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The Influence of Physical Activity on the Bioactive Lipids Metabolism in Obesity-Induced Muscle Insulin Resistance. Biomolecules 2020; 10:biom10121665. [PMID: 33322719 PMCID: PMC7764345 DOI: 10.3390/biom10121665] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/08/2020] [Accepted: 12/11/2020] [Indexed: 12/14/2022] Open
Abstract
High-fat diet consumption and lack of physical activity are important risk factors for metabolic disorders such as insulin resistance and cardiovascular diseases. Insulin resistance is a state of a weakened response of tissues such as skeletal muscle, adipose tissue, and liver to insulin, which causes an increase in blood glucose levels. This condition is the result of inhibition of the intracellular insulin signaling pathway. Skeletal muscle is an important insulin-sensitive tissue that accounts for about 80% of insulin-dependent glucose uptake. Although the exact mechanism by which insulin resistance is induced has not been thoroughly understood, it is known that insulin resistance is most commonly associated with obesity. Therefore, it is believed that lipids may play an important role in inducing insulin resistance. Among lipids, researchers’ attention is mainly focused on biologically active lipids: diacylglycerols (DAG) and ceramides. These lipids are able to regulate the activity of intracellular enzymes, including those involved in insulin signaling. Available data indicate that physical activity affects lipid metabolism and has a positive effect on insulin sensitivity in skeletal muscles. In this review, we have presented the current state of knowledge about the impact of physical activity on insulin resistance and metabolism of biologically active lipids.
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Musial B, Fernandez‐Twinn DS, Duque‐Guimaraes D, Carr SK, Fowden AL, Ozanne SE, Sferruzzi‐Perri AN. Exercise alters the molecular pathways of insulin signaling and lipid handling in maternal tissues of obese pregnant mice. Physiol Rep 2019; 7:e14202. [PMID: 31466137 PMCID: PMC6715452 DOI: 10.14814/phy2.14202] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 07/24/2019] [Accepted: 07/25/2019] [Indexed: 02/02/2023] Open
Abstract
Obesity during gestation adversely affects maternal and infant health both during pregnancy and for long afterwards. However, recent work suggests that a period of maternal exercise during pregnancy can improve metabolic health of the obese mother and her offspring. This study aimed to identify the physiological and molecular impact of exercise on the obese mother during pregnancy that may lead to improved metabolic outcomes. To achieve this, a 20-min treadmill exercise intervention was performed 5 days a week in diet-induced obese female mice from 1 week before and up to day 17 of pregnancy. Biometric, biochemical and molecular analyses of maternal tissues and/or plasma were performed on day 19 of pregnancy. We found exercise prevented some of the adverse changes in insulin signaling and lipid metabolic pathways seen in the liver, skeletal muscle and white adipose tissue of sedentary-obese pregnant dams (p110β, p110α, AKT, SREBP). Exercise also induced changes in the insulin and lipid signaling pathways in obese dams that were different from those observed in control and sedentary-obese dams. The changes induced by obesity and exercise were tissue-specific and related to alterations in tissue lipid, protein and glycogen content and plasma insulin, leptin and triglyceride concentrations. We conclude that the beneficial effects of exercise on metabolic outcomes in obese mothers may be related to specific molecular signatures in metabolically active maternal tissues during pregnancy. These findings highlight potential metabolic targets for therapeutic intervention and the importance of lifestyle in reducing the burden of the current obesity epidemic on healthcare systems.
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Affiliation(s)
- Barbara Musial
- Centre for Trophoblast Research, Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUnited Kingdom
| | - Denise S. Fernandez‐Twinn
- MRC Metabolic Disease UnitUniversity of Cambridge Metabolic Research Laboratories, Wellcome Trust‐MRC Institute of Metabolic Science, Addenbrooke’s HospitalCambridgeUnited Kingdom
| | - Daniella Duque‐Guimaraes
- MRC Metabolic Disease UnitUniversity of Cambridge Metabolic Research Laboratories, Wellcome Trust‐MRC Institute of Metabolic Science, Addenbrooke’s HospitalCambridgeUnited Kingdom
| | - Sarah K. Carr
- MRC Metabolic Disease UnitUniversity of Cambridge Metabolic Research Laboratories, Wellcome Trust‐MRC Institute of Metabolic Science, Addenbrooke’s HospitalCambridgeUnited Kingdom
| | - Abigail L. Fowden
- Centre for Trophoblast Research, Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUnited Kingdom
| | - Susan E. Ozanne
- MRC Metabolic Disease UnitUniversity of Cambridge Metabolic Research Laboratories, Wellcome Trust‐MRC Institute of Metabolic Science, Addenbrooke’s HospitalCambridgeUnited Kingdom
| | - Amanda N. Sferruzzi‐Perri
- Centre for Trophoblast Research, Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUnited Kingdom
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Møller LLV, Klip A, Sylow L. Rho GTPases-Emerging Regulators of Glucose Homeostasis and Metabolic Health. Cells 2019; 8:E434. [PMID: 31075957 PMCID: PMC6562660 DOI: 10.3390/cells8050434] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/02/2019] [Accepted: 05/06/2019] [Indexed: 12/11/2022] Open
Abstract
Rho guanosine triphosphatases (GTPases) are key regulators in a number of cellular functions, including actin cytoskeleton remodeling and vesicle traffic. Traditionally, Rho GTPases are studied because of their function in cell migration and cancer, while their roles in metabolism are less documented. However, emerging evidence implicates Rho GTPases as regulators of processes of crucial importance for maintaining metabolic homeostasis. Thus, the time is now ripe for reviewing Rho GTPases in the context of metabolic health. Rho GTPase-mediated key processes include the release of insulin from pancreatic β cells, glucose uptake into skeletal muscle and adipose tissue, and muscle mass regulation. Through the current review, we cast light on the important roles of Rho GTPases in skeletal muscle, adipose tissue, and the pancreas and discuss the proposed mechanisms by which Rho GTPases act to regulate glucose metabolism in health and disease. We also describe challenges and goals for future research.
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Affiliation(s)
- Lisbeth Liliendal Valbjørn Møller
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100 Copenhagen Oe, Denmark.
| | - Amira Klip
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada.
| | - Lykke Sylow
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100 Copenhagen Oe, Denmark.
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A genome-wide scan for diversifying selection signatures in selected horse breeds. PLoS One 2019; 14:e0210751. [PMID: 30699152 PMCID: PMC6353161 DOI: 10.1371/journal.pone.0210751] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 12/30/2018] [Indexed: 12/20/2022] Open
Abstract
The genetic differentiation of the current horse population was evolutionarily created by natural or artificial selection which shaped the genomes of individual breeds in several unique ways. The availability of high throughput genotyping methods created the opportunity to study this genetic variation on a genome-wide level allowing detection of genome regions divergently selected between separate breeds as well as among different horse types sharing similar phenotypic features. In this study, we used the population differentiation index (FST) that is generally used for measuring locus-specific allele frequencies variation between populations, to detect selection signatures among six horse breeds maintained in Poland. These breeds can be classified into three major categories, including light, draft and primitive horses, selected mainly in terms of type (utility), exterior, performance, size, coat color and appearance. The analysis of the most pronounced selection signals found in this study allowed us to detect several genomic regions and genes connected with processes potentially important for breed phenotypic differentiation and associated with energy homeostasis during physical effort, heart functioning, fertility, disease resistance and motor coordination. Our results also confirmed previously described association of loci on ECA3 (spanning LCORL and NCAPG genes) and ECA11 (spanning LASP1 gene) with the regulation of body size in our draft and primitive (small size) horses. The efficiency of the applied FST-based approach was also confirmed by the identification of a robust selection signal in the blue dun colored Polish Konik horses at the locus of TBX3 gene, which was previously shown to be responsible for dun coat color dilution in other horse breeds. FST-based method showed to be efficient in detection of diversifying selection signatures in the analyzed horse breeds. Especially pronounced signals were observed at the loci responsible for fixed breed-specific features. Several candidate genes under selection were proposed in this study for traits selected in separate breeds and horse types, however, further functional and comparative studies are needed to confirm and explain their effect on the observed genetic diversity of the horse breeds.
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Li G, Zhang T, Zhang G, Chen L, Han W, Guojun Dai, Xie K, Zhu X, Su Y, Wang J. Analysis of gene co-expression networks and function modules at different developmental stages of chicken breast muscle. Biochem Biophys Res Commun 2019; 508:177-183. [PMID: 30471858 DOI: 10.1016/j.bbrc.2018.11.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 11/07/2018] [Indexed: 11/17/2022]
Abstract
The development of poultry muscle fibers after hatching is closely related to meat quality and production efficiency. It is necessary to identify functional modules (groups of functionally related genes) related to muscle development at different developmental stages, and to investigate their relationships based on the weighted gene co-expression network analysis (WGCNA) methods. Accordingly, we investigated the co-expression associations between genes related to chicken breast muscle at four different developmental stages (between 2 and 14 weeks of age), and systematically analyzed the network topology in Jinmao Hua chicken. As a result, 2341 differentially expressed genes were identified and subjected to co-expression analysis. Four modules were identified to be related to a particular growth stage for the development of breast muscle. A series of genes with the highest connectivity were identified in the pink (2 weeks), yellow (6 weeks), green (10 weeks) and black modules (14 weeks), respectively, and visualized by Cytoscape. These hub genes (FGF, MAPKAPK5, NRG1, SCD, ACSL1, PPAR etc.) were mainly enriched in 15 pathways, such as MAPK signaling pathway, NRG/ErbB signaling pathway, and insulin signaling pathway. They shared biological functions related to development of breast muscle and adipogenesis. This is the first study of gene network with different stages of muscle development in Jinmao Hua chicken to observe co-expression patterns. It may contribute to the underlied molecular mechanisms of chicken breast muscle development.
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Affiliation(s)
- Guohui Li
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, 225009, China; Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, Jiangsu, 225125, China.
| | - Tao Zhang
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, 225009, China; International Cooperation Laboratory of Agriculture and Agriculture Products Safety, Yangzhou, Jiangsu, 225009, China
| | - Genxi Zhang
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, 225009, China; International Cooperation Laboratory of Agriculture and Agriculture Products Safety, Yangzhou, Jiangsu, 225009, China
| | - Lan Chen
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, 225009, China; International Cooperation Laboratory of Agriculture and Agriculture Products Safety, Yangzhou, Jiangsu, 225009, China
| | - Wei Han
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, Jiangsu, 225125, China
| | - Guojun Dai
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, 225009, China
| | - Kaizhou Xie
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, 225009, China; International Cooperation Laboratory of Agriculture and Agriculture Products Safety, Yangzhou, Jiangsu, 225009, China
| | - Xiaoyan Zhu
- Jiangsu Sandeli Animal Husbandry Development Co.,Ltd, Jintan, Jiangsu, 221000, China
| | - Yijun Su
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, Jiangsu, 225125, China
| | - Jinyu Wang
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, 225009, China.
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Ropka-Molik K, Stefaniuk-Szmukier M, Żukowski K, Piórkowska K, Gurgul A, Bugno-Poniewierska M. Transcriptome profiling of Arabian horse blood during training regimens. BMC Genet 2017; 18:31. [PMID: 28381206 PMCID: PMC5382464 DOI: 10.1186/s12863-017-0499-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 03/30/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Arabian horses are believed to be one of the oldest and most influential horse breeds in the world. Blood is the main tissue involved in maintaining body homeostasis, and it is considered a marker of the processes taking place in the other tissues. Thus, the aim of our study was to identify the genetic basis of changes occurring in the blood of Arabian horses subjected to a training regimen and to compare the global gene expression profiles between different training periods (T1: after a slow canter phase that is considered a conditioning phase, T2: after an intense gallop phase, and T3: at the end of the racing season) and between trained and untrained horses (T0). RNA sequencing was performed on 37 samples with a 75-bp single-end run on a HiScanSQ platform (Illumina), and differentially expressed genes (DEGs) were identified based on DESeq2 (v1.11.25) software. RESULTS An increase in the number of DEGs between subsequent training periods was observed, and the highest amount of DEGs (440) was detected between untrained horses (T0) and horses at the end of the racing season (T3). The comparisons of the T2 vs. T3 transcriptomes and the T0 vs. T3 transcriptomes showed a significant gain of up-regulated genes during long-term exercise (up-regulation of 266 and 389 DEGs in the T3 period compared to T2 and T0, respectively). Forty differentially expressed genes were detected between the T1 and T2 periods, and 296 between T2 and T3. Functional annotation showed that the most abundant genes up-regulated in exercise were involved in pathways regulating cell cycle (PI3K-Akt signalling pathway), cell communication (cAMP-dependent pathway), proliferation, differentiation and apoptosis, as well as immunity processes (Jak-STAT signalling pathway). CONCLUSIONS We investigated whether training causes permanent transcriptome changes in horse blood as a reflection of adaptation to conditioning and the maintenance of fitness to compete in flat races. The present study identified the overrepresented molecular pathways and genes that are essential for maintaining body homeostasis during long-term exercise in Arabian horses. Selected DEGs should be further investigated as markers that are potentially associated with racing performance in Arabian horses.
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Affiliation(s)
- Katarzyna Ropka-Molik
- Department of Genomics and Animal Molecular Biology, National Research Institute of Animal Production, Balice, Poland.
| | - Monika Stefaniuk-Szmukier
- Department of Horse Breeding, Institute of Animal Science, University of Agriculture in Cracow, Kracow, Poland
| | - Kacper Żukowski
- Department of Animal Genetics and Breeding, National Research Institute of Animal Production, Balice, Poland
| | - Katarzyna Piórkowska
- Department of Genomics and Animal Molecular Biology, National Research Institute of Animal Production, Balice, Poland
| | - Artur Gurgul
- Department of Genomics and Animal Molecular Biology, National Research Institute of Animal Production, Balice, Poland
| | - Monika Bugno-Poniewierska
- Department of Genomics and Animal Molecular Biology, National Research Institute of Animal Production, Balice, Poland
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Tashiro A, Shibata S, Takai Y, Uchiwa T, Furuse M, Yasuo S. Changes in photoperiod alter Glut4 expression in skeletal muscle of C57BL/6J mice. Biochem Biophys Res Commun 2017; 485:82-88. [DOI: 10.1016/j.bbrc.2017.02.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 02/05/2017] [Indexed: 12/14/2022]
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Santos VC, Sierra APR, Oliveira R, Caçula KG, Momesso CM, Sato FT, Silva MBB, Oliveira HH, Passos MEP, de Souza DR, Gondim OS, Benetti M, Levada-Pires AC, Ghorayeb N, Kiss MAPDM, Gorjão R, Pithon-Curi TC, Cury-Boaventura MF. Marathon Race Affects Neutrophil Surface Molecules: Role of Inflammatory Mediators. PLoS One 2016; 11:e0166687. [PMID: 27911915 PMCID: PMC5135050 DOI: 10.1371/journal.pone.0166687] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 11/02/2016] [Indexed: 02/06/2023] Open
Abstract
The fatigue induced by marathon races was observed in terms of inflammatory and immunological outcomes. Neutrophil survival and activation are essential for inflammation resolution and contributes directly to the pathogenesis of many infectious and inflammatory conditions. The aim of this study was to investigate the effect of marathon races on surface molecules related to neutrophil adhesion and extrinsic apoptosis pathway and its association with inflammatory markers. We evaluated 23 trained male runners at the São Paulo International Marathon 2013. The following components were measured: hematological and inflammatory mediators, muscle damage markers, and neutrophil function. The marathon race induced an increased leukocyte and neutrophil counts; creatine kinase (CK), lactate dehydrogenase (LDH), CK-MB, interleukin (IL)-6, IL-10, and IL-8 levels. C-reactive protein (CRP), IL-12, and tumor necrosis factor (TNF)-α plasma concentrations were significantly higher 24 h and 72 h after the marathon race. Hemoglobin and hematocrit levels decreased 72 h after the marathon race. We also observed an increased intercellular adhesion molecule-1 (ICAM-1) expression and decreasedTNF receptor-1 (TNFR1) expression immediately after and 24 h after the marathon race. We observed an increased DNA fragmentation and L-selectin and Fas receptor expressions in the recovery period, indicating a possible slow rolling phase and delayed neutrophil activation and apoptosis. Marathon racing affects neutrophils adhesion and survival in the course of inflammation, supporting the “open-window” post-exercise hypothesis.
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Affiliation(s)
- Vinicius Coneglian Santos
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, Brazil
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
| | - Ana Paula Renno Sierra
- School of Physical Education and Sport, University of São Paulo, São Paulo, São Paulo, Brazil
- Sports Cardiology Department, Dante Pazzanese Institute of Cardiology, São Paulo, São Paulo, Brazil
- Medicine Department, Nove de Julho University, São Paulo, São Paulo, Brazil
- * E-mail: (MFCB); (APRS)
| | - Rodrigo Oliveira
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
| | - Kim Guimarães Caçula
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
| | - César Miguel Momesso
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
| | - Fabio Takeo Sato
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, Brazil
| | - Maysa Braga Barros Silva
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
| | - Heloisa Helena Oliveira
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
| | | | - Diego Ribeiro de Souza
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
| | - Olivia Santos Gondim
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
| | - Marino Benetti
- School of Physical Education and Sport, University of São Paulo, São Paulo, São Paulo, Brazil
| | | | - Nabil Ghorayeb
- Sports Cardiology Department, Dante Pazzanese Institute of Cardiology, São Paulo, São Paulo, Brazil
| | | | - Renata Gorjão
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
| | - Tânia Cristina Pithon-Curi
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, Brazil
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
| | - Maria Fernanda Cury-Boaventura
- Institute of Physical Activity and Sports Sciences, University of Cruzeiro do Sul, São Paulo, São Paulo, Brazil
- * E-mail: (MFCB); (APRS)
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Regular thermal therapy may promote insulin sensitivity while boosting expression of endothelial nitric oxide synthase--effects comparable to those of exercise training. Med Hypotheses 2009; 73:103-5. [PMID: 19203842 DOI: 10.1016/j.mehy.2008.12.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Accepted: 12/15/2008] [Indexed: 11/20/2022]
Abstract
Regular thermal therapy, using saunas or hot baths, has the potential to improve impaired insulin sensitivity and boost endothelial expression of the "constitutive" isoform of nitric oxide synthase--effects, analogous to those of aerobic training that should promote vascular health. Previous clinical reports suggest that hot tubs may be beneficial for diabetic control, and that sauna therapy can decrease blood pressure in essential hypertension and provide symptomatic benefit in congestive heart failure. For those who lack ready access to a sauna or communal hot tub, regular hot baths at home may suffice as practical thermal therapy. Thermal therapy might be viewed as an alternative to exercise training in patients too physically impaired for significant aerobic activity.
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Abstract
Individuals with insulin resistance are characterized by impaired insulin action on whole-body glucose uptake, in part due to impaired insulin-stimulated glucose uptake into skeletal muscle. A single bout of exercise increases skeletal muscle glucose uptake via an insulin-independent mechanism that bypasses the typical insulin signalling defects associated with these conditions. However, this 'insulin sensitizing' effect is short-lived and disappears after approximately 48 h. In contrast, repeated physical activity (i.e. exercise training) results in a persistent increase in insulin action in skeletal muscle from obese and insulin-resistant individuals. The molecular mechanism(s) for the enhanced glucose uptake with exercise training have been attributed to the increased expression and/or activity of key signalling proteins involved in the regulation of glucose uptake and metabolism in skeletal muscle. Evidence now suggests that the improvements in insulin sensitivity associated with exercise training are also related to changes in the expression and/or activity of proteins involved in insulin signal transduction in skeletal muscle such as the AMP-activated protein kinase (AMPK) and the protein kinase B (Akt) substrate AS160. In addition, increased lipid oxidation and/or turnover is likely to be another mechanism by which exercise improves insulin sensitivity: exercise training results in an increase in the oxidative capacity of skeletal muscle by up-regulating lipid oxidation and the expression of proteins involved in mitochondrial biogenesis. Determination of the underlying biological mechanisms that result from exercise training is essential in order to define the precise variations in physical activity that result in the most desired effects on targeted risk factors, and to aid in the development of such interventions.
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Affiliation(s)
- J A Hawley
- Exercise Metabolism Group, School of Medical Sciences, RMIT University, Bundoora, Vic., Australia.
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Bakos J, Hlavacova N, Makatsori A, Tybitanclova K, Zorad S, Hinghofer-Szalkay H, Johansson BB, Jezova D. Oxytocin levels in the posterior pituitary and in the heart are modified by voluntary wheel running. ACTA ACUST UNITED AC 2006; 139:96-101. [PMID: 17140677 DOI: 10.1016/j.regpep.2006.10.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2006] [Revised: 10/09/2006] [Accepted: 10/18/2006] [Indexed: 01/09/2023]
Abstract
We hypothesized that voluntary wheel running results in increased secretion of oxytocin, a peptide involved in the stress response. An additional hypothesis was that prolonged exercise affects oxytocin levels in the heart, which is in line with the potential role of oxytocin in cardiovascular functions. Voluntary wheel running lasted 3 weeks and daily running distances increased progressively reaching maximum levels about 8 km (Sprague-Dawley rats) and 4 km (Lewis strain). The exercise resulted in significant reduction of epididymal fat, slight increase in glucose transporter GLUT4 mRNA levels and significant enhancement of plasma density. Voluntary exercise failed to influence plasma oxytocin levels either in Lewis or Sprague-Dawley rats, but it resulted in a significant decrease of oxytocin concentrations in the posterior pituitary. Plasma oxytocin concentrations were not modified even if the measurements were made in the dark phase of the day. In voluntary wheel running Sprague-Dawley rats, the content of oxytocin in the right heart atrium was lower than in controls. Thus, the present findings demonstrate that prolonged voluntary wheel running results in a decrease in pituitary oxytocin content without evident changes in hormone concentrations in peripheral blood. However, prolonged exercise used has a significant impact on oxytocin levels in the heart.
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Affiliation(s)
- J Bakos
- Laboratory of Pharmacological Neuroendocrinology, Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlarska 3, Bratislava 83306, Slovakia
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Lemieux AM, Diehl CJ, Sloniger JA, Henriksen EJ. Voluntary exercise training enhances glucose transport but not insulin signaling capacity in muscle of hypertensive TG(mREN2)27 rats. J Appl Physiol (1985) 2005; 99:357-62. [PMID: 15718410 DOI: 10.1152/japplphysiol.00100.2005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Male heterozygous TG(mREN2)27 rats (TGR) overexpress a murine renin transgene, display marked hypertension, and have insulin resistance of skeletal muscle glucose transport and insulin signaling. We have shown previously that voluntary exercise training by TGR improves insulin-mediated skeletal muscle glucose transport (Kinnick TR, Youngblood EB, O’Keefe MP, Saengsirisuwan V, Teachey MK, and Henriksen EJ. J Appl Physiol 93: 805–812, 2002). The present study evaluated whether this training-induced enhancement of muscle glucose transport is associated with upregulation of critical insulin signaling elements, including insulin receptor substrate-1 (IRS-1), phosphatidylinositol 3-kinase, Akt, and glycogen synthase kinase-3. TGR remained sedentary or ran spontaneously in activity wheels for 6 wk, averaging 7.1 ± 0.8 km/day by the end of week 3 and 4.3 ± 0.5 km/day over the final week of training. Exercise training reduced total abdominal fat by 20% ( P < 0.05) in TGR runners (2.64 ± 0.01% of body weight) compared with sedentary TGR controls (3.28 ± 0.01%). Insulin-stimulated (2 mU/ml) glucose transport activity in soleus muscle was 36% greater in TGR runners compared with sedentary TGR controls. However, the protein expression and functionality of tyrosine phosphorylation of insulin receptor and IRS-1, IRS-1 associated with the p85 regulatory subunit of phosphatidylinositol 3-kinase, and Ser473 phosphorylation of Akt were not altered by exercise training. Only insulin-stimulated glycogen synthase kinase-3β Ser9 phosphorylation was increased (22%) by exercise training. These results indicate that voluntary exercise training in TGR can enhance insulin-mediated glucose transport in skeletal muscle, as well as reduce total abdominal fat mass. However, this adaptive response in muscle occurs independently of modifications in the proximal elements of the insulin signaling cascade.
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Affiliation(s)
- Andrew M Lemieux
- Dept. of Physiology, Univ. of Arizona College of Medicine, Tucson, AZ 85721-0093, USA
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Renström F, Burén J, Eriksson JW. Insulin receptor substrates-1 and -2 are both depleted but via different mechanisms after down-regulation of glucose transport in rat adipocytes. Endocrinology 2005; 146:3044-51. [PMID: 15845625 DOI: 10.1210/en.2004-1675] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Alterations in muscle and adipose tissue insulin receptor substrate (IRS)-1 and IRS-2 are associated with, and commonly believed to contribute to, development of insulin resistance. In this study, we investigated the mechanisms behind previously observed reductions in IRS levels due to high concentrations of glucose and insulin and their significance in the impairment of glucose uptake capacity in primary rat adipocytes. Semiquantitative RT-PCR analysis showed that insulin (10(4) microU/ml) alone or in combination with glucose (15 mm) markedly suppressed IRS-2 gene expression, whereas IRS-1 mRNA was unaffected by the culture conditions. The negative effect of a high glucose/high insulin setting on IRS-1 protein level was still exerted when protein synthesis was inhibited with cycloheximide. Impairment of glucose uptake capacity after treatment with high glucose and insulin was most pronounced after 3 h, whereas IRS-1 and IRS-2 protein levels were unaffected up to 6 h but were reduced after 16 h. Moreover, impaired glucose uptake capacity could only partially be reversed by subsequent incubation at physiological conditions. These novel results suggest that: 1) in a high glucose/high insulin setting depletion of IRS-1 and IRS-2 protein, respectively, occurs via different mechanisms, and IRS-2 gene expression is suppressed, whereas IRS-1 depletion is due to posttranslational mechanisms; 2) IRS-1 and IRS-2 protein depletion is a secondary event in the development of insulin resistance in this model of hyperglycemia/hyperinsulinemia; and 3) depletion of cellular IRS in adipose tissue may be a consequence rather than a cause of insulin resistance and hyperinsulinemia in type 2 diabetes.
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Affiliation(s)
- Frida Renström
- Department of Medicine, Umeå University Hospital, SE-901 85 Umeå, Sweden
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Bernard JR, Crain AM, Rivas DA, Herr HJ, Reeder DW, Yaspelkis BB. Chronic aerobic exercise enhances components of the classical and novel insulin signalling cascades in Sprague-Dawley rat skeletal muscle. ACTA ACUST UNITED AC 2005; 183:357-66. [PMID: 15799772 DOI: 10.1111/j.1365-201x.2005.01408.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
AIM The aim of this study was to provide a more extensive evaluation of the effects of chronic aerobic exercise on various components of the insulin signalling cascade in normal rodent skeletal muscle because of the limited body of literature that exists in this area of investigation. METHODS Male Sprague-Dawley rats were assigned to either control (n = 7) or chronic aerobic exercise (n = 7) groups. Aerobic exercise animals were run 3 day week(1) for 45 min on a motor-driven treadmill (32 m min(1), 15% grade) for a 12 week period. Following the training period, all animals were subjected to hind limb perfusion in the presence of 500 microU mL(1) insulin to determine what effect chronic aerobic training had on various components of the insulin signalling cascade, c-Cbl protein concentration and c-Cbl phosphorylation. RESULTS Twelve weeks of aerobic training did not alter skeletal muscle Akt 1/2 protein concentration, Akt Ser 473 phosphorylation, Akt Thr 308 phosphorylation, Akt 1 activity, aPKC-zeta protein concentration, aPKC-lambda protein concentration or c-Cbl protein concentration. In contrast, chronic aerobic exercise increased insulin-stimulated phosphatidylinositol 3-kinase, Akt 2 kinase and aPKC-zeta/lambda kinase activities, as well as c-Cbl tyrosine phosphorylation, in a fibre type specific response to aerobic training. In addition, chronic aerobic exercise enhanced insulin-stimulated plasma membrane glucose transporter 4 (GLUT4) protein concentration. CONCLUSION Collectively, these findings suggest that chronic aerobic exercise enhances components of both the classical and novel insulin signalling cascades in normal rodent skeletal muscle, which may contribute to an increased insulin-stimulated plasma membrane GLUT4 protein concentration.
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Affiliation(s)
- J R Bernard
- Exercise Biochemistry Laboratory, Department of Kinesiology, College of Health and Human Development, California State University Northridge, 91330-8287, USA
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15
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Abstract
Sedentary death syndrome (SeDS) is a major public health burden due to its causing multiple chronic diseases and millions of premature deaths each year. Despite the impact of physical inactivity, very little is known about the actual causes of physical inactivity-induced chronic diseases. It is important to study the mechanisms underlying molecular changes related to physical inactivity in order to better understand the scientific basis of individualized exercise prescription and therapies for chronic diseases, and to support improved public health efforts by providing molecular proof that physical inactivity is an actual cause of chronic diseases. Physical activity has a genetic basis. A subpopulation of genes, which have functioned to support physical activity for survival through most of humankind's existence, require daily exercise to maintain long-term health and vitality. Type 2 diabetes (T2D) is an example of a SeDS condition, as it is almost entirely preventable with physical activity. To determine the true role of physical inactivity in the development and progression of T2D, information is presented which indicates that comparisons should be made to physically active controls, rather than sedentary controls, as this population is the healthiest. Use of sedentary subjects as the control group has led to potentially misleading interpretations. If physically active individuals were designated as the control group, a different interpretation would have been drawn. It is thought that there is no difference in GLUT4 concentration between T2D and sedentary groups. However, GLUT4 expression is higher in active controls than in sedentary and T2D groups. Therefore, to obtain causal mechanisms for SeDS in order to allow for scientifically based prevention and therapy strategies, physically active subjects must serve as the control group.
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Affiliation(s)
- Simon J Lees
- Dept. of Biomedical Sciences, Univ. of Missouri-Columbia, Columbia, MO, USA
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16
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Matsakas A, Friedel A, Hertrampf T, Diel P. Short-term endurance training results in a muscle-specific decrease of myostatin mRNA content in the rat. ACTA ACUST UNITED AC 2005; 183:299-307. [PMID: 15743390 DOI: 10.1111/j.1365-201x.2005.01406.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIM Myostatin has been characterized as a negative regulator of skeletal muscle growth. To examine a probable function of myostatin during the adaptation of skeletal muscle in response to training, we analysed the effect of short-term endurance training on myostatin and insulin-like growth factor-I (IGF-I) mRNA contents in rat skeletal muscles. To assess the impact of the training stimulus, mRNA levels of metabolic genes were analysed simultaneously. METHODS Male Wistar rats were trained for 5 days by swimming, while another group remained untrained. Myostatin, IGF-I, glucose transporter 4 (GLUT4), hexokinase II (HK II) and hydroxyacyl-CoA dehydrogenase (HAD) mRNA levels were determined by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) in gastrocnemius, vastus lateralis and soleus muscles. A time course experiment was conducted, in order to examine transient changes of myostatin mRNA contents in gastrocnemius 7 and 24 h after one-swimming session as well as 24 h after a 3-day swimming training. RESULTS No significant changes in IGF-I and GLUT4 mRNA levels were found in any of the muscles analysed. mRNA contents of myostatin were significantly reduced in gastrocnemius and vastus lateralis but not in soleus. In agreement to this pattern, we found significantly higher mRNA levels of HK II and HAD in the trained group. The time course experiment revealed significantly reduced myostatin mRNA contents in gastrocnemius 7 but not 24 h post-exercise. The 3-day swimming training resulted also in significantly lower myostatin mRNA levels in the trained group. CONCLUSION This study demonstrated that short-term endurance training may modulate myostatin mRNA levels, implying a probable role of myostatin in remodelling of skeletal muscle in response to training.
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Affiliation(s)
- A Matsakas
- Department of Molecular and Cellular Sports Medicine, German Sport University Cologne, Carl-Diem-Weg 6, 50933 Cologne, Germany
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Holmes BF, Lang DB, Birnbaum MJ, Mu J, Dohm GL. AMP kinase is not required for the GLUT4 response to exercise and denervation in skeletal muscle. Am J Physiol Endocrinol Metab 2004; 287:E739-43. [PMID: 15165992 DOI: 10.1152/ajpendo.00080.2004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
An acute bout of exercise increases muscle GLUT4 mRNA in mice, and denervation decreases GLUT4 mRNA. AMP-activated protein kinase (AMPK) activity in skeletal muscle is also increased by exercise, and GLUT4 mRNA is increased in mouse skeletal muscle after treatment with AMPK activator 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside(AICAR). These findings suggest that AMPK activation might be responsible for the increase in GLUT4 mRNA expression in response to exercise. To investigate the role of AMPK in GLUT4 regulation in response to exercise and denervation, transgenic mice with a mutated AMPK alpha-subunit (dominant negative; AMPK-DN) were studied. GLUT4 did not increase in AMPK-DN mice that were treated with AICAR, demonstrating that muscle AMPK is inactive. Exercise (two 3-h bouts of treadmill running separated by 1 h of rest) increased GLUT4 mRNA in both wild-type and AMPK-DN mice. Likewise, denervation decreased GLUT4 mRNA in both wild-type and AMPK-DN mice. GLUT4 mRNA was also increased by AICAR treatment in both the innervated and denervated muscles. These data demonstrate that AMPK is not required for the response of GLUT4 mRNA to exercise and denervation.
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Christ-Roberts CY, Pratipanawatr T, Pratipanawatr W, Berria R, Belfort R, Kashyap S, Mandarino LJ. Exercise training increases glycogen synthase activity and GLUT4 expression but not insulin signaling in overweight nondiabetic and type 2 diabetic subjects. Metabolism 2004; 53:1233-42. [PMID: 15334390 DOI: 10.1016/j.metabol.2004.03.022] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Exercise training improves insulin sensitivity in subjects with and without type 2 diabetes. However, the mechanism by which this occurs is unclear. The present study was undertaken to determine how improved insulin signaling, GLUT4 expression, and glycogen synthase activity contribute to this improvement. Euglycemic clamps with indirect calorimetry and muscle biopsies were performed before and after 8 weeks of exercise training in 16 insulin-resistant nondiabetic subjects and 6 type 2 diabetic patients. Training increased peak aerobic capacity (Vo(2peak)) in both nondiabetic (from 34 +/- 2 to 39 +/- 2 mL O(2)/kg fat-free mass [FFM]/min, 14% +/- 2%, P <.001) and diabetic (from 26 +/- 3 to 34 +/- 3 mL O(2)/kg FFM/min, 32% +/- 4%) subjects. Training also increased insulin-stimulated glucose disposal in nondiabetic (from 6.2 +/- 0.5 to 7.1 +/- 0.7 mg/kg FFM/min) and diabetic subjects (from 4.3 +/- 0.6 to 5.5 +/- 0.6 mg/kg FFM/min). Total glycogen synthase activity was increased by 46% +/- 17% and 45% +/- 12% in nondiabetic and diabetic subjects, respectively, in response to training (P <.01 v before training). Moreover, after training, glycogen synthase fractional velocity was correlated with insulin-stimulated glucose storage (r = 0.53, P <.05) and the training-induced improvement in glucose disposal was accounted for primarily by increased insulin-stimulated glucose storage. Training also increased GLUT4 protein by 38% +/- 8% and 22% +/- 10% in nondiabetic and diabetic subjects, respectively (P <.05 v. before training). Akt protein expression, which was decreased by 29% +/- 3% (P <.05) in the diabetic subjects before training (compared to the nondiabetics), increased significantly in both groups (P <.001). In contrast, exercise training did not enhance the ability of insulin to stimulate insulin receptor substrate-1 (IRS-1)-associated phosphatidylinositol 3 (PI 3)-kinase activity. The present data are consistent with a working model whereby 8 weeks of exercise training increases insulin-stimulated glucose disposal primarily by increasing GLUT4 protein expression without enhancing insulin-stimulated PI 3-kinase signaling, and that once the glucose enters the myocyte, increased glycogen synthase activity preferentially shunts it into glycogen synthesis.
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19
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van Dam KG, van Breda E, Schaart G, van Ginneken MME, Wijnberg ID, de Graaf-Roelfsema E, van der Kolk JH, Keizer HA. Investigation of the expression and localization of glucose transporter 4 and fatty acid translocase/CD36 in equine skeletal muscle. Am J Vet Res 2004; 65:951-6. [PMID: 15281654 DOI: 10.2460/ajvr.2004.65.951] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate the expression and localization of glucose transporter 4 (GLUT4) and fatty acid translocase (FAT/CD36) in equine skeletal muscle. SAMPLE POPULATION Muscle biopsy specimens obtained from 5 healthy Dutch Warmblood horses. PROCEDURES Percutaneous biopsy specimens were obtained from the vastus lateralis, pectoralis descendens, and triceps brachii muscles. Cryosections were stained with combinations of GLUT4 and myosin heavy chain (MHC) specific antibodies or FAT/CD36 and MHC antibodies to assess the fiber specific expression of GLUT4 and FAT/CD36 in equine skeletal muscle via indirect immunofluorescent microscopy. RESULTS Immunofluorescent staining revealed that GLUT4 was predominantly expressed in the cytosol of fast type 2B fibers of equine skeletal muscle, although several type 1 fibers in the vastus lateralis muscle were positive for GLUT4. In all muscle fibers examined microscopically, FAT/CD36 was strongly expressed in the sarcolemma and capillaries. Type 1 muscle fibers also expressed small intracellular amounts of FAT/CD36, but no intracellular FAT/CD36 expression was detected in type 2 fibers. CONCLUSIONS AND CLINICAL RELEVANCE In equine skeletal muscle, GLUT4 and FAT/CD36 are expressed in a fiber type selective manner.
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Affiliation(s)
- Klien G van Dam
- Department of Equine Sciences (Medicine Section), Faculty of Veterinary Medicine, Utrecht University, Yalelaan 16, NL-3584 CM Utrecht, The Netherlands
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20
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McCarty MF. A wholly nutritional 'multifocal angiostatic therapy' for control of disseminated cancer. Med Hypotheses 2003; 61:1-15. [PMID: 12781633 DOI: 10.1016/s0306-9877(02)00227-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A great deal of effort is now being devoted to the development of new drugs that hopefully will control the spread of inoperable cancer by safely inhibiting tumor-evoked angiogenesis. However, there is growing evidence that certain practical nutritional measures have the potential to slow tumor angiogenesis, and it is reasonable to anticipate that, by combining several measures that work in distinct but complementary ways to impede the angiogenic process, a clinically useful 'multifocal angiostatic therapy' (MAT) might be devised. Several measures which might reasonably be included in such a protocol are discussed below, and include: a low-fat, low-glycemic index vegan diet, which may down-regulate the systemic IGF-I activity that supports angiogenesis; supplemental omega-3-rich fish oil, which has been shown to inhibit endothelial expression of Flk-1, a functionally crucial receptor for VEGF, and also can suppress tumor production of pro-angiogenic eicosanoids; high-dose selenium, which has recently been shown to inhibit tumor production of VEGF; green tea polyphenols, which can suppress endothelial responsiveness to both VEGF and fibroblast growth factor; and high-dose glycine, whose recently reported angiostatic activity may reflect inhibition of endothelial cell mitosis, possibly mediated by activation of glycine-gated chloride channels. In light of evidence that tumor-evoked angiogenesis has a high requirement for copper, copper depletion may have exceptional potential as an angiostatic measure, and is most efficiently achieved with the copper-chelating drug tetrathiomolybdate. If logistical difficulties make it difficult to acquire this experimental drug, high-dose zinc supplementation can achieve a slower depletion of the body's copper pool, and in any case can be used as maintenance therapy to maintain an adequate level of copper depletion. A provisional protocol is offered for a nutritionally based MAT entailing a vegan diet and supplemental intakes of fish oil, selenium, green tea polyphenols, glycine, and zinc. Inasmuch as cox-2 is overexpressed in many cancers, and cAMP can boost tumor production of various angiogenic factors as well as autogenous growth factors, adjunctive use of cox-2-specific NSAIDS may be warranted in some cases.
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Affiliation(s)
- M F McCarty
- Pantox Laboratories, San Diego, California 92129, USA
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21
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Abstract
Evidence from recent publications indicates that repeated exercise may enhance the quality of life of cancer patients. The lack of reported negative effects and the consistency of the observed benefits lead one to conclude that physical exercise may provide a low-risk therapy that can improve patients' capacity to perform activities of daily living and improve their quality of life. Repeated physical activity may attenuate the adverse effects of cancer therapy, prevent or reverse cachexia, and reduce risk for a second cancer through suppression of inflammatory responses or enhancement of insulin sensitivity, rates of protein synthesis, and anti-oxidant and phase II enzyme activities. These results most likely come about through the ability of physical exercise to attenuate a chronic inflammatory signaling process and to transiently activate the mitogen-activated protein kinase, c-Jun NH2-terminal kinase, c-Jun NH2-terminal kinase-mitogen-activated protein kinase, and nuclear factor-kappa B pathways and through its ability to enhance insulin sensitivity. Expanded molecular-based research into these areas may provide new insights into the biological mechanisms associated with cancer rehabilitation and endogenous risk.
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22
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Zierath JR. Invited review: Exercise training-induced changes in insulin signaling in skeletal muscle. J Appl Physiol (1985) 2002; 93:773-81. [PMID: 12133891 DOI: 10.1152/japplphysiol.00126.2002] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
This review will provide insight on the current understanding of the intracellular signaling mechanisms by which exercise training increases glucose metabolism and gene expression in skeletal muscle. Participation in regular exercise programs can have important clinical implications, leading to improved health in insulin-resistant persons. Evidence is emerging that insulin signal transduction at the level of insulin receptor substrates 1 and 2, as well as phosphatidylinositol 3-kinase, is enhanced in skeletal muscle after exercise training. This is clinically relevant because insulin signaling is impaired in skeletal muscle from insulin-resistant Type 2 diabetic and obese humans. The molecular mechanism for enhanced insulin-stimulated glucose uptake after exercise training may be partly related to increased expression and activity of key proteins known to regulate glucose metabolism in skeletal muscle. Exercise also leads to an insulin-independent increase in glucose transport, mediated in part by AMP-activated protein kinase. Changes in protein expression may be related to increased signal transduction through the mitogen-activated protein kinase signaling cascades, a pathway known to regulate transcriptional activity. Understanding the molecular mechanism for the activation of insulin signal transduction pathways after exercise training may provide novel entry points for new strategies to enhance glucose metabolism and for improved health in the general population.
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Affiliation(s)
- Juleen R Zierath
- Department of Clinical Physiology, Karolinska Hospital, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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23
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Henriksen EJ. Invited review: Effects of acute exercise and exercise training on insulin resistance. J Appl Physiol (1985) 2002; 93:788-96. [PMID: 12133893 DOI: 10.1152/japplphysiol.01219.2001] [Citation(s) in RCA: 312] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Insulin resistance of skeletal muscle glucose transport is a key defect in the development of impaired glucose tolerance and Type 2 diabetes. It is well established that both an acute bout of exercise and chronic endurance exercise training can have beneficial effects on insulin action in insulin-resistant states. This review summarizes the present state of knowledge regarding these effects in the obese Zucker rat, a widely used rodent model of obesity-associated insulin resistance, and in insulin-resistant humans with impaired glucose tolerance or Type 2 diabetes. A single bout of prolonged aerobic exercise (30-60 min at approximately 60-70% of maximal oxygen consumption) can significantly lower plasma glucose levels, owing to normal contraction-induced stimulation of GLUT-4 glucose transporter translocation and glucose transport activity in insulin-resistant skeletal muscle. However, little is currently known about the effects of acute exercise on muscle insulin signaling in the postexercise state in insulin-resistant individuals. A well-established adaptive response to exercise training in conditions of insulin resistance is improved glucose tolerance and enhanced skeletal muscle insulin sensitivity of glucose transport. This training-induced enhancement of insulin action is associated with upregulation of specific components of the glucose transport system in insulin-resistant muscle and includes increased protein expression of GLUT-4 and insulin receptor substrate-1. It is clear that further investigations are needed to further elucidate the specific molecular mechanisms underlying the beneficial effects of acute exercise and exercise training on the glucose transport system in insulin-resistant mammalian skeletal muscle.
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Affiliation(s)
- Erik J Henriksen
- Muscle Metabolism Laboratory, Department of Physiology, University of Arizona College of Medicine, Tucson, Arizona 85721-0093, USA.
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24
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McCarty MF. Incorporation of beta cell redifferentiation therapy into a lipoprivic strategy for reversing type 2 diabetes. Med Hypotheses 2002; 58:462-71. [PMID: 12323111 DOI: 10.1054/mehy.2001.1454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Type 2 diabetes (non-insulin-dependent diabetes mellitus, NIDDM), at least in the majority of patients characterized by insulin resistance and increased visceral fat, appears to be precipitated by the exposure of tissues to excessive levels of free fatty acids; this can contribute to the muscle insulin resistance, excessive hepatic gluconeogenesis, and beta cell dysfunction that collaborate to impair glycemic control. The resultant hyperglycemia, in turn, exacerbates the insulin resistance and beta cells dysfunction. The failure of glucose-stimulated insulin secretion (GSIS) in beta cells helps to sustain the elevations of serum glucose and free fatty acids, which in turn reinforce the failure of GSIS, possibly by inhibiting expression of the transcription factor IDX-1; NIDDM thus represents a vicious cycle that is not easily broken. A new strategy for achieving rapid loss of body fat - hepatothermic therapy (HT), an integrated approach involving exercise training, low-fat, low-glycemic-index food choices, and a supplementation program that promotes hepatic fatty acid oxidation - shows promise for alleviating the excessive fat exposure at the root of the diabetic syndrome, as well as the underlying insulin resistance syndrome responsible for increased macrovascular risk. However, when HT proves incapable of breaking the vicious cycle sustaining beta cell dysfunction, a supplementary strategy, beta cell redifferentiation therapy (BRT), may be required. BRT consists of a protocol in which near-normoglycemia is maintained for several weeks through use of intensive insulin therapy (e.g. artificial pancreas) or other effective measures, during which time beta cell GSIS can be expected to substantially recover owing to relief from glucolipotoxicity. Clinical experience demonstrates that this improved beta cell function, in certain cases, can persist for months or years after temporary BRT. A portion of the improved glycemic control achieved with very low calorie diets in NIDDM is reflective of improved GSIS, presumably consequent to a sustained reduction in diurnal glycemia. Long-lived analogs of glucagon-like peptide-1 (GLP-1) may find a key role in BRT; this incretin hormone not only potentiates GSIS, but also appears to increase the expression and activity of IDX-1 in beta cells, thus promoting beta cell redifferentiation. If HT is instituted prior to and following BRT to alleviate the FFA overexposure that initially precipitated the diabetic syndrome, it seems likely that the benefits of BRT will be conserved in the long term, thus enabling a reversal of NIDDM - in other words, maintenance of normoglycemia without medication. Since NIDDM is inherently preventable, its reversal should be the fundamental goal of diabetes therapy.
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Lee JS, Bruce CR, Tunstall RJ, Cameron-Smith D, Hugel H, Hawley JA. Interaction of exercise and diet on GLUT-4 protein and gene expression in Type I and Type II rat skeletal muscle. ACTA PHYSIOLOGICA SCANDINAVICA 2002; 175:37-44. [PMID: 11982503 DOI: 10.1046/j.1365-201x.2002.00963.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We determined the interaction of exercise and diet on glucose transporter (GLUT-4) protein and mRNA expression in type I (soleus) and type II [extensor digitorum longus (EDL)] skeletal muscle. Forty-eight Sprague Dawley rats were randomly assigned to one of two dietary conditions: high-fat (FAT, n=24) or high-carbohydrate (CHO, n=24). Animals in each dietary condition were allocated to one of two groups: control (NT, n=8) or a group that performed 8 weeks of treadmill running (4 sessions week-1 of 1000 m @ 28 m min-1, RUN, n=16). Eight trained rats were killed after their final exercise bout for determination of GLUT-4 protein and mRNA expression: the remainder were killed 48 h after their last session for measurement of muscle glycogen and triacylglycerol concentration. GLUT-4 protein expression in NT rats was similar in both muscles after 8 weeks of either diet. However, there was a main effect of training such that GLUT-4 protein was increased in the soleus of rats fed with either diet (P < 0.05) and in the EDL in animals fed with CHO (P < 0.05). There was a significant diet-training interaction on GLUT-4 mRNA, such that expression was increased in both the soleus (100% upward arrowP < 0.05) and EDL (142% upward arrowP < 0.01) in CHO-fed animals. Trained rats fed with FAT decreased mRNA expression in the EDL ( downward arrow 45%, P < 0.05) but not the soleus ( downward arrow 14%, NS). We conclude that exercise training in CHO-fed rats increased both GLUT-4 protein and mRNA expression in type I and type II skeletal muscle. Despite lower GLUT-4 mRNA in muscles from fat-fed animals, exercise-induced increases in GLUT-4 protein were largely preserved, suggesting that control of GLUT-4 protein and gene expression are modified independently by exercise and diet.
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Affiliation(s)
- J S Lee
- Exercise Metabolism Group, School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia
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26
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Mohammad A, Sharma V, McNeill JH. Vanadium increases GLUT4 in diabetic rat skeletal muscle. Mol Cell Biochem 2002; 233:139-43. [PMID: 12083368 DOI: 10.1023/a:1015558328757] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effect of vanadium in lowering blood glucose in diabetic animals is well established; however, the exact mechanism of action of vanadium still eludes us. There are several reports from in vitro studies indicating that vanadium increases enzyme activity in insulin signalling pathways; however, these findings have not been duplicated in vivo. Glucose transporters (GLUT) have a major role to play in any glucoregulatory effects. Insulin dependent GLUT4 is a major glucose transporter present in skeletal muscle, adipocytes and heart. In the present study we found that the plasma glucose in streptozotocin (STZ) diabetic animals was restored to normal following treatment with a single dose of BMOV, an organic vanadium compound, given by oral gavage (0.6 mmol/kg), similar to the response with chronic BMOV treatment. The response to BMOV by oral gavage was rapid and the animals were normoglycemic within 24 h of treatment and still demonstrated a significant effect even after 72 h. Using a specific antibody against GLUT4 we found an overall reduction in the GLUT4 in the total membrane fraction in skeletal muscle of diabetic animals. However, with a single dose of BMOV the GLUT4 level was restored to normal. This is the first report that establishes a direct effect of vanadium on the regulation of GLUT4 expression in diabetic animals in vivo, and may at least partially explain the glucoregulatory effects of vanadium.
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Affiliation(s)
- Askar Mohammad
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
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27
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Heled Y, Shapiro Y, Shani Y, Moran DS, Langzam L, Braiman L, Sampson SR, Meyerovitch J. Physical exercise prevents the development of type 2 diabetes mellitus in Psammomys obesus. Am J Physiol Endocrinol Metab 2002; 282:E370-5. [PMID: 11788369 DOI: 10.1152/ajpendo.00296.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that exercise training might prevent diabetes mellitus in Psammomys obesus. Animals were assigned to three groups: high-energy diet (CH), high-energy diet and exercise (EH), and low-energy diet (CL). The EH group ran on a treadmill 5 days/wk, twice a day. After 4 wk, 93% of the CH group were diabetic compared with only 20% of the EH group. There was no difference in weight gain among the groups. Both EH and CH groups were hyperinsulinemic. Epididymal fat (% of body weight) was higher in the CH group than in either the EH and or the CL group. Protein kinase C (PKC)-delta activity and serine phosphorylation were higher in the EH group. No differences were found in tyrosine phosphorylation of the insulin receptor, insulin receptor substrate-1, and phosphatidylinositol 3-kinase among the groups. We demonstrate for the first time that exercise training effectively prevents the progression of diabetes mellitus type 2 in Psammomys obesus. PKC-delta may be involved in the adaptive effects of exercise in skeletal muscles that lead to the prevention of type 2 diabetes mellitus.
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Affiliation(s)
- Yuval Heled
- Heller Institute of Medical Research, Tel Aviv University, Tel Aviv 52621, Israel
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Yu M, Blomstrand E, Chibalin AV, Krook A, Zierath JR. Marathon running increases ERK1/2 and p38 MAP kinase signalling to downstream targets in human skeletal muscle. J Physiol 2001; 536:273-82. [PMID: 11579175 PMCID: PMC2278852 DOI: 10.1111/j.1469-7793.2001.00273.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
1. We tested the hypothesis that long-distance running activates parallel mitogen-activated protein kinase (MAPK) cascades that involve extracellular signal regulated kinase 1 and 2 (ERK1/2) and p38 MAPK and their downstream substrates. 2. Eleven men completed a 42.2 km marathon (mean race time 4 h 1 min; range 2 h 56 min to 4 h 33 min). Vastus lateralis muscle biopsies were obtained before and after the race. Glycogen content was measured spectrophotometrically. ERK1/2 and p38 MAPK phosphorylation was determined by immunoblot analysis using phosphospecific antibodies. Activation of the downstream targets of ERK1/2 and p38 MAPK, MAPK-activated protein kinase-1 (MAPKAP-K1; also called p90 ribosomal S6 kinase, p90rsk), MAPK-activated protein kinase-2 (MAPKAP-K2), mitogen- and stress-activated kinase 1 (MSK1) and mitogen- and stress-activated kinase 2 (MSK2) was determined using immune complex assays. 3. Muscle glycogen content was reduced by 40 +/- 6 % after the marathon. ERK1/2 phosphorylation increased 7.8-fold and p38 MAPK phosphorylation increased 4.4-fold post-exercise. Prolonged running did not alter ERK1/2 and p38 MAPK protein expression. The activity of p90rsk, a downstream target of ERK1/2, increased 2.8-fold after the marathon. The activity of MAPKAPK-K2, a downstream target of p38 MAPK, increased 3.1-fold post-exercise. MSK1 and MSK2 are downstream of both ERK1/2 and p38 MAPK. MSK1 activity increased 2.4-fold post-exercise. MSK2 activity was low, relative to MSK1, with little activation post-exercise. 4. In conclusion, prolonged distance running activates MAPK signalling cascades in skeletal muscle, including increased activity of downstream targets: p90rsk, MAPKAP-K2 and MSK. Activation of these downstream targets provides a potential mechanism by which exercise induces gene transcription in skeletal muscle.
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Affiliation(s)
- M Yu
- Department of Clinical Physiology, Karolinska Hospital, Stockholm, Sweden
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Wadley GD, Tunstall RJ, Sanigorski A, Collier GR, Hargreaves M, Cameron-Smith D. Differential effects of exercise on insulin-signaling gene expression in human skeletal muscle. J Appl Physiol (1985) 2001; 90:436-40. [PMID: 11160039 DOI: 10.1152/jappl.2001.90.2.436] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle insulin sensitivity is enhanced after acute exercise and short-term endurance training. We investigated the impact of exercise on the gene expression of key insulin-signaling proteins in humans. Seven untrained subjects (4 women and 3 men) completed 9 days of cycling at 63 +/- 2% of peak O(2) uptake for 60 min/day. Muscle biopsies were taken before, immediately after, and 3 h after the exercise bouts (on days 1 and 9). The gene expression of insulin receptor substrate-2 and the p85 alpha subunit of phosphatidylinositol 3-kinase was significantly higher 3 h after a single exercise bout, although short-term training ameliorated this effect. Gene expression of insulin receptor and insulin receptor substrate-1 was not significantly altered at any time point. These results suggest that exercise may have a transitory impact on the expression of insulin receptor substrate-2 and phosphatidylinositol 3-kinase; however, the predominant actions of exercise on insulin sensitivity appear not to reside in the transcriptional activation of the genes encoding major insulin-signaling proteins.
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Affiliation(s)
- G D Wadley
- School of Health Sciences, Deakin University, Burwood, Victoria 3125, Australia
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Yu M, Blomstrand E, Chibalin AV, Wallberg-Henriksson H, Zierath JR, Krook A. Exercise-associated differences in an array of proteins involved in signal transduction and glucose transport. J Appl Physiol (1985) 2001; 90:29-34. [PMID: 11133890 DOI: 10.1152/jappl.2001.90.1.29] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vastus lateralis muscle biopsies were obtained from endurance-trained (running approximately 50 km/wk) and untrained (no regular physical exercise) men, and the expression of an array of insulin-signaling intermediates was determined. Expression of insulin receptor and insulin receptor substrate-1 and -2 was decreased 44% (P < 0.05), 57% (P < 0.001), and 77% (P < 0.001), respectively, in trained vs. untrained muscle. The downstream signaling target, Akt kinase, was not altered in trained subjects. Components of the mitogenic signaling cascade were also assessed. Extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase expression was 190% greater (P < 0.05), whereas p38 mitogen-activated protein kinase expression was 32% lower (P < 0.05), in trained vs. untrained muscle. GLUT-4 protein expression was twofold higher (P < 0.05), and the GLUT-4 vesicle-associated protein, the insulin-regulated aminopeptidase, was increased 4.7-fold (P < 0. 05) in trained muscle. In conclusion, the expression of proteins involved in signal transduction is altered in skeletal muscle from well-trained athletes. Downregulation of early components of the insulin-signaling cascade may occur in response to increased insulin sensitivity associated with endurance training.
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Affiliation(s)
- M Yu
- Department of Clinical Physiology, Karolinska Hospital, SE-171 76 Stockholm, Sweden
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Buhl ES, Jessen N, Schmitz O, Pedersen SB, Pedersen O, Holman GD, Lund S. Chronic treatment with 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside increases insulin-stimulated glucose uptake and GLUT4 translocation in rat skeletal muscles in a fiber type-specific manner. Diabetes 2001; 50:12-7. [PMID: 11147776 DOI: 10.2337/diabetes.50.1.12] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Recent studies have demonstrated that chronic administration of AICAR (5-aminoimidazole-4-carboxamide- 1-beta-D-ribofuranoside), an activator of the AMP-activated protein kinase, increases hexokinase activity and the contents of total GLUT4 and glycogen in rat skeletal muscles. To explore whether AICAR also affects insulin-stimulated glucose transport and GLUT4 cell surface content, Wistar rats were subcutaneously injected with AICAR for 5 days in succession (1 mg/g body wt). Maximally insulin-stimulated (60 nmol/l) glucose uptake was markedly increased in epitrochlearis (EPI) muscle (average 63%, P < 0.001, n = 18-19) and in extensor digitorum longus muscle (average 26%, P < 0.001, n = 26-30). In contrast, administration of AICAR did not maximally influence insulin-stimulated glucose transport in soleus muscle. Studies of EPI muscle with the 4,4'-O-[2-[2-[2-[2-[2-[6-(biotinylamino)hexanoyl]amino]ethoxy]ethoxy] ethoxy]-4-(1-azi-2,2,2,-trifluoroethyl)benzoyl]amino-1,3-propanediyl]bis-D-mannose photolabeling technique showed a concomitant increase (average 68%, P < 0.02) in cell surface GLUT4 content after insulin exposure in AICAR-injected rats when compared with controls. In conclusion, 5 days of AICAR administration induces a pronounced fiber type-specific increase in insulin-stimulated glucose uptake and GLUT4 cell surface content in rat skeletal muscle with the greatest effect observed on white fast-twitch glycolytic muscles (EPI). These results are comparable with the effects of chronic exercise training, and it brings the AMP-activated protein kinase into focus as a new interesting target for future pharmacological intervention in insulin-resistant conditions.
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Affiliation(s)
- E S Buhl
- Medical Department M, Aarhus Kommune-hospital, Denmark
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Abstract
Regular exercise has been shown to improve control of lipid abnormalities, diabetes mellitus, hypertension, and obesity, with the greatest benefits realized by sedentary individuals who begin to exercise. Responses to exercise interventions are often highly variable among individuals, however, and research has indicated that response to exercise may be mediated in large part by variation in genes. As we strive to unravel the complex etiology of diseases like obesity, diabetes, and cardiovascular disease through the use of molecular and genetic tools now available, understanding the interaction and influence of environmental factors, such as exercise, on gene expression and function has taken on increasing importance. This review briefly summarizes strategies presently being used to elucidate genes and genetic effects that may be mediated or influenced by exercise and serves to illustrate the importance of considering the effect of exercise when investigating genes related to health or other physiological outcomes.
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Affiliation(s)
- M S Bray
- Institute of Molecular Medicine, University of Texas-Houston, Houston, Texas 77030, USA.
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Abstract
A considerable amount of data have accumulated showing that contraction of muscle has an acute insulin-like effect, triggering the uptake of glucose. Chronic muscle contraction, as seen in endurance training has effects on insulin sensitivity, enhancing the effect of insulin on glucose uptake. Endurance training results in an increase in levels of GLUT4 in the muscle. This increase in GLUT4 is thought to be responsible in part for the enhancement of insulin sensitivity. Recent experiments have demonstrated that acute and chronic effects of muscle contraction on glucose uptake and the increase in GLUT4 may be due to activation of a protein kinase, AMP-activated protein kinase (AMPK). This kinase is activated by the increase in 5'-AMP and the decline in creatine phosphate that occur during muscle contraction. Phosphorylated AMPK then presumably phosphorylates undefined target proteins, which in turn increase glucose uptake and transcription of the GLUT4 gene. Experiments have demonstrated that this kinase, normally activated during exercise, can be activated artificially in muscle by injecting non-exercising rats with 5-aminoimidazole-4-carboxamide-riboside (AICAR), an adenosine analog. AICAR is taken up into muscle and phosphorylated to form an analog of 5'-AMP. Acute (stimulation of glucose uptake into muscle) and chronic (increase in GLUT4) effects of exercise can be reproduced by injection of this drug. These observations open the door to the possibility of treatment of patients with type 2 diabetes with AMPK activators.
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Affiliation(s)
- W W Winder
- Department of Zoology, Brigham Young University, Provo, Utah 84602, USA.
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Houmard JA, Shaw CD, Hickey MS, Tanner CJ. Effect of short-term exercise training on insulin-stimulated PI 3-kinase activity in human skeletal muscle. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:E1055-60. [PMID: 10600795 DOI: 10.1152/ajpendo.1999.277.6.e1055] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to determine if the improvement in insulin sensitivity with exercise training is associated with enhanced phosphatidylinositol 3-kinase (PI 3-kinase) activity. Nine sedentary men were studied before and after 7 days of exercise training (1 h/day, approximately 75% maximal oxygen consumption). Insulin sensitivity was determined with a euglycemic-hyperinsulinemic glucose clamp in the sedentary state and 15-17 h after the final exercise bout. PI 3-kinase activity was determined from samples (vastus lateralis) obtained in the fasted condition and after 60 min of submaximal insulin stimulation during the clamp. After exercise, glucose infusion rate increased (P < 0. 05) significantly (means +/- SE, 7.8 +/- 0.5 vs. 9.8 +/- 0.8 mg. kg(-1). min(-1)), indicating improved insulin sensitivity. Insulin-stimulated (insulin stimulated/fasting) phosphotyrosine immunoprecipitable PI 3-kinase activity also increased significantly (P < 0.05) with exercise (3.1 +/- 0.8-fold) compared with the sedentary condition (1.3 +/- 0.1-fold). There was no change in fasting PI 3-kinase activity. These data suggest that an enhancement of insulin signal transduction in skeletal muscle may contribute to the improvement in insulin action with exercise.
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Affiliation(s)
- J A Houmard
- Human Performance Laboratory and Department of Exercise and Sport Science, East Carolina University, Greenville, North Carolina 27858, USA.
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Holmes BF, Kurth-Kraczek EJ, Winder WW. Chronic activation of 5'-AMP-activated protein kinase increases GLUT-4, hexokinase, and glycogen in muscle. J Appl Physiol (1985) 1999; 87:1990-5. [PMID: 10562646 DOI: 10.1152/jappl.1999.87.5.1990] [Citation(s) in RCA: 359] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study was designed to determine whether chronic chemical activation of AMP-activated protein kinase (AMPK) would increase glucose transporter GLUT-4 and hexokinase in muscles similarly to periodic elevation of AMPK that accompanies endurance exercise training. The adenosine analog, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), has previously been shown to be taken up by cells and phosphorylated to form a compound (5-aminoimidazole-4-carboxamide ribonucleotide) that mimics the effect of AMP on AMPK. A single injection of AICAR resulted in a marked increase in AMPK in epitrochlearis and gastrocnemius/plantaris muscles 60 min later. When rats were injected with AICAR (1 mg/g body wt) for 5 days in succession and were killed 1 day after the last injection, GLUT-4 was increased by 100% in epitrochlearis muscle and by 60% in gastrocnemius muscle in response to AICAR. Hexokinase was also increased approximately 2. 5-fold in the gastrocnemius/plantaris. Gastrocnemius glycogen content was twofold higher in AICAR-treated rats than in controls. Chronic chemical activation of AMPK, therefore, results in increases in GLUT-4 protein, hexokinase activity, and glycogen, similarly to those induced by endurance training.
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Affiliation(s)
- B F Holmes
- Department of Zoology, Brigham Young University, Provo, Utah 84602, USA
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