-estradiol; E2) compromises whole-body glucose tolerance in women. Hormone replacement therapy (HRT) is frequently prescribed to treat estrogen deficiency, but has several deleterious side effects. Exercise has been proposed as an HRT substitute, however, their relative abilities to treat glucose intolerance are unknown. Thirty ovariectomized (OVX) and 20 SHAM (control) rats underwent glucose tolerance tests (GTT) 10 weeks post surgery. Area under the curve (AUC) for OVX rats was 60% greater than SHAM controls (P = 0.0005). Rats were then randomly assigned to the following treatment groups: SHAM sedentary (sed) or exercise (ex; 60 min, 5×/weeks), OVX sed, ex, or E2 (28 μg/kg bw/day) for 4 weeks. OVX ex rats experienced a ∼45% improvement in AUC relative to OVX sed rats, whereas OVX E2 underwent a partial reduction (17%; P = 0.08). Maximal insulin-stimulated glucose uptake in soleus and EDL was not impaired in OVX rats, or augmented with exercise or E2. Akt phosphorylation did not differ in soleus, EDL, or liver of any group. However, OVX ex and OVX E2 experienced greater increases in p-Akt Ser473 in VAT and SQ tissues compared with SHAM and OVX sed groups. Mitochondrial markers CS, COXIV, and core1 were increased in soleus posttraining in OVX ex rats. The content of COXIV was reduced by 52% and 61% in SQ of OVX sed and E2 rats, compared to SHAM controls, but fully restored in OVX ex rats. In summary, exercise restores glucose tolerance in OVX rats more effectively than E2. This is not reflected by alterations in muscle maximal insulin response, but increased insulin signaling in adipose depots may underlie whole-body improvements.
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Affiliation(s)
- Tara L MacDonald
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Kerry L Ritchie
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Sarah Davies
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Melissa J Hamilton
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Daniel T Cervone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David J Dyck
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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23
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Warshauer JT, Lopez X, Gordillo R, Hicks J, Holland WL, Anuwe E, Blankfard MB, Scherer PE, Lingvay I. Effect of pioglitazone on plasma ceramides in adults with metabolic syndrome. Diabetes Metab Res Rev 2015; 31:734-44. [PMID: 25959529 DOI: 10.1002/dmrr.2662] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 03/27/2015] [Accepted: 05/05/2015] [Indexed: 12/20/2022]
Abstract
BACKGROUND Metabolic syndrome (MetS) appears closely linked with ceramide accumulation, inducing insulin resistance and toxicity to multiple cell types. Animal studies demonstrate that thiazolidinediones (TZDs) reduce ceramide concentrations in plasma and skeletal muscle and support lowering of ceramide levels as a potential mediator of TZDs' mechanism of action in reducing insulin resistance; however, studies in humans have yet to be reported. This study investigated the effects of pioglitazone therapy on plasma ceramides to understand the mechanism by which TZDs improve insulin resistance in MetS. METHODS Thirty-seven subjects with MetS were studied in a single-centre, randomized, double-blind, placebo-controlled trial comparing pioglitazone to placebo. Data were collected at baseline and after 6 months of therapy. The primary endpoint was the change from baseline in plasma ceramide concentrations. RESULTS Treatment with pioglitazone for 6 months, compared with placebo, significantly reduced multiple plasma ceramide concentrations: C18:0 (p = 0.001), C20:0 (p = 0.0004), C24 : 1 (p = 0.009), dihydroceramide C18 :0 (p = 0.005), dihydroceramide C24:1 (p = 0.004), lactosylceramide C16:0 (p = 0.02) and the hexosylceramides C16:0 (p = 0.0003), C18 : 0 (p = 0.00001), C22:0 (p = 0.00002) and C24:1 (p = 0.0006). Additionally, significant reductions were found when ceramides were grouped by species: ceramides (p = 0.03), dihydroceramides (p = 0.02), hexosylceramides (p = 0.00001) and lactosylceramides (p = 0.02). The total of all measured ceramides was also significantly reduced (p = 0.001). Following treatment with pioglitazone, the decrease in some ceramide species correlated negatively with the change in insulin sensitivity (dihydroceramide C16:0, r = -0.54; p = 0.02) and positively with total (lactosylceramide C24:0, r = 0.53; p = 0.02) and high molecular weight (lactosylceramide C24:0, r = 0.48; p = 0.05) adiponectin measurements; however, significant associations with changes in liver fat and glycemic control reduction were not found. CONCLUSIONS Pioglitazone in individuals with MetS induces a potent decrease in plasma ceramides, and some of the changes correlate with changes in insulin resistance and adiponectin levels.
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Affiliation(s)
| | - Ximena Lopez
- University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ruth Gordillo
- University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jessica Hicks
- University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | - Estelle Anuwe
- University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | | | - Ildiko Lingvay
- University of Texas Southwestern Medical Center, Dallas, TX, USA
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Snook LA, Nelson EM, Dyck DJ, Wright DC, Holloway GP. Glucose-dependent insulinotropic polypeptide directly induces glucose transport in rat skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2015; 309:R295-303. [PMID: 26041107 DOI: 10.1152/ajpregu.00003.2015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 06/01/2015] [Indexed: 12/25/2022]
Abstract
Several gastrointestinal proteins have been identified to have insulinotropic effects, including glucose-dependent insulinotropic polypeptide (GIP); however, the direct effects of incretins on skeletal muscle glucose transport remain largely unknown. Therefore, the purpose of the current study was to examine the role of GIP on skeletal muscle glucose transport and insulin signaling in rats. Relative to a glucose challenge, a mixed glucose+lipid oral challenge increased circulating GIP concentrations, skeletal muscle Akt phosphorylation, and improved glucose clearance by ∼35% (P < 0.05). These responses occurred without alterations in serum insulin concentrations. In an incubated soleus muscle preparation, GIP directly stimulated glucose transport and increased GLUT4 accumulation on the plasma membrane in the absence of insulin. Moreover, the ability of GIP to stimulate glucose transport was mitigated by the addition of the PI 3-kinase (PI3K) inhibitor wortmannin, suggesting that signaling through PI3K is required for these responses. We also provide evidence that the combined stimulatory effects of GIP and insulin on soleus muscle glucose transport are additive. However, the specific GIP receptor antagonist (Pro(3))GIP did not attenuate GIP-stimulated glucose transport, suggesting that GIP is not signaling through its classical receptor. Together, the current data provide evidence that GIP regulates skeletal muscle glucose transport; however, the exact signaling mechanism(s) remain unknown.
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Affiliation(s)
- Laelie A Snook
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Emery M Nelson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David J Dyck
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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25
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Holloway TM, Bloemberg D, da Silva ML, Simpson JA, Quadrilatero J, Spriet LL. High intensity interval and endurance training have opposing effects on markers of heart failure and cardiac remodeling in hypertensive rats. PLoS One 2015; 10:e0121138. [PMID: 25803693 PMCID: PMC4372563 DOI: 10.1371/journal.pone.0121138] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 02/12/2015] [Indexed: 12/29/2022] Open
Abstract
There has been re-emerging interest and significant work dedicated to investigating the metabolic effects of high intensity interval training (HIIT) in recent years. HIIT is considered to be a time efficient alternative to classic endurance training (ET) that elicits similar metabolic responses in skeletal muscle. However, there is a lack of information on the impact of HIIT on cardiac muscle in disease. Therefore, we determined the efficacy of ET and HIIT to alter cardiac muscle characteristics involved in the development of diastolic dysfunction, such as ventricular hypertrophy, fibrosis and angiogenesis, in a well-established rodent model of hypertension-induced heart failure before the development of overt heart failure. ET decreased left ventricle fibrosis by ~40% (P < 0.05), and promoted a 20% (P<0.05) increase in the left ventricular capillary/fibre ratio, an increase in endothelial nitric oxide synthase protein (P<0.05), and a decrease in hypoxia inducible factor 1 alpha protein content (P<0.05). In contrast, HIIT did not decrease existing fibrosis, and HIIT animals displayed a 20% increase in left ventricular mass (P<0.05) and a 20% decrease in cross sectional area (P<0.05). HIIT also increased brain natriuretic peptide by 50% (P<0.05), in the absence of concomitant angiogenesis, strongly suggesting pathological cardiac remodeling. The current data support the longstanding belief in the effectiveness of ET in hypertension. However, HIIT promoted a pathological adaptation in the left ventricle in the presence of hypertension, highlighting the need for further research on the widespread effects of HIIT in the presence of disease.
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Affiliation(s)
- Tanya M. Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
- * E-mail:
| | - Darin Bloemberg
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Mayne L. da Silva
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jeremy A. Simpson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Joe Quadrilatero
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Lawrence L. Spriet
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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26
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Philp LK, Heilbronn LK, Janovska A, Wittert GA. Dietary enrichment with fish oil prevents high fat-induced metabolic dysfunction in skeletal muscle in mice. PLoS One 2015; 10:e0117494. [PMID: 25658742 PMCID: PMC4320112 DOI: 10.1371/journal.pone.0117494] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 12/24/2014] [Indexed: 11/18/2022] Open
Abstract
High saturated fat (HF-S) diets increase intramyocellular lipid, an effect ameliorated by omega-3 fatty acids in vitro and in vivo, though little is known about sex- and muscle fiber type-specific effects. We compared effects of standard chow, HF-S, and 7.5% HF-S replaced with fish oil (HF-FO) diets on the metabolic profile and lipid metabolism gene and protein content in red (soleus) and white (extensor digitorum longus) muscles of male and female C57BL/6 mice (n = 9-12/group). Weight gain was similar in HF-S- and HF-FO-fed groups. HF-S feeding increased mesenteric fat mass and lipid marker, Oil Red O, in red and mixed muscle; HF-FO increased interscapular brown fat mass. Compared to chow, HF-S and HF-FO increased expression of genes regulating triacylglycerol synthesis and fatty acid transport, HF-S suppressed genes and proteins regulating fatty acid oxidation, whereas HF-FO increased oxidative genes, proteins and enzymes and lipolytic gene content, whilst suppressing lipogenic genes. In comparison to HF-S, HF-FO further increased fat transporters, markers of fatty acid oxidation and mitochondrial content, and reduced lipogenic genes. No diet-by-sex interactions were observed. Neither diet influenced fiber type composition. However, some interactions between muscle type and diet were observed. HF-S induced changes in triacylglycerol synthesis and lipogenic genes in red, but not white, muscle, and mitochondrial biogenesis and oxidative genes were suppressed by HF-S and increased by HF-FO in red muscle only. In conclusion, HF-S feeding promotes lipid storage in red muscle, an effect abrogated by the fish oil, which increases mediators of lipolysis, oxidation and thermogenesis while inhibiting lipogenic genes. Greater storage and synthesis, and lower oxidative genes in red, but not white, muscle likely contribute to lipid accretion encountered in red muscle. Despite several gender-dimorphic genes, both sexes exhibited a similar HF-S-induced metabolic and gene expression profile; likewise fish oil was similarly protective in both sexes.
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Affiliation(s)
- Lisa K. Philp
- Discipline of Medicine, University of Adelaide, Adelaide, South Australia, Australia
- * E-mail:
| | - Leonie K. Heilbronn
- Discipline of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - Alena Janovska
- Discipline of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - Gary A. Wittert
- Discipline of Medicine, University of Adelaide, Adelaide, South Australia, Australia
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Abstract
PURPOSE OF REVIEW Despite the known glucose-lowering effects of metformin, more recent clinical interest lies in its potential as a weight loss drug. Herein, we discuss the potential mechanisms by which metformin decreases appetite and opposes unfavorable fat storage in peripheral tissues. RECENT FINDINGS Many individuals struggle to maintain clinically relevant weight loss from lifestyle and bariatric surgery interventions. Long-term follow-up from the Diabetes Prevention Program demonstrates that metformin produces durable weight loss, and decreased food intake by metformin is the primary weight loss mechanism. Although the effect of metformin on appetite is likely to be multifactorial, changes in hypothalamic physiology, including leptin and insulin sensitivity, have been documented. In addition, novel work in obesity highlights the gastrointestinal physiology and circadian rhythm changes by metformin as not only affecting food intake, but also the regulation of fat oxidation and storage in liver, skeletal muscle, and adipose tissue. SUMMARY Metformin induces modest weight loss in overweight and obese individuals at risk for diabetes. A more detailed understanding of how metformin induces weight loss will likely lead to optimal co-prescription of lifestyle modification with pharmacology for the treatment of obesity independent of diabetes.
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Affiliation(s)
- Steven K Malin
- aDepartment of Pathobiology, Lerner Research Institute, Cleveland Clinic bDepartment of Endocrinology, Diabetes and Metabolism, Cleveland Clinic, Cleveland, Ohio, USA
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28
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Variability in myosteatosis and insulin resistance induced by high-fat diet in mouse skeletal muscles. BIOMED RESEARCH INTERNATIONAL 2014; 2014:569623. [PMID: 25197650 PMCID: PMC4147206 DOI: 10.1155/2014/569623] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 07/28/2014] [Indexed: 12/17/2022]
Abstract
Nutrient overload leads to impaired muscle oxidative capacity and insulin sensitivity. However, comparative analyses of the effects of dietary manipulation on skeletal muscles with different fiber composition are lacking. This study aimed to investigate the selective adaptations in the soleus and tibialis anterior muscles evoked by administration of high-fat diet for 12 weeks in 10 mice (HFD mice) compared to 10 animals fed with a normal chow diet (control mice). Mice fed with the HFD diet exhibited hyperlipidemia, hyperinsulinemia, hyperglycemia, and lower exercise capacity in comparison to control mice. In control mice, soleus fibers showed higher lipid content than tibialis anterior fibers. In contrast, the lipid content was similar between the two muscles in HFD mice. Significant differences in markers of muscle mitochondrial production and/or activity as well as of lipid synthesis were detected between HFD mice and control mice, especially in the tibialis anterior. Moreover, translocation of GLUT-4 transporter to the plasma membrane and activation of the insulin signaling pathway were markedly inhibited in the tibialis and slightly reduced in the soleus of HFD mice compared to control mice. Overall, these results show that adaptive responses to dietary manipulation occur in a muscle-specific pattern.
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29
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Barnea M, Cohen-Yogev T, Chapnik N, Madar Z, Froy O. Effect of metformin and lipid emulsion on the circadian gene expression in muscle cells. Int J Biochem Cell Biol 2014; 53:151-61. [DOI: 10.1016/j.biocel.2014.05.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 03/23/2014] [Accepted: 05/07/2014] [Indexed: 12/16/2022]
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30
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Wessels B, Ciapaite J, van den Broek NMA, Nicolay K, Prompers JJ. Metformin impairs mitochondrial function in skeletal muscle of both lean and diabetic rats in a dose-dependent manner. PLoS One 2014; 9:e100525. [PMID: 24950069 PMCID: PMC4065055 DOI: 10.1371/journal.pone.0100525] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 05/28/2014] [Indexed: 12/02/2022] Open
Abstract
Metformin is a widely prescribed drug for the treatment of type 2 diabetes. Previous studies have demonstrated in vitro that metformin specifically inhibits Complex I of the mitochondrial respiratory chain. This seems contraindicative since muscle mitochondrial dysfunction has been linked to the pathogenesis of type 2 diabetes. However, its significance for in vivo skeletal muscle mitochondrial function has yet to be elucidated. The aim of this study was to assess the effects of metformin on in vivo and ex vivo skeletal muscle mitochondrial function in a rat model of diabetes. Healthy (fa/+) and diabetic (fa/fa) Zucker diabetic fatty rats were treated by oral gavage with metformin dissolved in water (30, 100 or 300 mg/kg bodyweight/day) or water as a control for 2 weeks. After 2 weeks of treatment, muscle oxidative capacity was assessed in vivo using 31P magnetic resonance spectroscopy and ex vivo by measuring oxygen consumption in isolated mitochondria using high-resolution respirometry. Two weeks of treatment with metformin impaired in vivo muscle oxidative capacity in a dose-dependent manner, both in healthy and diabetic rats. Whereas a dosage of 30 mg/kg/day had no significant effect, in vivo oxidative capacity was 21% and 48% lower after metformin treatment at 100 and 300 mg/kg/day, respectively, independent of genotype. High-resolution respirometry measurements demonstrated a similar dose-dependent effect of metformin on ex vivo mitochondrial function. In conclusion, metformin compromises in vivo and ex vivo muscle oxidative capacity in Zucker diabetic fatty rats in a dose-dependent manner.
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Affiliation(s)
- Bart Wessels
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Jolita Ciapaite
- Department of Pediatrics, Centre for Liver, Digestive and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Nicole M. A. van den Broek
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Klaas Nicolay
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Jeanine J. Prompers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
- * E-mail:
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Abstract
AMP-activated kinase (AMPK) is a heterotrimeric complex composed of three subunits and is the core energy sensor of the cell. The AMPK activity is important for survival during periods of stress and starvation and also has implications in type II diabetes, obesity, metabolic syndrome, longevity and cancer, etc. The activation of AMPK is triggered through binding of Adenosine Monophosphate Activated Proteins (AMP) to the Bateman domains of the gamma subunit, leading to increased phosphorylation of the threonine 172 on the alpha subunit by inducing allosteric activation and inhibiting dephosphorylation. AMPK and its subunits have been the focuses of many researchers dealing with genetic and metabolic issues. The study makes a comprehensive review on the structure, function, distribution, enzyme activity, the genetic mutation and other aspects of AMPK and its subunit genes, with the aim to outline main aspects of present researches on AMPK and its subunits in animal genetics.
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Affiliation(s)
- W Y Liu
- Faculty of Scientific and Research, Fuyang Normal College, China
| | - R S Jiang
- Department of Animal Sciences, Anhui Agricultural University, China
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32
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Stefanyk LE, Bonen A, Dyck DJ. Fatty acid transport proteins chronically relocate to the transverse-tubules in muscle from obese Zucker rats but are resistant to further insulin-induced translocation. Metabolism 2013; 62:1296-304. [PMID: 23743348 DOI: 10.1016/j.metabol.2013.04.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Revised: 04/12/2013] [Accepted: 04/29/2013] [Indexed: 12/27/2022]
Abstract
OBJECTIVES Recently, we have demonstrated that FA transport proteins are located within the t-tubule fraction of rodent muscle, and that insulin stimulation causes their translocation to this membrane fraction. Chronic relocation of the FA transport protein FAT/CD36 to the sarcolemma is observed in obese rodents and humans, and correlates with intramuscular lipid accumulation and insulin resistance. It is not known whether in an obese, insulin resistant state FA transporters also chronically relocate to the t-tubules. Furthermore, it is not known whether the insulin-stimulated translocation of the various FA transport proteins to the t-tubules is impaired in insulin resistance. METHODS Sarcolemmal and t-tubule membrane fractions were isolated via differential centrifugation from muscles of lean and obese female Zucker rats during basal or insulin stimulated conditions. FA transport proteins were measured via western blot on both membrane fractions. RESULTS Our results demonstrate that in muscle from insulin resistant Zucker rats, FAT/CD36, FABPpm and FATP1 are all increased on the t-tubules in the basal state (+72%, +120%, and +69%, respectively), potentially contributing to the accumulation of intramuscular lipids. Insulin failed to increase the content of the FA transport proteins on either the t-tubule or sarcolemma above the elevated basal levels, analogous to the well characterized impairment of insulin-stimulated GLUT4 translocation to both membrane domains in obesity. CONCLUSION FA transport proteins chronically relocate to the t-tubule domain in insulin resistant muscle, potentially contributing to lipid accumulation. Further translocation of the FA transport proteins to this domain during insulin stimulation, however, is impaired.
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Affiliation(s)
- Leslie E Stefanyk
- Department of Human Health and Nutritional Science, University of Guelph, Guelph, ON, Canada, N1G 2W1
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Role of ceramide in diabetes mellitus: evidence and mechanisms. Lipids Health Dis 2013; 12:98. [PMID: 23835113 PMCID: PMC3716967 DOI: 10.1186/1476-511x-12-98] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 06/28/2013] [Indexed: 02/06/2023] Open
Abstract
Diabetes mellitus is a metabolic disease with multiple complications that causes serious diseases over the years. The condition leads to severe economic consequences and is reaching pandemic level globally. Much research is being carried out to address this disease and its underlying molecular mechanism. This review focuses on the diverse role and mechanism of ceramide, a prime sphingolipid signaling molecule, in the pathogenesis of type 1 and type 2 diabetes and its complications. Studies using cultured cells, animal models, and human subjects demonstrate that ceramide is a key player in the induction of β-cell apoptosis, insulin resistance, and reduction of insulin gene expression. Ceramide induces β-cell apoptosis by multiple mechanisms namely; activation of extrinsic apoptotic pathway, increasing cytochrome c release, free radical generation, induction of endoplasmic reticulum stress and inhibition of Akt. Ceramide also modulates many of the insulin signaling intermediates such as insulin receptor substrate, Akt, Glut-4, and it causes insulin resistance. Ceramide reduces the synthesis of insulin hormone by attenuation of insulin gene expression. Better understanding of this area will increase our understanding of the contribution of ceramide to the pathogenesis of diabetes, and further help in identifying potential therapeutic targets for the management of diabetes mellitus and its complications.
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Obanda DN, Cefalu WT. Modulation of cellular insulin signaling and PTP1B effects by lipid metabolites in skeletal muscle cells. J Nutr Biochem 2013; 24:1529-37. [PMID: 23481236 DOI: 10.1016/j.jnutbio.2012.12.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 11/07/2012] [Accepted: 12/21/2012] [Indexed: 12/22/2022]
Abstract
Normal glucose regulation is achieved by having adequate insulin secretion and effective glucose uptake/disposal. Excess lipids in peripheral tissues - skeletal muscle, liver and adipose tissue - may attenuate insulin signaling through the protein kinase B (AKt) pathway and up-regulate protein tyrosine phosphatase 1B (PTP1B), a negative regulator of insulin signaling. We studied accumulation of lipid metabolites [triglycerides (TAGs), diglycerides (DAGs)] and ceramides in relation to insulin signaling and expression and phosphorylation of PTP1B by preincubating rat skeletal muscle cells (L6 myotubes) with three saturated and three unsaturated free fatty acids (FFAs) (200 μM). Cells were also evaluated in the presence of wortmannin, an inhibitor of phosphatidylinositol 3-kinases and thus AKt (0-100 nM). Unsaturated FFAs increased DAGs, TAGs and PTP1B expression significantly, but cells remained insulin sensitive as assessed by robust AKt and PTP1B phosphorylation at serine (Ser) 50, Ser 398 and tyrosine 152. Saturated palmitic and stearic acids increased ceramides, up-regulated PTP1B, and had AKt and PTP1B phosphorylation at Ser 50 impaired. We show a significant correlation between phosphorylation levels of AKt and of PTP1B at Ser 50 (R(2)=0.84, P<.05). The same was observed with increasing wortmannin dose (R(2)=0.73, P<.05). Only FFAs that increased ceramides caused impairment of AKt and PTP1B phosphorylation at Ser 50. PTP1B overexpression in the presence of excess lipids may not directly cause insulin resistance unless it is accompanied by decreased PTP1B phosphorylation. A clear relationship between PTP1B phosphorylation levels at Ser 50 and its negative effect on insulin signaling is shown.
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Affiliation(s)
- Diana N Obanda
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
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O'Neill HM, Holloway GP, Steinberg GR. AMPK regulation of fatty acid metabolism and mitochondrial biogenesis: implications for obesity. Mol Cell Endocrinol 2013; 366:135-51. [PMID: 22750049 DOI: 10.1016/j.mce.2012.06.019] [Citation(s) in RCA: 241] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 03/13/2012] [Accepted: 06/21/2012] [Indexed: 12/25/2022]
Abstract
Skeletal muscle plays an important role in regulating whole-body energy expenditure given it is a major site for glucose and lipid oxidation. Obesity and type 2 diabetes are causally linked through their association with skeletal muscle insulin resistance, while conversely exercise is known to improve whole body glucose homeostasis simultaneously with muscle insulin sensitivity. Exercise activates skeletal muscle AMP-activated protein kinase (AMPK). AMPK plays a role in regulating exercise capacity, skeletal muscle mitochondrial content and contraction-stimulated glucose uptake. Skeletal muscle AMPK is also thought to be important for regulating fatty acid metabolism; however, direct genetic evidence in this area is currently lacking. This review will discuss the current paradigms regarding the influence of AMPK in regulating skeletal muscle fatty acid metabolism and mitochondrial biogenesis at rest and during exercise, and highlight the potential implications in the development of insulin resistance.
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Affiliation(s)
- Hayley M O'Neill
- University of Melbourne, Department of Medicine, St. Vincent's Institute of Medical Research, Melbourne, Victoria, Australia.
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Malin SK, Nightingale J, Choi SE, Chipkin SR, Braun B. Metformin modifies the exercise training effects on risk factors for cardiovascular disease in impaired glucose tolerant adults. Obesity (Silver Spring) 2013; 21:93-100. [PMID: 23505172 PMCID: PMC3499683 DOI: 10.1002/oby.20235] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 04/30/2012] [Indexed: 12/25/2022]
Abstract
UNLABELLED Impaired glucose tolerant (IGT) adults are at elevated risk for cardiovascular disease (CVD). Exercise or metformin reduce CVD risk, but the efficacy of combining treatments is unclear. OBJECTIVE To determine the effects of exercise training plus metformin (EM), compared with each treatment alone, on CVD risk factors in IGT adults. DESIGN AND METHODS Subjects were assigned to placebo (P), metformin (M), exercise training plus placebo (EP), or EM (8/group). In a double-blind design, P or 2,000 mg/d of M were administered for 12 weeks and half performed aerobic and resistance training 3 days/week for ≈ 60 min/day at 70% pretraining heart rate peak. Outcomes included adiposity, blood pressure (BP), lipids, and high sensitivity C-reactive protein (hs-CRP). Z-scores were calculated to determine metabolic syndrome severity. RESULTS M and EM, but not EP, decreased body weight compared with P (P < 0.05). M and EP lowered systolic blood pressure by 6% (P < 0.05), diastolic blood pressure by 6% (P < 0.05), and hs-CRP by 20% (M: trend P = 0.06; EP: P < 0.05) compared with P. Treatments raised high-density lipoprotein cholesterol (P < 0.05; EM: trend P = 0.06) compared with P and lowered triacyglycerol (P < 0.05) and metabolic syndrome Z-score compared with baseline (EP; trend P = 0.07 and EM or M; P < 0.05). CONCLUSIONS Although exercise and/or metformin improve some CVD risk factors, only training or metformin alone lowered hs-CRP and BP. Thus, metformin may attenuate the effects of training on some CVD risk factors and metabolic syndrome severity in IGT adults.
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Affiliation(s)
- Steven K. Malin
- Energy Metabolism Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA 01003
| | - Joy Nightingale
- Energy Metabolism Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA 01003
| | - Sung-Eun Choi
- Department of Family, Nutrition, and Exercise Sciences, Queens College, Flushing, NY
| | - Stuart R. Chipkin
- Energy Metabolism Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA 01003
| | - Barry Braun
- Energy Metabolism Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA 01003
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Erickson KA, Smith ME, Anthonymuthu TS, Evanson MJ, Brassfield ES, Hodson AE, Bressler MA, Tucker BJ, Thatcher MO, Prince JT, Hancock CR, Bikman BT. AICAR inhibits ceramide biosynthesis in skeletal muscle. Diabetol Metab Syndr 2012; 4:45. [PMID: 23134616 PMCID: PMC3514253 DOI: 10.1186/1758-5996-4-45] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 11/05/2012] [Indexed: 02/28/2023] Open
Abstract
BACKGROUND The worldwide prevalence of obesity has lead to increased efforts to find therapies to treat obesity-related pathologies. Ceramide is a well-established mediator of several health problems that arise from adipose tissue expansion. The purpose of this study was to determine whether AICAR, an AMPK-activating drug, selectively reduces skeletal muscle ceramide synthesis. METHODS Murine myotubes and rats were challenged with palmitate and high-fat diet, respectively, to induce ceramide accrual, in the absence or presence of AICAR. Transcript levels of the rate-limiting enzyme in ceramide biosynthesis, serine palmitoyltransferase 2 (SPT2) were measured, in addition to lipid analysis. Student's t-test and ANOVA were used to assess the association between outcomes and groups. RESULTS Palmitate alone induced an increase in serine palmitoyltransferase 2 (SPT2) expression and an elevation of ceramide levels in myotubes. Co-incubation with palmitate and AICAR prevented both effects. However, ceramide and SPT2 increased with the addition of compound C, an AMPK inhibitor. In rats fed a high-fat diet (HFD), soleus SPT2 expression increased compared with normal chow-fed littermates. Moreover, rats on HFD that received daily AICAR injections had lower SPT2 levels and reduced muscle ceramide content compared with those on HFD only. CONCLUSIONS These results suggest that AICAR reduces ceramide synthesis by targeting SPT2 transcription, likely via AMPK activation as AMPK inhibition prevented the AICAR-induced improvements. Given the role of skeletal muscle ceramide in insulin resistance, it is tempting to speculate that interventions that activate AMPK may lead to long-term ceramide reduction and improved metabolic function.
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Affiliation(s)
- Katherine A Erickson
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - Melissa E Smith
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | | | - Michael J Evanson
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - Eric S Brassfield
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - Aimee E Hodson
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - M Andrew Bressler
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - Braden J Tucker
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - Mikayla O Thatcher
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
| | - John T Prince
- Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Chad R Hancock
- Nutrition, Dietetics, and Food Science, Brigham Young University, Provo, UT 84602, USA
| | - Benjamin T Bikman
- Physiology and Developmental Biology, Brigham Young University, 593 WIDB, Provo, UT 84602, USA
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Jenkins NT, Padilla J, Arce-Esquivel AA, Bayless DS, Martin JS, Leidy HJ, Booth FW, Rector RS, Laughlin MH. Effects of endurance exercise training, metformin, and their combination on adipose tissue leptin and IL-10 secretion in OLETF rats. J Appl Physiol (1985) 2012; 113:1873-83. [PMID: 23019312 DOI: 10.1152/japplphysiol.00936.2012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Adipose tissue inflammation plays a role in cardiovascular (CV) and metabolic diseases associated with obesity, insulin resistance, and type 2 diabetes mellitus (T2DM). The interactive effects of exercise training and metformin, two first-line T2DM treatments, on adipose tissue inflammation are not known. Using the hyperphagic, obese, insulin-resistant Otsuka Long-Evans Tokushima Fatty (OLETF) rat model, we tested the hypothesis that treadmill training, metformin, or a combination of these reduces the secretion of proinflammatory cytokines from adipose tissue. Compared with Long-Evans Tokushima Otsuka (LETO) control rats (L-Sed), sedentary OLETF (O-Sed) animals secreted significantly greater amounts of leptin from retroperitoneal adipose tissue. Conversely, secretion of interleukin (IL)-10 by O-Sed adipose tissue was lower than that in L-Sed animals. Examination of leptin and IL-10 secretion from adipose tissue in OLETF groups treated with endurance exercise training (O-EndEx), metformin treatment (O-Met), and a combination of these (O-E+M) from 20 to 32 wk of age indicated that 1) leptin secretion from adipose tissue was reduced in O-Met and O-E+M, but not O-EndEx animals; 2) adipose tissue IL-10 secretion was increased in O-EndEx and O-E+M but not in O-Met animals; and 3) only the combined treatment (O-E+M) displayed both a reduction in leptin secretion and an increase in IL-10 secretion. Leptin and IL-10 concentrations in adipose tissue-conditioned buffers were correlated with their plasma concentrations, adipocyte diameters, and total adiposity. Overall, this study indicates that exercise training and metformin have additive influences on adipose tissue secretion and plasma concentrations of leptin and IL-10.
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Affiliation(s)
- Nathan T Jenkins
- Department of 1Biomedical Sciences, University of Missouri, Columbia, MO 65211, USA.
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Mercken EM, Carboneau BA, Krzysik-Walker SM, de Cabo R. Of mice and men: the benefits of caloric restriction, exercise, and mimetics. Ageing Res Rev 2012; 11:390-8. [PMID: 22210414 DOI: 10.1016/j.arr.2011.11.005] [Citation(s) in RCA: 212] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 11/09/2011] [Accepted: 11/18/2011] [Indexed: 12/25/2022]
Abstract
During aging there is an increasing imbalance of energy intake and expenditure resulting in obesity, frailty, and metabolic disorders. For decades, research has shown that caloric restriction (CR) and exercise can postpone detrimental aspects of aging. These two interventions invoke a similar physiological signature involving pathways associated with stress responses and mitochondrial homeostasis. Nonetheless, CR is able to delay aging processes that result in an increase of both mean and maximum lifespan, whereas exercise primarily increases healthspan. Due to the strict dietary regime necessary to achieve the beneficial effects of CR, most studies to date have focused on rodents and non-human primates. As a consequence, there is vast interest in the development of compounds such as resveratrol, metformin and rapamycin that would activate the same metabolic- and stress-response pathways induced by these interventions without actually restricting caloric intake. Therefore the scope of this review is to (i) describe the benefits of CR and exercise in healthy individuals, (ii) discuss the role of these interventions in the diseased state, and (iii) examine some of the promising pharmacological alternatives such as CR- and exercise-mimetics.
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Chabowski A, Zendzian-Piotrowska M, Nawrocki A, Górski J. Not only accumulation, but also saturation status of intramuscular lipids is significantly affected by PPARγ activation. Acta Physiol (Oxf) 2012; 205:145-58. [PMID: 22023892 DOI: 10.1111/j.1748-1716.2011.02380.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
AIM Intramuscular lipid accumulation has been associated with insulin resistance, and after thiazolidinediones (TZD) treatment, it was shown to be reduced in some, but not all, studies. This work was undertaken to investigate the relationships between intramuscular lipids [free fatty acids (FFA), diacylglycerols (DAG), triacylglycerol (TAG) and phospholipids] and plasmalemmal expression of fatty acid (FA) transporter [FAT/CD36 and FABPpm] in the muscles of varying oxidative capacity, after peroxisome proliferator-activated receptors gamma (PPARγ) activation (rosiglitazone) in an animal model of high-fat-diet-induced insulin resistance. Endurance training was also included to further explore the differences in these relationships. METHODS We have used gas liquid chromatography to estimate FA content and composition in each lipid fraction. For sarcolemmal expression of FA transporters, subfractionation of skeletal muscles with subsequent western blot technique was applied. RESULTS High-fat diet induced intramuscular accumulation of FFA, DAG and TAG, irrespective of muscle's fibre composition. PPARγ activation (rosiglitazone) and, to a lesser extent, endurance training further increased TAG accumulation, while it reduced DAG in oxidative muscles (soleus and red gastrocnemius). Aforementioned interventions increased also sarcolemmal FAT/CD36 and FABPpm expressions in particular muscles. Irrespective of diet, rosiglitazone and exercise decreased significantly FA saturation status favouring proportionate enhancement in monounsaturated FA (rosiglitazone) or polyunsaturated FAs (endurance training). CONCLUSION These findings support the conclusion that not only the change in total lipid content (DAG and TAG), but also FA composition is affected by rosiglitazone in an animal model of high-fat-diet-induced insulin resistance.
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Affiliation(s)
- A Chabowski
- Department of Physiology, Medical University of Bialystok, Poland.
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Delghingaro-Augusto V, Décary S, Peyot ML, Latour MG, Lamontagne J, Paradis-Isler N, Lacharité-Lemieux M, Akakpo H, Birot O, Nolan CJ, Prentki M, Bergeron R. Voluntary running exercise prevents β-cell failure in susceptible islets of the Zucker diabetic fatty rat. Am J Physiol Endocrinol Metab 2012; 302:E254-64. [PMID: 22045312 DOI: 10.1152/ajpendo.00360.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Physical activity improves glycemic control in type 2 diabetes (T2D), but its contribution to preserving β-cell function is uncertain. We evaluated the role of physical activity on β-cell secretory function and glycerolipid/fatty acid (GL/FA) cycling in male Zucker diabetic fatty (ZDF) rats. Six-week-old ZDF rats engaged in voluntary running for 6 wk (ZDF-A). Inactive Zucker lean and ZDF (ZDF-I) rats served as controls. ZDF-I rats displayed progressive hyperglycemia with β-cell failure evidenced by falling insulinemia and reduced insulin secretion to oral glucose. Isolated ZDF-I rat islets showed reduced glucose-stimulated insulin secretion expressed per islet and per islet protein. They were also characterized by loss of the glucose regulation of fatty acid oxidation and GL/FA cycling, reduced mRNA expression of key β-cell genes, and severe reduction of insulin stores. Physical activity prevented diabetes in ZDF rats through sustaining β-cell compensation to insulin resistance shown in vivo and in vitro. Surprisingly, ZDF-A islets had persistent defects in fatty acid oxidation, GL/FA cycling, and β-cell gene expression. ZDF-A islets, however, had preserved islet insulin mRNA and insulin stores compared with ZDF-I rats. Physical activity did not prevent hyperphagia, dyslipidemia, or obesity in ZDF rats. In conclusion, islets of ZDF rats have a susceptibility to failure that is possibly due to altered β-cell fatty acid metabolism. Depletion of pancreatic islet insulin stores is a major contributor to islet failure in this T2D model, preventable by physical activity.
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Affiliation(s)
- Viviane Delghingaro-Augusto
- Molecular Nutrition Unit and The Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center,University of Montreal, Quebec, Canada
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Helge JW, Tobin L, Drachmann T, Hellgren LI, Dela F, Galbo H. Muscle ceramide content is similar after 3 weeks’ consumption of fat or carbohydrate diet in a crossover design in patients with type 2 diabetes. Eur J Appl Physiol 2011; 112:911-8. [DOI: 10.1007/s00421-011-2041-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Accepted: 06/03/2011] [Indexed: 12/25/2022]
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Koonen DPY, Jensen MK, Handberg A. Soluble CD36- a marker of the (pathophysiological) role of CD36 in the metabolic syndrome? Arch Physiol Biochem 2011; 117:57-63. [PMID: 21250778 DOI: 10.3109/13813455.2010.543136] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CD36 is a class B scavenger receptor observed in many cell types and tissues throughout the body. Recent literature has implicated CD36 in the pathogenesis of metabolic dysregulation such as found in obesity, insulin resistance, and atherosclerosis. Genetic variation at the CD36 loci have been associated with obesity and lipid components of the metabolic syndrome, with risk of heart disease and type 2 diabetes. Recently, non-cell bound CD36 was identified in human plasma and was termed soluble CD36 (sCD36). In this review we will describe the functions of CD36 in tissues and address the role of sCD36 in the context of the metabolic syndrome. We will also highlight recent findings from human genetic studies looking at the CD36 locus in relation to metabolic profile in the general population. Finally, we present a model in which insulin resistance, oxLDL, low-grade inflammation and liver steatosis may contribute to elevated levels of sCD36.
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Affiliation(s)
- Debby P Y Koonen
- Molecular Genetics, Department of Pathology and Medical Biology, University Medical Center Groningen, The Netherlands
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Stefanyk LE, Gulli RA, Ritchie IR, Chabowski A, Snook LA, Bonen A, Dyck DJ. Recovered insulin response by 2 weeks of leptin administration in high-fat fed rats is associated with restored AS160 activation and decreased reactive lipid accumulation. Am J Physiol Regul Integr Comp Physiol 2011; 301:R159-71. [PMID: 21525176 DOI: 10.1152/ajpregu.00636.2010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leptin is an adipokine that increases fatty acid (FA) oxidation, decreases intramuscular lipid stores, and improves insulin response in skeletal muscle. In an attempt to elucidate the underlying mechanisms by which these metabolic changes occur, we administered leptin (Lep) or saline (Sal) by miniosmotic pumps to rats during the final 2 wk of a 6-wk low-fat (LF) or high-fat (HF) diet. Insulin-stimulated glucose transport was impaired by the HF diet (HF-Sal) but was restored with leptin administration (HF-Lep). This improvement was associated with restored phosphorylation of Akt and AS160 and decreased in reactive lipid species (ceramide, diacylglycerol), known inhibitors of the insulin-signaling cascade. Total muscle citrate synthase (CS) activity was increased by both leptin and HF diet, but was not additive. Leptin increased subsarcolemmal (SS) and intramyofibrillar (IMF) mitochondria CS activity. Total muscle, sarcolemmal, and mitochondrial (SS and IMF) FA transporter (FAT/CD36) protein content was significantly increased with the HF diet, but not altered by leptin. Therefore, the decrease in reactive lipid stores and subsequent improvement in insulin response, secondary to leptin administration in rats fed a HF diet was not due to a decrease in FA transport protein content or altered cellular distribution.
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Affiliation(s)
- Leslie E Stefanyk
- Dept. of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada, N1G 2W1
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A grape polyphenol extract modulates muscle membrane fatty acid composition and lipid metabolism in high-fat--high-sucrose diet-fed rats. Br J Nutr 2011; 106:491-501. [PMID: 21554810 DOI: 10.1017/s0007114511000602] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Accumulation of muscle TAG content and modification of muscle phospholipid fatty acid pattern may have an impact on lipid metabolism, increasing the risk of developing diabetes. Some polyphenols have been reported to modulate lipid metabolism, in particular those issued from red grapes. The present study was designed to determine whether a grape polyphenol extract (PPE) modulates skeletal muscle TAG content and phospholipid fatty acid composition in high-fat-high-sucrose (HFHS) diet-fed rats. Muscle plasmalemmal and mitochondrial fatty acid transporters, GLUT4 and lipid metabolism pathways were also explored. The PPE decreased muscle TAG content in HFHS/PPE diet-fed rats compared with HFHS diet-fed rats and induced higher proportions of n-3 PUFA in phospholipids. The PPE significantly up-regulated GLUT4 mRNA expression. Gene and protein expression of muscle fatty acid transporter cluster of differentiation 36 (CD36) was increased in HFHS diet-fed rats but returned to control values in HFHS/PPE diet-fed rats. Carnitine palmitoyltransferase 1 protein expression was decreased with the PPE. Mitochondrial β-hydroxyacyl CoA dehydrogenase was increased in HFHS diet-fed rats and returned to control values with PPE supplementation. Lipogenesis, mitochondrial biogenesis and mitochondrial activity were not affected by the PPE. In conclusion, the PPE modulated membrane phospholipid fatty acid composition and decreased muscle TAG content in HFHS diet-fed rats. The PPE lowered CD36 gene and protein expression, probably decreasing fatty acid transport and lipid accumulation within skeletal muscle, and increased muscle GLUT4 expression. These effects of the PPE are in favour of a better insulin sensibility.
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Dong SF, Hong Y, Liu M, Hao YZ, Yu HS, Liu Y, Sun JN. Berberine attenuates cardiac dysfunction in hyperglycemic and hypercholesterolemic rats. Eur J Pharmacol 2011; 660:368-74. [PMID: 21458442 DOI: 10.1016/j.ejphar.2011.03.024] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Revised: 01/24/2011] [Accepted: 03/15/2011] [Indexed: 11/13/2022]
Abstract
The positive effects of berberine (30 mg/kg/day, i.g. for 6 weeks) on cardiac dysfunction were evaluated in the rat model of hyperglycemia and hypercholesterolemia. Hyperglycemia and hypercholesterolemia were induced by feeding high-sucrose/fat diet (HSFD) consisting of 20% sucrose, 10% lard, 2.5% cholesterol, 1% bile salt for 12 weeks and streptozotocin (30 mg/kg, i.p.). The plasma sugar, total cholesterol, and triglyceride levels were significantly increased (422, 194 and 82%, respectively) in the HSFD/streptozotocin-treated rats, when compared with control animals receiving normal diet and vehicle. Berberine treatment reduced the plasma sugar and lipid levels by 24-69% in the rat model of hyperglycemia and hypercholesterolemia. Cardiac functions signed as values of cardiac output, left ventricular systolic pressure, the maximum rate of myocardial contraction (+dp/dtmax), left ventricular end diastolic pressure and the maximum rate of myocardial diastole (-dp/dtmax) were injured by 16-55% in the hyperglycemic/hypercholesterolemic rats. Berberine increased cardiac output, left ventricular systolic pressure and +dp/dtmax by 64, 16 and 79%, but decreased left ventricular end diastolic pressure and -dp/dtmax by 121 and 61% in the rats receiving HSFD/streptozotocin, respectively, when compared with the drug-untreated rats of hyperglycemia and hypercholesterolemia. Berberine caused significant increase in cardiac fatty acid transport protein-1 (159%), fatty acid transport proteins (56%), fatty acid beta-oxidase (52%), as well as glucose transporter-4 and peroxisome proliferator-activated receptor-γ (PPARγ), but decrease in PPARα mRNA and protein expression in hyperglycemic/hypercholesterolemic rats. These results indicated that berberine exerted protective effects on cardiac dysfunction induced by hyperglycemia/hypercholesterolemia through alleviating cardiac lipid accumulation and promoting glucose transport.
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Affiliation(s)
- Shi-Fen Dong
- Department of Pharmacology, Beijing University of Chinese Medicine, Beijing 100029, China
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Takiyama Y, Harumi T, Watanabe J, Fujita Y, Honjo J, Shimizu N, Makino Y, Haneda M. Tubular injury in a rat model of type 2 diabetes is prevented by metformin: a possible role of HIF-1α expression and oxygen metabolism. Diabetes 2011; 60:981-92. [PMID: 21282369 PMCID: PMC3046859 DOI: 10.2337/db10-0655] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVE Chronic hypoxia has been recognized as a key regulator in renal tubulointerstitial fibrosis, as seen in diabetic nephropathy, which is associated with the activation of hypoxia-inducible factor (HIF)-1α. We assess here the effects of the biguanide, metformin, on the expression of HIF-1α in diabetic nephropathy using renal proximal tubular cells and type 2 diabetic rats. RESEARCH DESIGN AND METHODS We explored the effects of metformin on the expression of HIF-1α using human renal proximal tubular epithelial cells (HRPTECs). Male Zucker diabetic fatty (ZDF; Gmi-fa/fa) rats were treated from 9 to 39 weeks with metformin (250 mg ⋅ kg(-1) ⋅ day(-1)) or insulin. RESULTS Metformin inhibited hypoxia-induced HIF-1α accumulation and the expression of HIF-1-targeted genes in HRPTECs. Although metformin activated the downstream pathways of AMP-activated protein kinase (AMPK), neither the AMPK activator, AICAR, nor the mTOR inhibitor, rapamycin, suppressed hypoxia-induced HIF-1α expression. In addition, knockdown of AMPK-α did not abolish the inhibitory effects of metformin on HIF-1α expression. The proteasome inhibitor, MG-132, completely eradicated the suppression of hypoxia-induced HIF-1α accumulation by metformin. The inhibitors of mitochondrial respiration similarly suppressed hypoxia-induced HIF-1α expression. Metformin significantly decreased ATP production and oxygen consumption rates, which subsequently led to increased cellular oxygen tension. Finally, metformin, but not insulin, attenuated tubular HIF-1α expression and pimonidazole staining and ameliorated tubular injury in ZDF rats. CONCLUSIONS Our data suggest that hypoxia-induced HIF-1α accumulation in diabetic nephropathy could be suppressed by the antidiabetes drug, metformin, through the repression of oxygen consumption.
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Affiliation(s)
- Yumi Takiyama
- Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Asahikawa, Japan.
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Exercise-induced, but not creatine-induced, decrease in intramyocellular lipid content improves insulin sensitivity in rats. J Nutr Biochem 2011; 22:1178-85. [PMID: 21333514 DOI: 10.1016/j.jnutbio.2010.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 09/23/2010] [Accepted: 10/01/2010] [Indexed: 11/23/2022]
Abstract
The effect of creatine supplementation, alone or in combination with exercise training, on insulin sensitivity, intramyocellular lipid content (IMCL) and fatty acid translocase (FAT)/CD36 content was investigated in rats fed a sucrose-rich cafeteria diet during 12 weeks. Five experimental conditions were CON, receiving normal pellets; CAF, fed the cafeteria diet; CAF(TR), fed the cafeteria diet together with exercise training in weeks 8-12 and CAF(CR) and CAF(CRT) that were analogous to CAF and CAF(TR), respectively, but which received daily 2.5% of creatine monohydrate. During intravenous glucose tolerance test, compared with CON, whole-body glucose tolerance was reduced in CAF and CAF(CR) but not in CAF(TR) and CAF(CRT). Insulin-stimulated glucose transport in perfused red gastrocnemius muscles was impaired in CAF and CAF(CR) but not in the trained groups. IMCL content in soleus and extensor digitorum longus muscles was higher in CAF than in CON, but not in CAF(TR), CAF(CR) and CAF(CRT). Compared with CON and CAF, FAT/CD36 protein content in m. soleus, was ~40% lower in CAF(CR), CAF(TR) and CAF(CRT). The fraction of fecal fat, as determined in a 3-week post hoc study, was 25% higher in CAF(CR) than in CON. Moreover, in CAF(CR), triglyceride concentration in blood and liver were significantly lower than in CAF. It is concluded that creatine supplementation in rats on a cafeteria diet inhibits IMCL accumulation via inhibition of gastrointestinal lipid absorption together with lower muscle FAT/CD36 content. Furthermore, exercise-induced but not creatine-induced reduction of IMCL is associated with improved insulin action on glucose transport in muscle cells.
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Thrush AB, Harasim E, Chabowski A, Gulli R, Stefanyk L, Dyck DJ. A single prior bout of exercise protects against palmitate-induced insulin resistance despite an increase in total ceramide content. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1200-8. [PMID: 21325642 DOI: 10.1152/ajpregu.00091.2010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Ceramide accumulation has been implicated in the impairment of insulin-stimulated glucose transport in skeletal muscle following saturated fatty acid (FA) exposure. Importantly, a single bout of exercise can protect against acute lipid-induced insulin resistance. The mechanism by which exercise protects against lipid-induced insulin resistance is not completely known but may occur through a redirection of FA toward triacylglycerol (TAG) and away from ceramide and diacylglycerol (DAG). Therefore, in the current study, an in vitro preparation was used to examine whether a prior bout of exercise could confer protection against palmitate-induced insulin resistance and whether the pharmacological [50 μM fumonisin B(1) (FB1)] inhibition of ceramide synthesis in the presence of palmitate could mimic the protective effect of exercise. Soleus muscle of sedentary (SED), exercised (EX), and SED in the presence of FB1 (SED+FB1) were incubated with or without 2 mM palmitate for 4 h. This 2-mM palmitate exposure impaired insulin-stimulated glucose transport (-28%, P < 0.01) and significantly increased ceramide, DAG, and TAG accumulation in the SED group (P < 0.05). A single prior bout of exercise prevented the detrimental effects of palmitate on insulin signaling and caused a partial redistribution of FA toward TAG (P < 0.05). However, the net increase in ceramide content in response to palmitate exposure in the EX group was not different compared with SED, despite the maintenance of insulin sensitivity. The incubation of soleus from SED rats with FB1 (SED+FB1) prevented the detrimental effects of palmitate and caused a redirection of FA toward TAG accumulation (P < 0.05). Therefore, this research suggests that although inhibiting ceramide accumulation can prevent the detrimental effects of palmitate, a single prior bout of exercise appears to protect against palmitate-induced insulin resistance, which may be independent of changes in ceramide content.
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Affiliation(s)
- A Brianne Thrush
- Dept. of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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Ritchie IRW, Gulli RA, Stefanyk LE, Harasim E, Chabowski A, Dyck DJ. Restoration of skeletal muscle leptin response does not precede the exercise-induced recovery of insulin-stimulated glucose uptake in high-fat-fed rats. Am J Physiol Regul Integr Comp Physiol 2010; 300:R492-500. [PMID: 21084675 DOI: 10.1152/ajpregu.00602.2010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Leptin administration increases fatty acid (FA) oxidation rates and decreases lipid storage in oxidative skeletal muscle, thereby improving insulin response. We have previously shown high-fat (HF) diets to rapidly induce skeletal muscle leptin resistance, prior to the disruption of normal muscle FA metabolism (increase in FA transport; accumulation of triacylglycerol, diacylglycerol, ceramide) that occurs in advance of impaired insulin signaling and glucose transport. All of this occurs within a 4-wk period. Conversely, exercise can rapidly improve insulin response, in as little as one exercise bout. Thus, if the early development of leptin resistance is a contributor to HF diet-induced insulin resistance (IR) in skeletal muscle, then it is logical to predict that the rapid restoration of insulin response by exercise training would be preceded by the recovery of leptin response. In the current study, we sought to determine 1) whether 1, 2, or 4 wk of exercise training was sufficient to restore leptin response in isolated soleus muscle of rats already consuming a HF diet (60% kcal), and 2) whether this preceded the training-induced corrections in FA metabolism and improved insulin-stimulated glucose transport. In the low-fat (LF)-fed control group, insulin increased glucose transport by 153% and leptin increased AMPK and ACC phosphorylation and the rate of palmitate oxidation (+73%). These responses to insulin and leptin were either severely blunted or absent following 4 wk of HF feeding. Exercise intervention decreased muscle ceramide content (-28%) and restored insulin-stimulated glucose transport to control levels within 1 wk; muscle leptin response (AMPK and ACC phosphorylation, FA oxidation) was also restored, but not until the 2-wk time point. In conclusion, endurance exercise training is able to restore leptin response, but this does not appear to be a necessary precursor for the restoration of insulin response.
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Affiliation(s)
- Ian R W Ritchie
- Dept. of Human Health and Nutritional Sciences, Animal Science and Nutrition Bldg., Rm 205, University of Guelph, Guelph, ON, Canada
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