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Aisyah R, Ohshima N, Watanabe D, Nakagawa Y, Sakuma T, Nitschke F, Nakamura M, Sato K, Nakahata K, Yokoyama C, Marchioni CR, Kumrungsee T, Shimizu T, Sotomaru Y, Takeo T, Nakagata N, Izumi T, Miura S, Minassian BA, Yamamoto T, Wada M, Yanaka N. GDE5/Gpcpd1 activity determines phosphatidylcholine composition in skeletal muscle and regulates contractile force in mice. Commun Biol 2024; 7:604. [PMID: 38769369 PMCID: PMC11106330 DOI: 10.1038/s42003-024-06298-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 05/07/2024] [Indexed: 05/22/2024] Open
Abstract
Glycerophosphocholine (GPC) is an important precursor for intracellular choline supply in phosphatidylcholine (PC) metabolism. GDE5/Gpcpd1 hydrolyzes GPC into choline and glycerol 3-phosphate; this study aimed to elucidate its physiological function in vivo. Heterozygous whole-body GDE5-deficient mice reveal a significant GPC accumulation across tissues, while homozygous whole-body knockout results in embryonic lethality. Skeletal muscle-specific GDE5 deletion (Gde5 skKO) exhibits reduced passive force and improved fatigue resistance in electrically stimulated gastrocnemius muscles in vivo. GDE5 deficiency also results in higher glycolytic metabolites and glycogen levels, and glycerophospholipids alteration, including reduced levels of phospholipids that bind polyunsaturated fatty acids (PUFAs), such as DHA. Interestingly, this PC fatty acid compositional change is similar to that observed in skeletal muscles of denervated and Duchenne muscular dystrophy mouse models. These are accompanied by decrease of GDE5 expression, suggesting a regulatory role of GDE5 activity for glycerophospholipid profiles. Furthermore, a DHA-rich diet enhances contractile force and lowers fatigue resistance, suggesting a functional relationship between PC fatty acid composition and muscle function. Finally, skinned fiber experiments show that GDE5 loss increases the probability of the ryanodine receptor opening and lowers the maximum Ca2+-activated force. Collectively, GDE5 activity plays roles in PC and glucose/glycogen metabolism in skeletal muscle.
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Affiliation(s)
- Rahmawati Aisyah
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | | | - Daiki Watanabe
- Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, Japan
- Graduate School of Sport and Health Sciences, Osaka University of Health and Sport Sciences, Osaka, Japan
| | - Yoshiko Nakagawa
- Center for Animal Resources and Development (CARD), Kumamoto University, Kumamoto, Japan
| | - Tetsushi Sakuma
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Felix Nitschke
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Minako Nakamura
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Koji Sato
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Kaori Nakahata
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Chihiro Yokoyama
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Charlotte R Marchioni
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | - Takahiko Shimizu
- Aging Stress Response Research Project Team, National Center for Geriatrics and Gerontology, Aichi, Japan
| | - Yusuke Sotomaru
- Natural Science Center for Basic Research and Development, Hiroshima University, Hiroshima, Japan
| | - Toru Takeo
- Center for Animal Resources and Development (CARD), Kumamoto University, Kumamoto, Japan
| | - Naomi Nakagata
- Center for Animal Resources and Development (CARD), Kumamoto University, Kumamoto, Japan
| | - Takashi Izumi
- Graduate School of Medicine, Gunma University, Gunma, Japan
- Faculty of Health Care, Teikyo Heisei University, Tokyo, Japan
| | - Shinji Miura
- Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan
| | - Berge A Minassian
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Takashi Yamamoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Masanobu Wada
- Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, Japan
| | - Noriyuki Yanaka
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan.
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Sammut MJ, McBey DP, Sayal AP, Melling CWJ. The Effects of Resistance Exercise Training on Skeletal Muscle Metabolism and Insulin Resistance Development in Female Rodents with Type 1 Diabetes. J Diabetes Res 2024; 2024:5549762. [PMID: 38435452 PMCID: PMC10904684 DOI: 10.1155/2024/5549762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 02/05/2024] [Accepted: 02/07/2024] [Indexed: 03/05/2024] Open
Abstract
The etiology of insulin resistance (IR) development in type 1 diabetes mellitus (T1DM) remains unclear; however, impaired skeletal muscle metabolism may play a role. While IR development has been established in male T1DM rodents, female rodents have yet to be examined in this context. Resistance exercise training (RT) has been shown to improve IR and is associated with a lower risk of hypoglycemia onset in T1DM compared to aerobic exercise. The purpose of this study was to investigate the effects of RT on IR development in female T1DM rodents. Forty Sprague Dawley eight-week-old female rats were divided into four groups: control sedentary (CS; n = 10), control trained (CT; n = 10), T1DM sedentary (DS; n = 10), and T1DM trained (DT; n = 10). Multiple low-dose streptozotocin injections were used to induce T1DM. Blood glucose levels were maintained in the 4-9 mmol/l range with intensive insulin therapy. CT and DT underwent weighted ladder climbing 5 days/week for six weeks. Intravenous glucose tolerance tests (IVGTT) were conducted on all animals following the six-week period. Results demonstrate that DS animals exhibited significantly increased weekly blood glucose measures compared to all groups including DT (p < 0.0001), despite similar insulin dosage levels. This was concomitant with a significant increase in insulin-adjusted area under the curve following IVGTT in DS (p < 0.05), indicative of a reduction in insulin sensitivity. Both DT and DS exhibited greater serum insulin concentrations compared to CT and CS (p < 0.05). DS animals also exhibited significantly greater glycogen content in white gastrocnemius muscle compared to CS and DT (p < 0.05), whereas DT and DS animals exhibited greater p-Akt: Akt ratio in the white vastus lateralis muscle and citrate synthase activity in the red vastus lateralis muscle compared to CS and CT (p < 0.05). These results indicate that female rodents with T1DM develop poor glycemic control and IR which can be attenuated with RT, possibly related to differences in intramyocellular glycogen content.
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Affiliation(s)
- Mitchell J. Sammut
- School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada
| | - David P. McBey
- School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada
| | - Amit P. Sayal
- School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada
| | - C. W. James Melling
- School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada
- Department of Physiology & Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
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3
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Grapentine S, Singh RK, Bakovic M. Skeletal Muscle Consequences of Phosphatidylethanolamine Synthesis Deficiency. FUNCTION 2023; 4:zqad020. [PMID: 37342414 PMCID: PMC10278983 DOI: 10.1093/function/zqad020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 04/24/2023] [Accepted: 04/25/2023] [Indexed: 06/22/2023] Open
Abstract
The maintenance of phospholipid homeostasis is increasingly being implicated in metabolic health. Phosphatidylethanolamine (PE) is the most abundant phospholipid on the inner leaflet of cellular membranes, and we have previously shown that mice with a heterozygous ablation of the PE synthesizing enzyme, Pcyt2 (Pcyt2+/-), develop obesity, insulin resistance, and NASH. Skeletal muscle is a major determinant of systemic energy metabolism, making it a key player in metabolic disease development. Both the total PE levels and the ratio of PE to other membrane lipids in skeletal muscle are implicated in insulin resistance; however, the underlying mechanisms and the role of Pcyt2 regulation in this association remain unclear. Here, we show how reduced phospholipid synthesis due to Pcyt2 deficiency causes Pcyt2+/- skeletal muscle dysfunction and metabolic abnormalities. Pcyt2+/- skeletal muscle exhibits damage and degeneration, with skeletal muscle cell vacuolization, disordered sarcomeres, mitochondria ultrastructure irregularities and paucity, inflammation, and fibrosis. There is intramuscular adipose tissue accumulation, and major disturbances in lipid metabolism with impaired FA mobilization and oxidation, elevated lipogenesis, and long-chain fatty acyl-CoA, diacylglycerol, and triacylglycerol accumulation. Pcyt2+/- skeletal muscle exhibits perturbed glucose metabolism with elevated glycogen content, impaired insulin signaling, and reduced glucose uptake. Together, this study lends insight into the critical role of PE homeostasis in skeletal muscle metabolism and health with broad implications on metabolic disease development.
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Affiliation(s)
- Sophie Grapentine
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph N1G 2W1, Canada
| | - Rathnesh K Singh
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph N1G 2W1, Canada
| | - Marica Bakovic
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph N1G 2W1, Canada
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4
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Hingst JR, Onslev JD, Holm S, Kjøbsted R, Frøsig C, Kido K, Steenberg DE, Larsen MR, Kristensen JM, Carl CS, Sjøberg K, Thong FSL, Derave W, Pehmøller C, Brandt N, McConell G, Jensen J, Kiens B, Richter EA, Wojtaszewski JFP. Insulin Sensitization Following a Single Exercise Bout Is Uncoupled to Glycogen in Human Skeletal Muscle: A Meta-analysis of 13 Single-Center Human Studies. Diabetes 2022; 71:2237-2250. [PMID: 36265014 DOI: 10.2337/db22-0015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 08/18/2022] [Indexed: 11/13/2022]
Abstract
Exercise profoundly influences glycemic control by enhancing muscle insulin sensitivity, thus promoting glucometabolic health. While prior glycogen breakdown so far has been deemed integral for muscle insulin sensitivity to be potentiated by exercise, the mechanisms underlying this phenomenon remain enigmatic. We have combined original data from 13 of our studies that investigated insulin action in skeletal muscle either under rested conditions or following a bout of one-legged knee extensor exercise in healthy young male individuals (n = 106). Insulin-stimulated glucose uptake was potentiated and occurred substantially faster in the prior contracted muscles. In this otherwise homogenous group of individuals, a remarkable biological diversity in the glucometabolic responses to insulin is apparent both in skeletal muscle and at the whole-body level. In contrast to the prevailing concept, our analyses reveal that insulin-stimulated muscle glucose uptake and the potentiation thereof by exercise are not associated with muscle glycogen synthase activity, muscle glycogen content, or degree of glycogen utilization during the preceding exercise bout. Our data further suggest that the phenomenon of improved insulin sensitivity in prior contracted muscle is not regulated in a homeostatic feedback manner from glycogen. Instead, we put forward the idea that this phenomenon is regulated by cellular allostatic mechanisms that elevate the muscle glycogen storage set point and enhance insulin sensitivity to promote the uptake of glucose toward faster glycogen resynthesis without development of glucose overload/toxicity or feedback inhibition.
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Affiliation(s)
- Janne R Hingst
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Johan D Onslev
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Stephanie Holm
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Kjøbsted
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Christian Frøsig
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Kohei Kido
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Dorte E Steenberg
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Magnus R Larsen
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Jonas M Kristensen
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Christian Strini Carl
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Kim Sjøberg
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Farah S L Thong
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Wim Derave
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Christian Pehmøller
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Nina Brandt
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Glenn McConell
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Jørgen Jensen
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
- Department of Physical Performance, Norwegian School of Sports Sciences, Oslo, Norway
| | - Bente Kiens
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Erik A Richter
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen F P Wojtaszewski
- The August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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Kido K, Egawa T, Watanabe S, Kawanaka K, Treebak JT, Hayashi T. Fasting potentiates insulin-mediated glucose uptake in rested and prior-contracted rat skeletal muscle. Am J Physiol Endocrinol Metab 2022; 322:E425-E435. [PMID: 35344394 DOI: 10.1152/ajpendo.00412.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A single bout of exercise can potentiate the effect of insulin on skeletal muscle glucose uptake via activation of the AMPK-TBC1 domain family member 4 (TBC1D4) pathway, which suggests a positive correlation between AMPK activation and insulin sensitization. In addition, prolonged fasting in rodents is known to upregulate and thereby synergistically enhance the effect of exercise on muscle AMPK activation. Therefore, fasting may potentiate the insulin-sensitizing effect of exercise. In the present study, we mimicked exercise by in situ muscle contraction and evaluated the effect of a 36-h fast on muscle contraction-induced insulin sensitization. Male Wistar rats weighing 150-170 g were allocated to either a 36-h fasting or feeding group. The extensor digitorum longus (EDL) muscles were electrically contracted via the common peroneal nerve for 10 min followed by a 3-h recovery period. EDL muscles were dissected and incubated in the presence or absence of submaximal insulin. Our results demonstrated that acute muscle contraction and 36 h of fasting additively upregulated AMPK pathway activation. Insulin-stimulated muscle glucose uptake and site-specific TBC1D4 phosphorylation were enhanced by prior muscle contraction in 36-h-fasted rats, but not in fed rats. Moreover, enhanced insulin-induced muscle glucose uptake and Akt phosphorylation due to 36 h of fasting were associated with a decrease in tribbles homolog 3 (TRB3), a negative regulator of Akt activation. In conclusion, fasting and prior muscle contraction synergistically enhance insulin-stimulated TBC1D4 phosphorylation and glucose uptake, which is associated with augmented AMPK pathway activation in rodents.NEW & NOTEWORTHY In this study, we revealed that 36 h of fasting additively upregulated acute muscle contraction-induced AMPK pathway activation in rats. Besides, fasting and muscle contraction synergistically enhanced insulin-stimulated site-specific TBC1D4 phosphorylation and glucose uptake, which was associated with augmented AMPK pathway activation. These results contribute to understanding the regulation of muscle insulin sensitivity.
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Affiliation(s)
- Kohei Kido
- Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan
- Faculty of Sports and Health Science, Fukuoka University, Fukuoka, Japan
- Institute for Physical Activity, Fukuoka University, Fukuoka, Japan
| | - Tatsuro Egawa
- Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan
| | - Shinya Watanabe
- Faculty of Sports and Health Science, Fukuoka University, Fukuoka, Japan
| | - Kentaro Kawanaka
- Faculty of Sports and Health Science, Fukuoka University, Fukuoka, Japan
- Institute for Physical Activity, Fukuoka University, Fukuoka, Japan
| | - Jonas T Treebak
- Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Tatsuya Hayashi
- Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan
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Norton L, Shannon C, Gastaldelli A, DeFronzo RA. Insulin: The master regulator of glucose metabolism. Metabolism 2022; 129:155142. [PMID: 35066003 DOI: 10.1016/j.metabol.2022.155142] [Citation(s) in RCA: 73] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 01/13/2022] [Accepted: 01/16/2022] [Indexed: 02/07/2023]
Abstract
Insulin is the master regulator of glucose, lipid, and protein metabolism. Following ingestion of an oral glucose load or mixed meal, the plasma glucose concentration rises, insulin secretion by the beta cells is stimulated and the hyperinsulinemia, working in concert with hyperglycemia, causes: (i) suppression of endogenous (primarily reflects hepatic) glucose production, (ii) stimulation of glucose uptake by muscle, liver, and adipocytes, (iii) inhibition of lipolysis leading to a decline in plasma FFA concentration which contributes to the suppression of hepatic glucose production and augmentation of muscle glucose uptake, and (iv) vasodilation in muscle, which contributes to enhanced muscle glucose disposal. Herein, the integrated physiologic impact of insulin to maintain normal glucose homeostasis is reviewed and the molecular basis of insulin's diverse actions in muscle, liver, adipocytes, and vasculature are discussed.
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Affiliation(s)
- Luke Norton
- Diabetes Division, UT Health, San Antonio, TX, United States of America
| | - Chris Shannon
- Diabetes Division, UT Health, San Antonio, TX, United States of America
| | - Amalia Gastaldelli
- Diabetes Division, UT Health, San Antonio, TX, United States of America; Cardiometabolic Risk Unit Institute of Clinical Physiology, CNR, Pisa, Italy
| | - Ralph A DeFronzo
- Diabetes Division, UT Health, San Antonio, TX, United States of America.
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Small SD, Margolis LM. Impact of Dietary Carbohydrate Restriction versus Energy Restriction on Exogenous Carbohydrate Oxidation during Aerobic Exercise. Adv Nutr 2021; 13:S2161-8313(22)00076-X. [PMID: 34788795 PMCID: PMC8970824 DOI: 10.1093/advances/nmab124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Individuals with high physical activity levels, such as athletes and military personnel, are likely to experience periods of low muscle glycogen content. Reductions in glycogen stores are associated with impaired physical performance. Lower glycogen stores in these populations are likely due to sustained aerobic exercise coupled with sub-optimal carbohydrate or energy intake. Consuming exogenous carbohydrate during aerobic exercise may be an effective intervention to sustain physical performance during periods of low glycogen. However, research is limited in the area of carbohydrate recommendations to fuel performance during periods of sub-optimal carbohydrate and energy intake. Additionally, the studies that have investigated the effects of low glycogen stores on exogenous carbohydrate oxidation have yielded conflicting results. Discrepancies between studies may be the result of glycogen stores being lowered by restricting carbohydrate or restricting energy intake. This narrative review discusses the influence of low glycogen status resulting from carbohydrate restriction versus energy restriction on exogenous carbohydrate oxidation and examines the potential mechanism resulting in divergent responses in exogenous carbohydrate oxidation. Results from this review indicate that rates of exogenous carbohydrate oxidation can be maintained when glycogen content is lower following carbohydrate restrictions, but may be reduced following energy restriction. Reductions in exogenous carbohydrate oxidation following energy restriction appear to result from lower insulin sensitivity and glucose uptake. Exogenous carbohydrate may thus be an effective intervention to sustain performance following short-term energy adequate carbohydrate restriction, but may not be an effective ergogenic aid when glycogen stores are low due to energy restriction.
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Affiliation(s)
- Stephanie D Small
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA,Oak Ridge Institute of Science and Education, Oak Ridge, TN, USA
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8
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Kolnes KJ, Petersen MH, Lien-Iversen T, Højlund K, Jensen J. Effect of Exercise Training on Fat Loss-Energetic Perspectives and the Role of Improved Adipose Tissue Function and Body Fat Distribution. Front Physiol 2021; 12:737709. [PMID: 34630157 PMCID: PMC8497689 DOI: 10.3389/fphys.2021.737709] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 09/02/2021] [Indexed: 12/13/2022] Open
Abstract
In obesity, excessive abdominal fat, especially the accumulation of visceral adipose tissue (VAT), increases the risk of metabolic disorders, such as type 2 diabetes mellitus (T2DM), cardiovascular disease, and non-alcoholic fatty liver disease. Excessive abdominal fat is associated with adipose tissue dysfunction, leading to systemic low-grade inflammation, fat overflow, ectopic lipid deposition, and reduced insulin sensitivity. Physical activity is recommended for primary prevention and treatment of obesity, T2DM, and related disorders. Achieving a stable reduction in body weight with exercise training alone has not shown promising effects on a population level. Because fat has a high energy content, a large amount of exercise training is required to achieve weight loss. However, even when there is no weight loss, exercise training is an effective method of improving body composition (increased muscle mass and reduced fat) as well as increasing insulin sensitivity and cardiorespiratory fitness. Compared with traditional low-to-moderate-intensity continuous endurance training, high-intensity interval training (HIIT) and sprint interval training (SIT) are more time-efficient as exercise regimens and produce comparable results in reducing total fat mass, as well as improving cardiorespiratory fitness and insulin sensitivity. During high-intensity exercise, carbohydrates are the main source of energy, whereas, with low-intensity exercise, fat becomes the predominant energy source. These observations imply that HIIT and SIT can reduce fat mass during bouts of exercise despite being associated with lower levels of fat oxidation. In this review, we explore the effects of different types of exercise training on energy expenditure and substrate oxidation during physical activity, and discuss the potential effects of exercise training on adipose tissue function and body fat distribution.
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Affiliation(s)
| | | | - Teodor Lien-Iversen
- Department of Internal Medicine, Randers Regional Hospital, Randers, Denmark
| | - Kurt Højlund
- Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
| | - Jørgen Jensen
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
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9
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Jelstad S, Ditta Valsdottir T, Johansen EI, Jensen JR. Eight sessions of endurance training decrease fasting glucose and improve glucose tolerance in middle-aged overweight males. Arch Physiol Biochem 2021; 127:12-19. [PMID: 30688111 DOI: 10.1080/13813455.2018.1563189] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Exercise improves metabolic regulation and reduces the risk of developing type 2 diabetes and other metabolic diseases. The recommendations for exercise are rather general and the health benefits of controlled training studies are important to make better recommendations. In the present study, we report that eight endurance training sessions over 3 weeks reduced fasting glucose, and improved glucose tolerance and plasma lipids in sedentary middle-aged males (44-64 years) with overweight or obesity (BMI: 27-38). The decrease in fasting glucose was substantial (from 5.3 ± 0.3 to 4.8 ± 0.2 mM; p < .001). The training sessions consisted of 60-min indoor-cycling at ∼83% of peak heart rate divided in four blocks of 15 min cycling, with 2-min rest between blocks. Maximal oxygen uptake did not increase (38.8 ± 1.8 vs. 39.0 ± 1.6 ml kg-1 min-1). In conclusion, 3-weekly sessions of moderate-/high-intensity endurance training can be recommended for untrained males with overweight or obesity to improve glucose homeostasis.
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Affiliation(s)
- Stian Jelstad
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Thorhildur Ditta Valsdottir
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
- Department of Medicine, Atlantis Medical University College, Oslo, Norway
| | - Egil I Johansen
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - J Rgen Jensen
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
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10
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Dahl MA, Areta JL, Jeppesen PB, Birk JB, Johansen EI, Ingemann-Hansen T, Hansen M, Skålhegg BS, Ivy JL, Wojtaszewski JFP, Overgaard K, Jensen J. Coingestion of protein and carbohydrate in the early recovery phase, compared with carbohydrate only, improves endurance performance despite similar glycogen degradation and AMPK phosphorylation. J Appl Physiol (1985) 2020; 129:297-310. [DOI: 10.1152/japplphysiol.00817.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endurance athletes competing consecutive days need optimal dietary intake during the recovery period. We report that coingestion of protein and carbohydrate soon after exhaustive exercise, compared with carbohydrate only, resulted in better performance the following day. The better performance after coingestion of protein and carbohydrate was not associated with a higher rate of glycogen synthesis or activation of anabolic signaling compared with carbohydrate only. Importantly, nitrogen balance was positive after coingestion of protein and carbohydrate, which was not the case after intake of carbohydrate only, suggesting that protein synthesis contributes to the better performance the following day.
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Affiliation(s)
- Marius A. Dahl
- Department of Physical Performance, Norwegian School of Sports Sciences, Oslo, Norway
| | - José Lisandro Areta
- Department of Physical Performance, Norwegian School of Sports Sciences, Oslo, Norway
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | | | - Jesper Bratz Birk
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Egil I. Johansen
- Department of Physical Performance, Norwegian School of Sports Sciences, Oslo, Norway
| | | | - Mette Hansen
- Department of Public Health, Aarhus University, Aarhus C, Denmark
| | - Bjørn Steen Skålhegg
- Department of Nutrition, Division for Molecular Nutrition, University of Oslo, Oslo, Norway
| | - John L. Ivy
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas
| | - Jørgen F. P. Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | | | - Jørgen Jensen
- Department of Physical Performance, Norwegian School of Sports Sciences, Oslo, Norway
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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11
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Mancilla R, Krook A, Schrauwen P, Hesselink MKC. Diurnal Regulation of Peripheral Glucose Metabolism: Potential Effects of Exercise Timing. Obesity (Silver Spring) 2020; 28 Suppl 1:S38-S45. [PMID: 32475086 PMCID: PMC7496481 DOI: 10.1002/oby.22811] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 03/23/2020] [Accepted: 03/23/2020] [Indexed: 12/18/2022]
Abstract
Diurnal oscillations in energy metabolism are linked to the activity of biological clocks and contribute to whole-body glucose homeostasis. Postprandially, skeletal muscle takes up approximately 80% of circulatory glucose and hence is a key organ in maintenance of glucose homeostasis. Dysregulation of molecular clock components in skeletal muscle disrupts whole-body glucose homeostasis. Next to light-dark cycles, nonphotic cues such as nutrient intake and physical activity are also potent cues to (re)set (dys)regulated clocks. Physical exercise is one of the most potent ways to improve myocellular insulin sensitivity. Given the role of the biological clock in glucose homeostasis and the power of exercise to improve insulin sensitivity, one can hypothesize that there might be an optimal time for exercise to maximally improve insulin sensitivity and glucose homeostasis. In this review, we aim to summarize the available information related to the interaction of diurnal rhythm, glucose homeostasis, and physical exercise as a nonphotic cue to correct dysregulation of human glucose metabolism.
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Affiliation(s)
- Rodrigo Mancilla
- Department of Nutrition and Movement SciencesNUTRIM School for Nutrition and Translational Research in MetabolismMaastricht University Medical Centre+MaastrichtThe Netherlands
| | - Anna Krook
- Department of Physiology and PharmacologySection for Integrative PhysiologyKarolinska InstitutetStockholmSweden
| | - Patrick Schrauwen
- Department of Nutrition and Movement SciencesNUTRIM School for Nutrition and Translational Research in MetabolismMaastricht University Medical Centre+MaastrichtThe Netherlands
| | - Matthijs K. C. Hesselink
- Department of Nutrition and Movement SciencesNUTRIM School for Nutrition and Translational Research in MetabolismMaastricht University Medical Centre+MaastrichtThe Netherlands
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Zhang Y, Yan LS, Ding Y, Cheng BCY, Luo G, Kong J, Liu TH, Zhang SF. Edgeworthia gardneri (Wall.) Meisn. Water Extract Ameliorates Palmitate Induced Insulin Resistance by Regulating IRS1/GSK3β/FoxO1 Signaling Pathway in Human HepG2 Hepatocytes. Front Pharmacol 2020; 10:1666. [PMID: 32082162 PMCID: PMC7002394 DOI: 10.3389/fphar.2019.01666] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 12/19/2019] [Indexed: 12/12/2022] Open
Abstract
The flower of Edgeworthia gardneri (Wall.) Meisn is commonly used in beverage products in Tibet and has potential health benefits for diabetes. However, the mechanisms underlying anti-insulin resistance (IR) action of the flower of E. gardneri are not fully understood. This study aims to investigate the effects of the water extract of the flower of E. gardneri (WEE) on IR in palmitate (PA)-exposed HepG2 hepatocytes. WEE was characterized by UPLC analysis. PA-treated HepG2 cells were selected as the IR cell model. The cell viability was determined using MTT assay. Moreover, the glucose consumption and production were measured by glucose oxidase method. The glucose uptake and glycogen content were determined by the 2-NBDG (2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl) amino]-D-glucose) glucose uptake assay and anthrone-sulfuric acid assay, respectively. The intracellular triglyceride content was detected by oxidative enzymic method. Protein levels were examined by Western blotting. Nuclear localization of FoxO1 was detected using immunofluorescence analyses and Western blotting. The expression of FoxO1 target genes was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The viability of PA-treated HepG2 cells was concentration-dependently increased by incubation with WEE for 24 h. WEE treatment remarkably increased the consumption and uptake of glucose in PA-exposed HepG2 cells. Moreover, treatment with WEE significantly decreased the PA-induced over-production of glucose in HepG2 cells. After exposure of HepG2 cells with PA and WEE, the glycogen content was significantly elevated. The phosphorylation and total levels of IRβ, IRS1, and Akt were upregulated by WEE treatment in PA-exposed HepG2 cells. The phosphorylation of GSK3β was elevated after WEE treatment in PA-treated cells. WEE treatment also concentration-dependently downregulated the phosphorylated CREB, ERK, c-Jun, p38 and JNK in PA-exposed HepG2 cells. Furthermore, the nuclear protein level and nuclear translocation of FoxO1 were also suppressed by WEE. Additionally, PA-induced changes of FoxO1 targeted genes were also attenuated by WEE treatment. The GLUT2 and GLUT4 translocation were also promoted by WEE treatment in PA-treated HepG2 cells. Taken together, WEE has potential anti-IR effect in PA-exposed HepG2 cells; the underlying mechanism of this action may be associated with the regulation of IRS1/GSK3β/FoxO1 signaling pathway. This study provides a pharmacological basis for the application of WEE in the treatment of metabolic diseases such as type 2 diabetes mellitus.
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Affiliation(s)
- Yi Zhang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Li Shan Yan
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Yu Ding
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Brian Chi Yan Cheng
- College of Professional and Continuing Education, Hong Kong Polytechnic University, Hong Kong, China
- Chinese Medicine Department of Quality Healthcare Medical Services , Hong Kong, China
| | - Gan Luo
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Jing Kong
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Tong Hua Liu
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
- Tibetan Medicine Department of Tibetan Traditional Medical College, Lhasa, China
| | - Shuo Feng Zhang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
- Tibetan Medicine Department of Tibetan Traditional Medical College, Lhasa, China
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Hingst JR, Bjerre RD, Wojtaszewski JFP, Jensen J. Rapid radiochemical filter paper assay for determination of hexokinase activity and affinity for glucose-6-phosphate. J Appl Physiol (1985) 2019; 127:661-667. [DOI: 10.1152/japplphysiol.00207.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glucose phosphorylation by hexokinase (HK) is a rate-limiting step in glucose metabolism. Regulation of HK includes feedback inhibition by its product glucose-6-phosphate (G6P) and mitochondria binding. HK affinity for G6P is difficult to measure because its natural product (G6P) inhibits enzyme activity. HK phosphorylates several hexoses, and we have taken advantage of the fact that 2-deoxyglucose (2-DG)-6-phosphate does not inhibit HK activity. By this, we have developed a new method for rapid radiochemical analysis of HK activity with 2-DG as a substrate, which allows control of the concentrations of G6P to investigate HK affinity for inhibition by G6P. We verified that 2-DG serves as a substrate for the HK reaction with linear time and concentration dependency as well as expected maximal velocity and KM. This is the first simple assay that evaluates feedback inhibition of HK by its product G6P and provides a unique technique for future research evaluating the regulation of glucose phosphorylation under various physiological conditions.NEW & NOTEWORTHY Traditionally, hexokinase activity has been analyzed spectrophotometrically in which the product formation of glucose-6-phosphate (G6P) is analyzed by an indirect reaction coupled to NADPH formation during conversion of G6P to 6-P gluconolactone. By nature, this assay prevents measurements of hexokinase (HK) affinity for inhibition by G6P. We have developed a rapid radiochemical filter paper assay to study HK affinity for G6P by use of radiolabeled 2-deoxyglucose as substrate to study physiological regulation of HK affinity for G6P-induced inhibition.
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Affiliation(s)
- Janne R. Hingst
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Rie D. Bjerre
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen F. P. Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen Jensen
- Department of Physical Performance, Norwegian School of Sports Sciences, Oslo, Norway
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Mattsson S, Jendle J, Adolfsson P. Carbohydrate Loading Followed by High Carbohydrate Intake During Prolonged Physical Exercise and Its Impact on Glucose Control in Individuals With Diabetes Type 1-An Exploratory Study. Front Endocrinol (Lausanne) 2019; 10:571. [PMID: 31496994 PMCID: PMC6712943 DOI: 10.3389/fendo.2019.00571] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 08/06/2019] [Indexed: 11/22/2022] Open
Abstract
Background: Prolonged physical exercise (PE) is a challenge in type 1 diabetes with an increased incidence of both hypoglycemia and hyperglycemia. Purpose: To evaluate the impact of two consecutive days of carbohydrate (CHO) loading, followed by high intermittent CHO-intake during prolonged PE, facilitated by a proactive use of Real-Time Continuous Glucose Monitoring (rtCGM), on glucose control in individuals with type 1 diabetes. Methods: Ten physically active individuals with type 1 diabetes were invited to participate in a 3-day long sports camp with the objective to evaluate CHO-loading and high intermittent CHO-intake during prolonged PE. 1.5 months later the same procedure was evaluated in relation to a 90 km cross-country skiing race (Vasaloppet). Participants were instructed to act proactively using rtCGM with predictive alerts to maintain sensor glucose values within target range, defined as 72-180 mg/dl (4-10 mmol/l). Results: Mean glucose values during CHO-loading were: day 1; 140.4 ± 45.0 mg/dl (7.8 ± 2.5 mmol/l) and day 2; 120.6 ± 41.4 mg/dl (6.7 ± 2.3 mmol/l). Mean sensor glucose at start of PE was 126.0 ± 25.2 mg/dl (7.0 ± 1.4 mmol/l) and throughout PE 127.8 ± 25.2 mg/dl (7.1 ± 1.4 mmol/l). Percentage of time spent in range (TIR) respective time spent in hypoglycemia was: CHO-loading 74.7/10.4% and during PE 94.3/0.6%. Conclusions: High intermittent CHO-intake during prolonged PE combined with proactive use of rtCGM is associated with good glycemic control during prolonged exercise in individuals with diabetes type 1. However, the time spent in hypoglycemia during the 2-days of CHO-loading was 10.4% and therefore a lower insulin dose might be suggested to reduce the time spent in hypoglycemia. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT03722225.
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Affiliation(s)
- Stig Mattsson
- Institute of Medical Sciences, Örebro University, Örebro, Sweden
- *Correspondence: Stig Mattsson
| | - Johan Jendle
- Institute of Medical Sciences, Örebro University, Örebro, Sweden
| | - Peter Adolfsson
- Department of Pediatrics, The Hospital of Halland, Kungsbacka, Sweden
- Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
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Shannon C, Merovci A, Xiong J, Tripathy D, Lorenzo F, McClain D, Abdul-Ghani M, Norton L, DeFronzo RA. Effect of Chronic Hyperglycemia on Glucose Metabolism in Subjects With Normal Glucose Tolerance. Diabetes 2018; 67:2507-2517. [PMID: 30213826 PMCID: PMC6245228 DOI: 10.2337/db18-0439] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 09/06/2018] [Indexed: 12/17/2022]
Abstract
Chronic hyperglycemia causes insulin resistance, but the inheritability of glucotoxicity and the underlying mechanisms are unclear. We examined the effect of 3 days of hyperglycemia on glucose disposal, enzyme activities, insulin signaling, and protein O-GlcNAcylation in skeletal muscle of individuals without (FH-) or with (FH+) family history of type 2 diabetes. Twenty-five subjects with normal glucose tolerance received a [3-3H]glucose euglycemic insulin clamp, indirect calorimetry, and vastus-lateralis biopsies before and after 3 days of saline (n = 5) or glucose (n = 10 FH- and 10 FH+) infusion to raise plasma glucose by ∼45 mg/dL. At baseline, FH+ had lower insulin-stimulated glucose oxidation and total glucose disposal (TGD) but similar nonoxidative glucose disposal and basal endogenous glucose production (bEGP) compared with FH- After 3 days of glucose infusion, bEGP and glucose oxidation were markedly increased, whereas nonoxidative glucose disposal and TGD were lower versus baseline, with no differences between FH- and FH+ subjects. Hyperglycemia doubled skeletal muscle glycogen content and impaired activation of glycogen synthase (GS), pyruvate dehydrogenase, and Akt, but protein O-GlcNAcylation was unchanged. Insulin resistance develops to a similar extent in FH- and FH+ subjects after chronic hyperglycemia, without increased protein O-GlcNAcylation. Decreased nonoxidative glucose disposal due to impaired GS activation appears to be the primary deficit in skeletal muscle glucotoxicity.
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Affiliation(s)
- Chris Shannon
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX
| | - Aurora Merovci
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX
| | - Juan Xiong
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX
| | - Devjit Tripathy
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX
| | - Felipe Lorenzo
- Center on Diabetes, Obesity, and Metabolism, Wake Forest University, Winston-Salem, NC
| | - Donald McClain
- Center on Diabetes, Obesity, and Metabolism, Wake Forest University, Winston-Salem, NC
| | - Muhammad Abdul-Ghani
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX
| | - Luke Norton
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX
| | - Ralph A DeFronzo
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX
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Hingst JR, Bruhn L, Hansen MB, Rosschou MF, Birk JB, Fentz J, Foretz M, Viollet B, Sakamoto K, Færgeman NJ, Havelund JF, Parker BL, James DE, Kiens B, Richter EA, Jensen J, Wojtaszewski JFP. Exercise-induced molecular mechanisms promoting glycogen supercompensation in human skeletal muscle. Mol Metab 2018; 16:24-34. [PMID: 30093357 PMCID: PMC6158101 DOI: 10.1016/j.molmet.2018.07.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 07/06/2018] [Accepted: 07/17/2018] [Indexed: 01/30/2023] Open
Abstract
Objective A single bout of exercise followed by intake of carbohydrates leads to glycogen supercompensation in prior exercised muscle. Our objective was to illuminate molecular mechanisms underlying this phenomenon in skeletal muscle of man. Methods We studied the temporal regulation of glycogen supercompensation in human skeletal muscle during a 5 day recovery period following a single bout of exercise. Nine healthy men depleted (day 1), normalized (day 2) and supercompensated (day 5) muscle glycogen in one leg while the contralateral leg served as a resting control. Euglycemic hyperinsulinemic clamps in combination with leg balance technique allowed for investigating insulin-stimulated leg glucose uptake under these 3 experimental conditions. Cellular signaling in muscle biopsies was investigated by global proteomic analyses and immunoblotting. We strengthened the validity of proposed molecular effectors by follow-up studies in muscle of transgenic mice. Results Sustained activation of glycogen synthase (GS) and AMPK in combination with elevated expression of proteins determining glucose uptake capacity were evident in the prior exercised muscle. We hypothesize that these alterations offset the otherwise tight feedback inhibition of glycogen synthesis and glucose uptake by glycogen. In line with key roles of AMPK and GS seen in the human experiments we observed abrogated ability for glycogen supercompensation in muscle with inducible AMPK deletion and in muscle carrying a G6P-insensitive form of GS in muscle. Conclusion Our study demonstrates that both AMPK and GS are key regulators of glycogen supercompensation following a single bout of glycogen-depleting exercise in skeletal muscle of both man and mouse. A single bout of exercise followed by carbohydrate intake leads to glycogen supersompensation in the prior exercised muscle. Skeletal muscle AMPK and glycogen synthase remain activated beyound normalized muscle glycogen content. Glycogen synthesis above resting levels is mediated independent of muscle insulin sensitivity.
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Affiliation(s)
- Janne R Hingst
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2100, Copenhagen, Denmark
| | - Lea Bruhn
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2100, Copenhagen, Denmark
| | - Mads B Hansen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2100, Copenhagen, Denmark
| | - Marie F Rosschou
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2100, Copenhagen, Denmark
| | - Jesper B Birk
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2100, Copenhagen, Denmark
| | - Joachim Fentz
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2100, Copenhagen, Denmark
| | - Marc Foretz
- INSERM, U1016, Institut Cochin, 75014, Paris, France; CNRS, UMR8104, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75014, Paris, France
| | - Benoit Viollet
- INSERM, U1016, Institut Cochin, 75014, Paris, France; CNRS, UMR8104, 75014, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75014, Paris, France
| | - Kei Sakamoto
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, United Kingdom
| | - Nils J Færgeman
- Department of Biochemistry and Molecular Biology and VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230, Odense, Denmark
| | - Jesper F Havelund
- Department of Biochemistry and Molecular Biology and VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230, Odense, Denmark
| | - Benjamin L Parker
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - David E James
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia; School of Medicine, University of Sydney, Sydney, NSW, 2006, Australia
| | - Bente Kiens
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2100, Copenhagen, Denmark
| | - Erik A Richter
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2100, Copenhagen, Denmark
| | - Jørgen Jensen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2100, Copenhagen, Denmark; Department of Physical Performance, Norwegian School of Sports Sciences, Oslo, Norway
| | - Jørgen F P Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2100, Copenhagen, Denmark.
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Restoration of Muscle Glycogen and Functional Capacity: Role of Post-Exercise Carbohydrate and Protein Co-Ingestion. Nutrients 2018; 10:nu10020253. [PMID: 29473893 PMCID: PMC5852829 DOI: 10.3390/nu10020253] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 02/11/2018] [Accepted: 02/15/2018] [Indexed: 12/31/2022] Open
Abstract
The importance of post-exercise recovery nutrition has been well described in recent years, leading to its incorporation as an integral part of training regimes in both athletes and active individuals. Muscle glycogen depletion during an initial prolonged exercise bout is a main factor in the onset of fatigue and so the replenishment of glycogen stores may be important for recovery of functional capacity. Nevertheless, nutritional considerations for optimal short-term (3–6 h) recovery remain incompletely elucidated, particularly surrounding the precise amount of specific types of nutrients required. Current nutritional guidelines to maximise muscle glycogen availability within limited recovery are provided under the assumption that similar fatigue mechanisms (i.e., muscle glycogen depletion) are involved during a repeated exercise bout. Indeed, recent data support the notion that muscle glycogen availability is a determinant of subsequent endurance capacity following limited recovery. Thus, carbohydrate ingestion can be utilised to influence the restoration of endurance capacity following exhaustive exercise. One strategy with the potential to accelerate muscle glycogen resynthesis and/or functional capacity beyond merely ingesting adequate carbohydrate is the co-ingestion of added protein. While numerous studies have been instigated, a consensus that is related to the influence of carbohydrate-protein ingestion in maximising muscle glycogen during short-term recovery and repeated exercise capacity has not been established. When considered collectively, carbohydrate intake during limited recovery appears to primarily determine muscle glycogen resynthesis and repeated exercise capacity. Thus, when the goal is to optimise repeated exercise capacity following short-term recovery, ingesting carbohydrate at an amount of ≥1.2 g kg body mass−1·h−1 can maximise muscle glycogen repletion. The addition of protein to carbohydrate during post-exercise recovery may be beneficial under circumstances when carbohydrate ingestion is sub-optimal (≤0.8 g kg body mass−1·h−1) for effective restoration of muscle glycogen and repeated exercise capacity.
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Jabbour G, Iancu HD. High-intensity exercise training does not influence body weight but improves lipid oxidation in obese adults: a 6-week RCT. BMJ Open Sport Exerc Med 2017; 3:e000283. [PMID: 29071116 PMCID: PMC5640093 DOI: 10.1136/bmjsem-2017-000283] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2017] [Indexed: 01/11/2023] Open
Abstract
OBJECTIVES This study examined the effects of 6 weeks of high-intensity training (HIT) on lipid oxidation (LO) rates during incremental exercises in obese adults. METHODS Twenty-four obese adults were randomised into a no-exercise control group (n=12; body mass index=33.3 (4.8) kg.m-2) and a HIT group (18 sessions of 6×6 s of supramaximal cycling and 2 min passive intervals; n=12; body mass index=33.2 (2.8)kg.m-2). The percentage of LO contribution was computed at rest and for all workloads (25, 50, 75, 100 and 125 W) in both groups before and after training via a graded maximal cycling test. RESULTS After training, the HIT group showed significantly higher LO at rest and at 25, 50 and 75 W compared with baseline (p<0.01) and the control group (p<0.01). Moreover, for the training group, the homoeostasis model assessment of insulin resistance (HOMA-IR) index decreased significantly from the baseline value (p<0.01) and the control group value (p<0.01). The increases in LO observed at rest and stages 25, 50 and 75 W were positively correlated with the declines in the HOMA-IR index (r=0.87, r=0.83, r=0.91 and r=0.88; p<0.01). CONCLUSION In obese adults, HIT increased lipid contributions to energy release at rest and in response to incremental exercise, while there were no changes in participants' aerobic capacity. This supports the hypothesis that metabolic changes rather than improved aerobic capacity are important to improve LO. TRIAL REGISTRATION NUMBER ISRCTN66508384. Stage: post-results.
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Affiliation(s)
- Georges Jabbour
- Sport Science Program, College of Arts and Sciences, Qatar University, Doha, Qatar
| | - Horia-Daniel Iancu
- School of Kinesiology and Leisure, Faculty of Health Sciences and Community Services, Université de Moncton, Moncton, New Brunswick, Canada
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Kjøbsted R, Wojtaszewski JFP, Treebak JT. Role of AMP-Activated Protein Kinase for Regulating Post-exercise Insulin Sensitivity. ACTA ACUST UNITED AC 2017; 107:81-126. [PMID: 27812978 DOI: 10.1007/978-3-319-43589-3_5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Skeletal muscle insulin resistance precedes development of type 2 diabetes (T2D). As skeletal muscle is a major sink for glucose disposal, understanding the molecular mechanisms involved in maintaining insulin sensitivity of this tissue could potentially benefit millions of people that are diagnosed with insulin resistance. Regular physical activity in both healthy and insulin-resistant individuals is recognized as the single most effective intervention to increase whole-body insulin sensitivity and thereby positively affect glucose homeostasis. A single bout of exercise has long been known to increase glucose disposal in skeletal muscle in response to physiological insulin concentrations. While this effect is identified to be restricted to the previously exercised muscle, the molecular basis for an apparent convergence between exercise- and insulin-induced signaling pathways is incompletely known. In recent years, we and others have identified the Rab GTPase-activating protein, TBC1 domain family member 4 (TBC1D4) as a target of key protein kinases in the insulin- and exercise-activated signaling pathways. Our working hypothesis is that the AMP-activated protein kinase (AMPK) is important for the ability of exercise to insulin sensitize skeletal muscle through TBC1D4. Here, we aim to provide an overview of the current available evidence linking AMPK to post-exercise insulin sensitivity.
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Affiliation(s)
- Rasmus Kjøbsted
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 2200, Copenhagen, Denmark
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Jørgen F P Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Jonas T Treebak
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 2200, Copenhagen, Denmark.
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Camacho LE, Chen X, Hay WW, Limesand SW. Enhanced insulin secretion and insulin sensitivity in young lambs with placental insufficiency-induced intrauterine growth restriction. Am J Physiol Regul Integr Comp Physiol 2017; 313:R101-R109. [PMID: 28490449 PMCID: PMC5582953 DOI: 10.1152/ajpregu.00068.2017] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/03/2017] [Accepted: 05/08/2017] [Indexed: 11/22/2022]
Abstract
Intrauterine growth restriction (IUGR) is associated with persistent metabolic complications, but information is limited for IUGR infants. We determined glucose-stimulated insulin secretion (GSIS) and insulin sensitivity in young lambs with placental insufficiency-induced IUGR. Lambs with hyperthermia-induced IUGR (n = 7) were compared with control lambs (n = 8). GSIS was measured at 8 ± 1 days of age, and at 15 ± 1 days, body weight-specific glucose utilization rates were measured with radiolabeled d-glucose during a hyperinsulinemic-euglycemic clamp (HEC). IUGR lambs weighed 23% less (P < 0.05) than controls at birth. Fasting plasma glucose and insulin concentrations were not different between IUGR and controls for either study. First-phase insulin secretion was enhanced 2.3-fold in IUGR lambs compared with controls. However, second-phase insulin concentrations, glucose-potentiated arginine-stimulated insulin secretion, and β-cell mass were not different, indicating that IUGR β-cells have an intrinsic enhancement in acute GSIS. Compared with controls, IUGR lambs had higher body weight-specific glucose utilization rates and greater insulin sensitivity at fasting (1.6-fold) and hyperinsulinemic periods (2.4-fold). Improved insulin sensitivity for glucose utilization was not due to differences in skeletal muscle insulin receptor and glucose transporters 1 and 4 concentrations. Plasma lactate concentrations during HEC were elevated in IUGR lambs compared with controls, but no differences were found for glycogen content or citrate synthase activity in liver and muscle. Greater insulin sensitivity for glucose utilization and enhanced acute GSIS in young lambs are predicted from fetal studies but may promote conditions that exaggerate glucose disposal and lead to episodes of hypoglycemia in IUGR infants.
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Affiliation(s)
- Leticia E Camacho
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Xiaochuan Chen
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona.,Chongqing Key Laboratory of Forage & Herbivore, College of Animal Science and Technology, Southwest University, Chongqing, China; and
| | - William W Hay
- Perinatal Research Center, University of Colorado School of Medicine, Aurora, Colorado
| | - Sean W Limesand
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona;
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Jensen J, O'Rahilly S. AMPK is required for exercise to enhance insulin sensitivity in skeletal muscles. Mol Metab 2017; 6:315-316. [PMID: 28377870 PMCID: PMC5369262 DOI: 10.1016/j.molmet.2017.01.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 01/18/2017] [Indexed: 10/26/2022] Open
Affiliation(s)
- Jørgen Jensen
- Department of Physical Performance, Norwegian School of Sport Sciences, Norway.
| | - Stephen O'Rahilly
- Welcome Trust-MRC Institute of Metabolic Science, University of Cambridge, United Kingdom
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22
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Jabbour G, Mauriege P, Joanisse D, Iancu HD. Effect of supramaximal exercise training on metabolic outcomes in obese adults. J Sports Sci 2016; 35:1975-1981. [DOI: 10.1080/02640414.2016.1243798] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Georges Jabbour
- School of Kinesiology and Leisure, Faculty of Health Sciences and Community Services, Université de Moncton, Moncton, Canada
| | | | - Denis Joanisse
- Department of Kinesiology, University of Laval, Laval, Canada
| | - Horia-Daniel Iancu
- School of Kinesiology and Leisure, Faculty of Health Sciences and Community Services, Université de Moncton, Moncton, Canada
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Scheffler TL, Park S, Roach PJ, Gerrard DE. Gain of function AMP-activated protein kinase γ3 mutation (AMPKγ3R200Q) in pig muscle increases glycogen storage regardless of AMPK activation. Physiol Rep 2016; 4:4/11/e12802. [PMID: 27302990 PMCID: PMC4908487 DOI: 10.14814/phy2.12802] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 04/28/2016] [Indexed: 01/18/2023] Open
Abstract
Chronic activation of AMP‐activated protein kinase (AMPK) increases glycogen content in skeletal muscle. Previously, we demonstrated that a mutation in the ryanodine receptor (RyR1R615C) blunts AMPK phosphorylation in longissimus muscle of pigs with a gain of function mutation in the AMPKγ3 subunit (AMPKγ3R200Q); this may decrease the glycogen storage capacity of AMPKγ3R200Q + RyR1R615C muscle. Therefore, our aim in this study was to utilize our pig model to understand how AMPKγ3R200Q and AMPK activation contribute to glycogen storage and metabolism in muscle. We selected and bred pigs in order to generate offspring with naturally occurring AMPKγ3R200Q, RyR1R615C, and AMPKγ3R200Q + RyR1R615C mutations, and also retained wild‐type littermates (control). We assessed glycogen content and parameters of glycogen metabolism in longissimus muscle. Regardless of RyR1R615C, AMPKγ3R200Q increased the glycogen content by approximately 70%. Activity of glycogen synthase (GS) without the allosteric activator glucose 6‐phosphate (G6P) was decreased in AMPKγ3R200Q relative to all other genotypes, whereas both AMPKγ3R200Q and AMPKγ3R200Q + RyR1R615C muscle exhibited increased GS activity with G6P. Increased activity of GS with G6P was not associated with increased abundance of GS or hexokinase 2. However, AMPKγ3R200Q enhanced UDP‐glucose pyrophosphorylase 2 (UGP2) expression approximately threefold. Although UGP2 is not generally considered a rate‐limiting enzyme for glycogen synthesis, our model suggests that UGP2 plays an important role in increasing flux to glycogen synthase. Moreover, we have shown that the capacity for glycogen storage is more closely related to the AMPKγ3R200Q mutation than activity.
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Affiliation(s)
- Tracy L Scheffler
- Department of Animal and Poultry Sciences, Litton-Reaves Hall, Virginia Tech, Blacksburg, Virginia
| | - Sungkwon Park
- Department of Animal and Poultry Sciences, Litton-Reaves Hall, Virginia Tech, Blacksburg, Virginia
| | - Peter J Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - David E Gerrard
- Department of Animal and Poultry Sciences, Litton-Reaves Hall, Virginia Tech, Blacksburg, Virginia
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Maile CA, Hingst JR, Mahalingan KK, O'Reilly AO, Cleasby ME, Mickelson JR, McCue ME, Anderson SM, Hurley TD, Wojtaszewski JFP, Piercy RJ. A highly prevalent equine glycogen storage disease is explained by constitutive activation of a mutant glycogen synthase. Biochim Biophys Acta Gen Subj 2016; 1861:3388-3398. [PMID: 27592162 DOI: 10.1016/j.bbagen.2016.08.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/15/2016] [Accepted: 08/30/2016] [Indexed: 01/16/2023]
Abstract
BACKGROUND Equine type 1 polysaccharide storage myopathy (PSSM1) is associated with a missense mutation (R309H) in the glycogen synthase (GYS1) gene, enhanced glycogen synthase (GS) activity and excessive glycogen and amylopectate inclusions in muscle. METHODS Equine muscle biochemical and recombinant enzyme kinetic assays in vitro and homology modelling in silico, were used to investigate the hypothesis that higher GS activity in affected horse muscle is caused by higher GS expression, dysregulation, or constitutive activation via a conformational change. RESULTS PSSM1-affected horse muscle had significantly higher glycogen content than control horse muscle despite no difference in GS expression. GS activity was significantly higher in muscle from homozygous mutants than from heterozygote and control horses, in the absence and presence of the allosteric regulator, glucose 6 phosphate (G6P). Muscle from homozygous mutant horses also had significantly increased GS phosphorylation at sites 2+2a and significantly higher AMPKα1 (an upstream kinase) expression than controls, likely reflecting a physiological attempt to reduce GS enzyme activity. Recombinant mutant GS was highly active with a considerably lower Km for UDP-glucose, in the presence and absence of G6P, when compared to wild type GS, and despite its phosphorylation. CONCLUSIONS Elevated activity of the mutant enzyme is associated with ineffective regulation via phosphorylation rendering it constitutively active. Modelling suggested that the mutation disrupts a salt bridge that normally stabilises the basal state, shifting the equilibrium to the enzyme's active state. GENERAL SIGNIFICANCE This study explains the gain of function pathogenesis in this highly prevalent polyglucosan myopathy.
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Affiliation(s)
- C A Maile
- Comparative Neuromuscular Diseases Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, London, UK
| | - J R Hingst
- Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark
| | - K K Mahalingan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, USA
| | - A O O'Reilly
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK
| | - M E Cleasby
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - J R Mickelson
- Veterinary Biomedical Sciences Department, University of Minnesota, St. Paul, MN, USA
| | - M E McCue
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, USA
| | - S M Anderson
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, USA
| | - T D Hurley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, USA
| | - J F P Wojtaszewski
- Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark
| | - R J Piercy
- Comparative Neuromuscular Diseases Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, London, UK.
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Pedersen AJT, Hingst JR, Friedrichsen M, Kristensen JM, Højlund K, Wojtaszewski JFP. Dysregulation of muscle glycogen synthase in recovery from exercise in type 2 diabetes. Diabetologia 2015; 58:1569-78. [PMID: 25870023 DOI: 10.1007/s00125-015-3582-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 03/13/2015] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS Insulin and exercise stimulate skeletal muscle glycogen synthase (GS) activity by dephosphorylation and changes in kinetic properties. The aim of this study was to investigate the effects of insulin, exercise and post-exercise insulin stimulation on GS phosphorylation, activity and substrate affinity in obesity and type 2 diabetes. METHODS Obese men with type 2 diabetes (n = 13) and weight-matched controls (n = 14) underwent euglycaemic-hyperinsulinaemic clamps in the rested state and 3 h after 60 min of cycling (70% maximal pulmonary oxygen uptake [VO2max]). Biopsies from vastus lateralis muscle were obtained before and after clamps, and before and immediately after exercise. RESULTS Insulin-stimulated glucose uptake was lower in diabetic patients vs obese controls with or without prior exercise. Post exercise, glucose partitioning shifted away from oxidation and towards storage in both groups. Insulin and, more potently, exercise increased GS activity (fractional velocity [FV]) and substrate affinity in both groups. Both stimuli caused dephosphorylation of GS at sites 3a + 3b, with exercise additionally decreasing phosphorylation at sites 2 + 2a. In both groups, changes in GS activity, substrate affinity and dephosphorylation at sites 3a + 3b by exercise were sustained 3 h post exercise and further enhanced by insulin. Post exercise, reduced GS activity and substrate affinity as well as increased phosphorylation at sites 2 + 2a were found in diabetic patients vs obese controls. CONCLUSIONS/INTERPRETATION Exercise-induced activation of muscle GS in obesity and type 2 diabetes involves dephosphorylation of GS at sites 3a + 3b and 2 + 2a and enhanced substrate affinity, which is likely to facilitate glucose partitioning towards storage. Lower GS activity and increased phosphorylation at sites 2 + 2a in type 2 diabetes in the recovery period imply an impaired response to exercise.
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26
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Sen I, Bozkurt O, Aras E, Heise S, Brockmann GA, Severcan F. Lipid profiles of adipose and muscle tissues in mouse models of juvenile onset of obesity without high fat diet induction: a Fourier transform infrared (FT-IR) spectroscopic study. APPLIED SPECTROSCOPY 2015; 69:679-688. [PMID: 26054332 DOI: 10.1366/14-07443] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The current study aims to determine lipid profiles in terms of the content and structure of skeletal muscle and adipose tissues to better understand the characteristics of juvenile-onset spontaneous obesity without high fat diet induction. For the purposes of this study, muscle (longissimus, quadriceps) and adipose (inguinal, gonadal) tissues of 10-week-old male DBA/2J and Berlin fat mouse inbred (BFMI) lines (BFMI856, BFMI860, BFMI861) fed with a standard breeding diet were used. Biomolecular structure and composition was determined using attenuated total reflection Fourier transform (ATR FT-IR) spectroscopy, and muscle triglyceride content was further quantified using high-performance liquid chromatography (HPLC) coupled with an evaporative light scattering detector (ELSD). The results revealed a loss of unsaturation in BFMI860 and BFMI861 lines in both muscles and inguinal adipose tissue, together with a decrease in the hydrocarbon chain length of lipids, especially in the BFMI860 line in muscles, suggesting an increased lipid peroxidation. There was an increase in saturated lipid and triglyceride content in all tissues of BFMI lines, more profoundly in longissimus muscle, where the increased triglyceride content was quantitatively confirmed by HPLC-ELSD. Moreover, an increase in the metabolic turnover of carbohydrates in muscles of the BFMI860 line was observed. The results demonstrated that subcutaneous (inguinal) fat also displayed considerable obesity-induced alterations. Taken together, the results revealed differences in lipid structure and content of BFMI lines, which may originate from different insulin sensitivity levels of the lines, making them promising animal models for spontaneous obesity. The results will contribute to the understanding of the generation of insulin resistance in obesity without high fat diet induction.
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Affiliation(s)
- Ilke Sen
- Middle East Technical University, Department of Biological Sciences, 06800 Ankara, Turkey
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27
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Brull A, de Luna N, Blanco-Grau A, Lucia A, Martin MA, Arenas J, Martí R, Andreu AL, Pinós T. Phenotype consequences of myophosphorylase dysfunction: insights from the McArdle mouse model. J Physiol 2015; 593:2693-706. [PMID: 25873271 DOI: 10.1113/jp270085] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 04/10/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS This is the first study to analyse the effect of muscle glycogen phosphorylase depletion in metabolically different muscle types. In McArdle mice, muscle glycogen phosphorylase is absent in both oxidative and glycolytic muscles. In McArdle mice, the glycogen debranching enzyme (catabolic) is increased in oxidative muscles, whereas the glycogen branching enzyme (anabolic) is increased in glycolytic muscles. In McArdle mice, total glycogen synthase is decreased in both oxidative and glycolytic muscles, whereas the phosphorylated inactive form of the enzyme is increased in both oxidative and glycolytic enzymes. In McArdle mice, glycogen content is higher in glycolytic muscles than in oxidative muscles. Additionally, in all muscles analysed, the glycogen content is higher in males than in females. The maximal endurance capacity of the McArdle mice is significantly lower compared to heterozygous and wild-type mice. ABSTRACT McArdle disease, caused by inherited deficiency of the enzyme muscle glycogen phosphorylase (GP-MM), is arguably the paradigm of exercise intolerance. The recent knock-in (p.R50X/p.R50X) mouse disease model allows an investigation of the phenotypic consequences of muscle glycogen unavailability and the physiopathology of exercise intolerance. We analysed, in 2-month-old mice [wild-type (wt/wt), heterozygous (p.R50X/wt) and p.R50X/p.R50X)], maximal endurance exercise capacity and the molecular consequences of an absence of GP-MM in the main glycogen metabolism regulatory enzymes: glycogen synthase, glycogen branching enzyme and glycogen debranching enzyme, as well as glycogen content in slow-twitch (soleus), intermediate (gastrocnemius) and glycolytic/fast-twitch (extensor digitorum longus; EDL) muscles. Compared with wt/wt, exercise capacity (measured in a treadmill test) was impaired in p.R50X/p.R50X (∼48%) and p.R50X/wt mice (∼18%). p.R50X/p.R50X mice showed an absence of GP-MM in the three muscles. GP-MM was reduced in p.R50X/wt mice, especially in the soleus, suggesting that the function of 'slow-twitch' muscles is less dependent on glycogen catabolism. p.R50X/p.R50X mice showed increased glycogen debranching enzyme in the soleus, increased glycogen branching enzyme in the gastrocnemius and EDL, as well as reduced levels of mucle glycogen synthase protein in the three muscles (mean ∼70%), reflecting a protective mechanism for preventing deleterious glycogen accumulation. Additionally, glycogen content was highest in the EDL of p.R50X/p.R50X mice. Amongst other findings, the present study shows that the expression of the main muscle glycogen regulatory enzymes differs depending on the muscle phenotype (slow- vs. fast-twitch) and that even partial GP-MM deficiency affects maximal endurance capacity. Our knock-in model might help to provide insights into the importance of glycogen on muscle function.
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Affiliation(s)
- Astrid Brull
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
| | - Noemí de Luna
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
| | - Albert Blanco-Grau
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Alejandro Lucia
- Universidad Europea, Madrid, Spain.,Instituto de Investigación 'i+12', Madrid, Spain
| | | | | | - Ramon Martí
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
| | - Antoni L Andreu
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
| | - Tomàs Pinós
- Neuromuscular and Mitochondrial Disorders Laboratory, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.,Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
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Improvement of endurance of DMD animal model using natural polyphenols. BIOMED RESEARCH INTERNATIONAL 2015; 2015:680615. [PMID: 25861640 PMCID: PMC4377377 DOI: 10.1155/2015/680615] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 08/13/2014] [Accepted: 08/27/2014] [Indexed: 12/11/2022]
Abstract
Duchenne muscular dystrophy (DMD), the most common form of muscular dystrophy, is characterized by muscular wasting caused by dystrophin deficiency that ultimately ends in force reduction and premature death. In addition to primary genetic defect, several mechanisms contribute to DMD pathogenesis. Recently, antioxidant supplementation was shown to be effective in the treatment of multiple diseases including muscular dystrophy. Different mechanisms were hypothesized such as reduced hydroxyl radicals, nuclear factor-κB deactivation, and NO protection from inactivation. Following these promising evidences, we investigated the effect of the administration of a mix of dietary natural polyphenols (ProAbe) on dystrophic mdx mice in terms of muscular architecture and functionality. We observed a reduction of muscle fibrosis deposition and myofiber necrosis together with an amelioration of vascularization. More importantly, the recovery of the morphological features of dystrophic muscle leads to an improvement of the endurance of treated dystrophic mice. Our data confirmed that ProAbe-based diet may represent a strategy to coadjuvate the treatment of DMD.
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29
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Kolnes AJ, Birk JB, Eilertsen E, Stuenæs JT, Wojtaszewski JFP, Jensen J. Epinephrine-stimulated glycogen breakdown activates glycogen synthase and increases insulin-stimulated glucose uptake in epitrochlearis muscles. Am J Physiol Endocrinol Metab 2015; 308:E231-40. [PMID: 25465888 DOI: 10.1152/ajpendo.00282.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epinephrine increases glycogen synthase (GS) phosphorylation and decreases GS activity but also stimulates glycogen breakdown, and low glycogen content normally activates GS. To test the hypothesis that glycogen content directly regulates GS phosphorylation, glycogen breakdown was stimulated in condition with decreased GS activation. Saline or epinephrine (0.02 mg/100 g rat) was injected subcutaneously in Wistar rats (∼130 g) with low (24-h-fasted), normal (normal diet), and high glycogen content (fasted-refed), and epitrochlearis muscles were removed after 3 h and incubated ex vivo, eliminating epinephrine action. Epinephrine injection reduced glycogen content in epitrochlearis muscles with high (120.7 ± 17.8 vs. 204.6 ± 14.5 mmol/kg, P < 0.01) and normal glycogen (89.5 ± 7.6 vs. 152 ± 8.1 mmol/kg, P < 0.01), but not significantly in muscles with low glycogen (90.0 ± 5.0 vs. 102.8 ± 7.8 mmol/kg, P = 0.17). In saline-injected rats, GS phosphorylation at sites 2+2a, 3a+3b, and 1b was higher and GS activity lower in muscles with high compared with low glycogen. GS sites 2+2a and 3a+3b phosphorylation decreased and GS activity increased in muscles where epinephrine decreased glycogen content; these parameters were unchanged in epitrochlearis from fasted rats where epinephrine injection did not decrease glycogen content. Incubation with insulin decreased GS site 3a+3b phosphorylation independently of glycogen content. Insulin-stimulated glucose uptake was increased in muscles where epinephrine injection decreased glycogen content. In conclusion, epinephrine stimulates glycogenolysis in epitrochlearis muscles with normal and high, but not low, glycogen content. Epinephrine-stimulated glycogenolysis decreased GS phosphorylation and increased GS activity. These data for the first time document direct regulation of GS phosphorylation by glycogen content.
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Affiliation(s)
- Anders J Kolnes
- Charles University Third Faculty of Medicine, Prague, Czech Republic
| | - Jesper B Birk
- Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, Copenhagen University, Copenhagen, Denmark
| | - Einar Eilertsen
- National Institute of Occupational Health, Oslo, Norway; and
| | - Jorid T Stuenæs
- National Institute of Occupational Health, Oslo, Norway; and
| | - Jørgen F P Wojtaszewski
- Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, Copenhagen University, Copenhagen, Denmark
| | - Jørgen Jensen
- Molecular Physiology Group, The August Krogh Centre, Department of Nutrition, Exercise and Sports, Copenhagen University, Copenhagen, Denmark; Department of Physical Performance, Norwegian School of Sports Sciences, Oslo, Norway
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30
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Chen SS, Otero YF, Mulligan KX, Lundblad TM, Williams PE, McGuinness OP. Liver, but not muscle, has an entrainable metabolic memory. PLoS One 2014; 9:e86164. [PMID: 24465939 PMCID: PMC3900485 DOI: 10.1371/journal.pone.0086164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 12/06/2013] [Indexed: 02/05/2023] Open
Abstract
Hyperglycemia in the hospitalized setting is common, especially in patients that receive nutritional support either continuously or intermittently. As the liver and muscle are the major sites of glucose disposal, we hypothesized their metabolic adaptations are sensitive to the pattern of nutrient delivery. Chronically catheterized, well-controlled depancreatized dogs were placed on one of three isocaloric diets: regular chow diet once daily (Chow) or a simple nutrient diet (ND) that was given either once daily (ND-4) or infused continuously (ND-C). Intraportal insulin was infused to maintain euglycemia. After 5 days net hepatic (NHGU) and muscle (MGU) glucose uptake and oxidation were assessed at euglycemia (120 mg/dl) and hyperglycemia (200 mg/dl) in the presence of basal insulin. While hyperglycemia increased both NHGU and MGU in Chow, NHGU was amplified in both groups receiving ND. The increase was associated with enhanced activation of glycogen synthase, glucose oxidation and suppression of pyruvate dehydrogenase kinase-4 (PDK-4). Accelerated glucose-dependent muscle glucose uptake was only evident with ND-C. This was associated with a decrease in PDK-4 expression and an increase in AMP-activated protein kinase (AMPK) phosphorylation. Interestingly, ND-C markedly increased hepatic FGF-21 expression. Thus, augmentation of carbohydrate disposal in the liver, as opposed to the muscle, is not dependent on the pattern of nutrient delivery.
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Affiliation(s)
- Sheng-Song Chen
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Yolanda F. Otero
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Kimberly X. Mulligan
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Tammy M. Lundblad
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Phillip E. Williams
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Owen P. McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail:
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Myers SA, Nield A, Chew GS, Myers MA. The zinc transporter, Slc39a7 (Zip7) is implicated in glycaemic control in skeletal muscle cells. PLoS One 2013; 8:e79316. [PMID: 24265765 PMCID: PMC3827150 DOI: 10.1371/journal.pone.0079316] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 09/22/2013] [Indexed: 12/12/2022] Open
Abstract
Dysfunctional zinc signaling is implicated in disease processes including cardiovascular disease, Alzheimer's disease and diabetes. Of the twenty-four mammalian zinc transporters, ZIP7 has been identified as an important mediator of the ‘zinc wave’ and in cellular signaling. Utilizing siRNA targeting Zip7 mRNA we have identified that Zip7 regulates glucose metabolism in skeletal muscle cells. An siRNA targeting Zip7 mRNA down regulated Zip7 mRNA 4.6-fold (p = 0.0006) when compared to a scramble control. This was concomitant with a reduction in the expression of genes involved in glucose metabolism including Agl, Dlst, Galm, Gbe1, Idh3g, Pck2, Pgam2, Pgm2, Phkb, Pygm, Tpi1, Gusb and Glut4. Glut4 protein expression was also reduced and insulin-stimulated glycogen synthesis was decreased. This was associated with a reduction in the mRNA expression of Insr, Irs1 and Irs2, and the phosphorylation of Akt. These studies provide a novel role for Zip7 in glucose metabolism in skeletal muscle and highlight the importance of this transporter in contributing to glycaemic control in this tissue.
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Affiliation(s)
- Stephen A. Myers
- Collaborative Research Network and the School of Health Sciences, University of Ballarat, Mount Helen Campus, Victoria, Australia
- * E-mail:
| | - Alex Nield
- Collaborative Research Network and the School of Health Sciences, University of Ballarat, Mount Helen Campus, Victoria, Australia
| | - Guat-Siew Chew
- School of Health Sciences, University of Ballarat, Mount Helen Campus, Victoria, Australia
| | - Mark A. Myers
- Collaborative Research Network and the School of Health Sciences, University of Ballarat, Mount Helen Campus, Victoria, Australia
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Aas V, Bakke SS, Feng YZ, Kase ET, Jensen J, Bajpeyi S, Thoresen GH, Rustan AC. Are cultured human myotubes far from home? Cell Tissue Res 2013; 354:671-82. [PMID: 23749200 DOI: 10.1007/s00441-013-1655-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 05/03/2013] [Indexed: 12/25/2022]
Abstract
Satellite cells can be isolated from skeletal muscle biopsies, activated to proliferating myoblasts and differentiated into multinuclear myotubes in culture. These cell cultures represent a model system for intact human skeletal muscle and can be modulated ex vivo. The advantages of this system are that the most relevant genetic background is available for the investigation of human disease (as opposed to rodent cell cultures), the extracellular environment can be precisely controlled and the cells are not immortalized, thereby offering the possibility of studying innate characteristics of the donor. Limitations in differentiation status (fiber type) of the cells and energy metabolism can be improved by proper treatment, such as electrical pulse stimulation to mimic exercise. This review focuses on the way that human myotubes can be employed as a tool for studying metabolism in skeletal muscles, with special attention to changes in muscle energy metabolism in obesity and type 2 diabetes.
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Affiliation(s)
- Vigdis Aas
- Institute of Pharmacy and Biomedical Laboratory Science, Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, Oslo, Norway,
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Friedrichsen M, Birk JB, Richter EA, Ribel-Madsen R, Pehmøller C, Hansen BF, Beck-Nielsen H, Hirshman MF, Goodyear LJ, Vaag A, Poulsen P, Wojtaszewski JFP. Akt2 influences glycogen synthase activity in human skeletal muscle through regulation of NH₂-terminal (sites 2 + 2a) phosphorylation. Am J Physiol Endocrinol Metab 2013; 304:E631-9. [PMID: 23321478 PMCID: PMC3774094 DOI: 10.1152/ajpendo.00494.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Type 2 diabetes is characterized by reduced muscle glycogen synthesis. The key enzyme in this process, glycogen synthase (GS), is activated via proximal insulin signaling, but the exact molecular events remain unknown. Previously, we demonstrated that phosphorylation of Thr³⁰⁸ on Akt (p-Akt-Thr³⁰⁸), Akt2 activity, and GS activity in muscle were positively associated with insulin sensitivity. Here, in the same study population, we determined the influence of several upstream elements in the canonical PI3K signaling on muscle GS activation. One-hundred eighty-one nondiabetic twins were examined with the euglycemic hyperinsulinemic clamp combined with excision of muscle biopsies. Insulin signaling was evaluated at the levels of the insulin receptor, IRS-1-associated PI3K (IRS-1-PI3K), Akt, and GS employing activity assays and phosphospecific Western blotting. The insulin-stimulated GS activity was positively associated with p-Akt-Thr³⁰⁸ (P = 0.01) and Akt2 activity (P = 0.04) but not p-Akt-Ser⁴⁷³ or IRS-1-PI3K activity. Furthermore, p-Akt-Thr³⁰⁸ and Akt2 activity were negatively associated with NH₂-terminal GS phosphorylation (P = 0.001 for both), which in turn was negatively associated with insulin-stimulated GS activity (P < 0.001). We found no association between COOH-terminal GS phosphorylation and Akt or GS activity. Employing whole body Akt2-knockout mice, we validated the necessity for Akt2 in insulin-mediated GS activation. However, since insulin did not affect NH₂-terminal phosphorylation in mice, we could not use this model to validate the observed association between GS NH₂-terminal phosphorylation and Akt activity in humans. In conclusion, our study suggests that although COOH-terminal dephosphorylation is likely necessary for GS activation, Akt2-dependent NH₂-terminal dephosphorylation may be the site for "fine-tuning" insulin-mediated GS activation in humans.
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Montori-Grau M, Tarrats N, Osorio-Conles O, Orozco A, Serrano-Marco L, Vázquez-Carrera M, Gómez-Foix AM. Glucose dependence of glycogen synthase activity regulation by GSK3 and MEK/ERK inhibitors and angiotensin-(1-7) action on these pathways in cultured human myotubes. Cell Signal 2013; 25:1318-27. [PMID: 23453973 DOI: 10.1016/j.cellsig.2013.02.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 01/31/2013] [Accepted: 02/13/2013] [Indexed: 11/18/2022]
Abstract
Glycogen synthase (GS) is activated by glucose/glycogen depletion in skeletal muscle cells, but the contributing signaling pathways, including the chief GS regulator GSK3, have not been fully defined. The MEK/ERK pathway is known to regulate GSK3 and respond to glucose. The aim of this study was to elucidate the GSK3 and MEK/ERK pathway contribution to GS activation by glucose deprivation in cultured human myotubes. Moreover, we tested the glucose-dependence of GSK3 and MEK/ERK effects on GS and angiotensin (1-7) actions on these pathways. We show that glucose deprivation activated GS, but did not change phospho-GS (Ser640/1), GSK3β activity or activity-activating phosphorylation of ERK1/2. We then treated glucose-replete and -depleted cells with SB415286, U0126, LY294 and rapamycin to inhibit GSK3, MEK1/2, PI3K and mTOR, respectively. SB415286 activated GS and decreased the relative phospho-GS (Ser640/1) level, more in glucose-depleted than -replete cells. U0126 activated GS and reduced the phospho-GS (Ser640/1) content significantly in glucose-depleted cells, while GSK3β activity tended to increase. LY294 inactivated GS in glucose-depleted cells only, without affecting relative phospho-GS (Ser640/1) level. Rapamycin had no effect on GS activation. Angiotensin-(1-7) raised phospho-ERK1/2 but not phospho-GSK3β (Ser9) content, while it inactivated GS and increased GS phosphorylation on Ser640/1, in glucose-replete cells. In glucose-depleted cells, angiotensin-(1-7) effects on ERK1/2 and GS were reverted, while relative phospho-GSK3β (Ser9) content decreased. In conclusion, activation of GS by glucose deprivation is not due to GS Ser640/1 dephosphorylation, GSK3β or ERK1/2 regulation in cultured myotubes. However, glucose depletion enhances GS activation/Ser640/1 dephosphorylation due to both GSK3 and MEK/ERK inhibition. Angiotensin-(1-7) inactivates GS in glucose-replete cells in association with ERK1/2 activation, not with GSK3 regulation, and glucose deprivation reverts both hormone effects. Thus, the ERK1/2 pathway negatively regulates GS activity in myotubes, without involving GSK3 regulation, and as a function of the presence of glucose.
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Affiliation(s)
- Marta Montori-Grau
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM)-Instituto de Salud Carlos III, Spain.
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Abstract
Glucose disposal in skeletal muscle is a major target for insulin action and assessment of insulin-regulated glucose uptake under in vitro conditions allows the direct determination of insulin sensitivity in this organ. For this purpose, a variety of muscle preparations from different parts of the body can be used. We describe here a detailed protocol for using epitrochlearis muscle strips and additionally for using primary skeletal muscle cells.
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Kleinert M, Sylow L, Richter EA. Regulation of glycogen synthase in muscle and its role in Type 2 diabetes. ACTA ACUST UNITED AC 2013. [DOI: 10.2217/dmt.12.54] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Palm DC, Rohwer JM, Hofmeyr JHS. Regulation of glycogen synthase from mammalian skeletal muscle--a unifying view of allosteric and covalent regulation. FEBS J 2012; 280:2-27. [PMID: 23134486 DOI: 10.1111/febs.12059] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/29/2012] [Accepted: 11/05/2012] [Indexed: 12/27/2022]
Abstract
It is widely accepted that insufficient insulin-stimulated activation of muscle glycogen synthesis is one of the major components of non-insulin-dependent (type 2) diabetes mellitus. Glycogen synthase, a key enzyme in muscle glycogen synthesis, is extensively regulated, both allosterically (by glucose-6-phosphate, ATP, and others) and covalently (by phosphorylation). Although glycogen synthase has been a topic of intense study for more than 50 years, its kinetic characterization has been confounded by its large number of phosphorylation states. Questions remain regarding the function of glycogen synthase regulation and the relative importance of allosteric and covalent modification in fulfilling this function. In this review, we consider both earlier kinetic studies and more recent site-directed mutagenesis and crystal structure studies in a detailed qualitative discussion of the effects of regulation on the kinetics of glycogen synthase. We propose that both allosteric and covalent modification of glycogen synthase may be described by a Monod-Wyman-Changeux model in terms of apparent changes to L, the equilibrium constant for transition between the T and R conformers. As, with the exception of L, all parameters of this model are independent of the glycogen synthase phosphorylation state, the need to determine kinetic parameters for all possible states is eliminated; only the relationship between a particular state and L must be established. We conclude by suggesting that renewed efforts to characterize the relationship between phosphorylation and the kinetics of glycogen synthase are essential in order to obtain a better quantitative understanding of the function of glycogen synthesis regulation. The model we propose may prove useful in this regard.
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Affiliation(s)
- Daniel C Palm
- Triple J Group for Molecular Cell Physiology, Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa
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Nie J, Kong Z, Baker JS, Tong TK, Lei SH, Shi Q. Acute changes in glycemic homeostasis in response to brief high-intensity intermittent exercise in obese adults. J Exerc Sci Fit 2012. [DOI: 10.1016/j.jesf.2012.10.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Jensen J, Tantiwong P, Stuenæs JT, Molina-Carrion M, DeFronzo RA, Sakamoto K, Musi N. Effect of acute exercise on glycogen synthase in muscle from obese and diabetic subjects. Am J Physiol Endocrinol Metab 2012; 303:E82-9. [PMID: 22510711 PMCID: PMC3404561 DOI: 10.1152/ajpendo.00658.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin stimulates glycogen synthase (GS) through dephosphorylation of serine residues, and this effect is impaired in skeletal muscle from insulin-resistant [obese and type 2 diabetic (T2DM)] subjects. Exercise also increases GS activity, yet it is not known whether the ability of exercise to affect GS is impaired in insulin-resistant subjects. The objective of this study was to examine the effect of acute exercise on GS phosphorylation and enzyme kinetic properties in muscle from insulin-resistant individuals. Lean normal glucose-tolerant (NGT), obese NGT, and obese T2DM subjects performed 40 min of moderate-intensity cycle exercise (70% of Vo(2max)). GS kinetic properties and phosphorylation were measured in vastus lateralis muscle before exercise, immediately after exercise, and 3.5 h postexercise. In lean subjects, GS fractional activity increased twofold after 40 min of exercise, and it remained elevated after the 3.5-h rest period. Importantly, exercise also decreased GS K(m) for UDP-glucose from ≈0.5 to ≈0.2 mM. In lean subjects, exercise caused significant dephosphorylation of GS by 50-70% (Ser(641), Ser(645), and Ser(645,649,653,657)), and phosphorylation of these sites remained decreased after 3.5 h; Ser⁷ phosphorylation was not regulated by exercise. In obese NGT and T2DM subjects, exercise increased GS fractional activity, decreased K(m) for UDP-glucose, and decreased GS phosphorylation as effectively as in lean NGT subjects. We conclude that the molecular regulatory process by which exercise promotes glycogen synthesis in muscle is preserved in insulin-resistant subjects.
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Affiliation(s)
- Jørgen Jensen
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
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Biensø RS, Ringholm S, Kiilerich K, Aachmann-Andersen NJ, Krogh-Madsen R, Guerra B, Plomgaard P, van Hall G, Treebak JT, Saltin B, Lundby C, Calbet JAL, Pilegaard H, Wojtaszewski JFP. GLUT4 and glycogen synthase are key players in bed rest-induced insulin resistance. Diabetes 2012; 61:1090-9. [PMID: 22403297 PMCID: PMC3331744 DOI: 10.2337/db11-0884] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To elucidate the molecular mechanisms behind physical inactivity-induced insulin resistance in skeletal muscle, 12 young, healthy male subjects completed 7 days of bed rest with vastus lateralis muscle biopsies obtained before and after. In six of the subjects, muscle biopsies were taken from both legs before and after a 3-h hyperinsulinemic euglycemic clamp performed 3 h after a 45-min, one-legged exercise. Blood samples were obtained from one femoral artery and both femoral veins before and during the clamp. Glucose infusion rate and leg glucose extraction during the clamp were lower after than before bed rest. This bed rest-induced insulin resistance occurred together with reduced muscle GLUT4, hexokinase II, protein kinase B/Akt1, and Akt2 protein level, and a tendency for reduced 3-hydroxyacyl-CoA dehydrogenase activity. The ability of insulin to phosphorylate Akt and activate glycogen synthase (GS) was reduced with normal GS site 3 but abnormal GS site 2+2a phosphorylation after bed rest. Exercise enhanced insulin-stimulated leg glucose extraction both before and after bed rest, which was accompanied by higher GS activity in the prior-exercised leg than the rested leg. The present findings demonstrate that physical inactivity-induced insulin resistance in muscle is associated with lower content/activity of key proteins in glucose transport/phosphorylation and storage.
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Affiliation(s)
- Rasmus S Biensø
- Copenhagen Muscle Research Centre, University of Copenhagen, Copenhagen, Denmark.
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Lin FC, Bolling A, Stuenæs JT, Cumming KT, Ingvaldsen A, Lai YC, Ivy JL, Jensen J. Effect of insulin and contraction on glycogen synthase phosphorylation and kinetic properties in epitrochlearis muscles from lean and obese Zucker rats. Am J Physiol Cell Physiol 2012; 302:C1539-47. [PMID: 22403789 DOI: 10.1152/ajpcell.00430.2011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the present study, the effects of insulin and contraction on glycogen synthase (GS) kinetic properties and phosphorylation were investigated in epitrochlearis muscles from lean and obese Zucker rats. Total GS activity and protein expression were ~15% lower in epitrochlearis from obese rats compared with lean rats. Insulin-stimulated GS fractional activity and affinity for UDP-glucose were lower (higher K(m)) in muscles from obese rats. GS Ser(641) and Ser(645,649,653,657) phosphorylation was higher in insulin-stimulated muscles from obese rats, which agreed with lower GS activation. Contraction-mediated GS dephosphorylation of Ser(641), Ser(641+645), Ser(645,649,653,657), and Ser(7+10) was normal in muscles from obese Zucker rats, and GS fractional activity increased to similar levels in epitrochlearis muscles from lean and obese rats. GS affinity for UDP glucose was ~0.8, ~0.4, and ~0.1 mM with assay buffers containing 0, 0.17, and 12 mM glucose 6-phosphate, respectively. Contraction increased affinity for UDP-glucose (reduced K(m)) at a physiological concentration of glucose 6-phosphate (0.17 mM) to ~0.2 mM in muscles from both lean and obese rats. Interestingly, in the absence of glucose 6-phosphate in the assay buffer, contraction (and insulin) did not influence GS affinity for UDP-glucose, indicating that affinity is regulated by sensitivity for glucose 6-phosphate. In conclusion, contraction-mediated activation and dephosphorylation of GS were normal in muscles from obese Zucker rats, whereas insulin-mediated GS activation and dephosphorylation were impaired.
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Affiliation(s)
- Fang Chin Lin
- Department of Physical Performance, Norwegian School of Sport Sciences, P. O. Box 4014 Ullevål Stadion, N-0806 Oslo, Norway
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Nogales-Gadea G, Consuegra-García I, Rubio JC, Arenas J, Cuadros M, Camara Y, Torres-Torronteras J, Fiuza-Luces C, Lucia A, Martín MA, García-Arumí E, Andreu AL. A transcriptomic approach to search for novel phenotypic regulators in McArdle disease. PLoS One 2012; 7:e31718. [PMID: 22347505 PMCID: PMC3276513 DOI: 10.1371/journal.pone.0031718] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 01/14/2012] [Indexed: 12/20/2022] Open
Abstract
McArdle disease is caused by lack of glycogen phosphorylase (GP) activity in skeletal muscle. Patients experience exercise intolerance, presenting as early fatigue and contractures. In this study, we investigated the effects produced by a lack of GP on several genes and proteins of skeletal muscle in McArdle patients. Muscle tissue of 35 patients and 7 healthy controls were used to identify abnormalities in the patients' transcriptomic profile using low-density arrays. Gene expression was analyzed for the influence of variables such as sex and clinical severity. Differences in protein expression were studied by immunoblotting and 2D electrophoresis analysis, and protein complexes were examined by two-dimensional, blue native gel electrophoresis (BN-PAGE). A number of genes including those encoding acetyl-coA carboxylase beta, m-cadherin, calpain III, creatine kinase, glycogen synthase (GS), and sarcoplasmic reticulum calcium ATPase 1 (SERCA1), were found to be downregulated in patients. Specifically, compared to controls, GS and SERCA1 proteins were reduced by 50% and 75% respectively; also, unphosphorylated GS and SERCA1 were highly downregulated. On BN-PAGE analysis, GP was present with GS in two muscle protein complexes. Our findings revealed some issues that could be important in understanding the physiological consequences of McArdle disease: (i) SERCA1 downregulation in patients could result in impaired calcium transport in type II (fast-twitch) muscle fibers, leading to early fatigability during exercise tasks involving type II fibers (which mostly use glycolytic metabolism), i.e. isometric exercise, lifting weights or intense dynamic exercise (stair climbing, bicycling, walking at a very brisk pace), (ii) GP and GS were found together in two protein complexes, which suggests a new regulatory mechanism in the activity of these glycogen enzymes.
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Affiliation(s)
- Gisela Nogales-Gadea
- Departament de Patologia Mitocondrial i Neuromuscular, Hospital Universitari Vall d'Hebron, Institut de Recerca (VHIR), Universitat Autónoma de Barcelona, Barcelona, Spain
- Experimental Neurology Laboratory, Institut de Recerca HSCSP, Universitat Autònoma de Barcelona, Barcelona, Spain
- Spanish Network for Research in Rare diseases (CIBERER), Instituto de Salud Carlos III, Spain Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Inés Consuegra-García
- Spanish Network for Research in Rare diseases (CIBERER), Instituto de Salud Carlos III, Spain Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
- Unidad de Proteómica, Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Juan C. Rubio
- Spanish Network for Research in Rare diseases (CIBERER), Instituto de Salud Carlos III, Spain Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
- Unidad de Genómica, Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Joaquin Arenas
- Spanish Network for Research in Rare diseases (CIBERER), Instituto de Salud Carlos III, Spain Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Marc Cuadros
- Departament de Patologia Mitocondrial i Neuromuscular, Hospital Universitari Vall d'Hebron, Institut de Recerca (VHIR), Universitat Autónoma de Barcelona, Barcelona, Spain
- Spanish Network for Research in Rare diseases (CIBERER), Instituto de Salud Carlos III, Spain Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Yolanda Camara
- Departament de Patologia Mitocondrial i Neuromuscular, Hospital Universitari Vall d'Hebron, Institut de Recerca (VHIR), Universitat Autónoma de Barcelona, Barcelona, Spain
- Spanish Network for Research in Rare diseases (CIBERER), Instituto de Salud Carlos III, Spain Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Javier Torres-Torronteras
- Departament de Patologia Mitocondrial i Neuromuscular, Hospital Universitari Vall d'Hebron, Institut de Recerca (VHIR), Universitat Autónoma de Barcelona, Barcelona, Spain
- Spanish Network for Research in Rare diseases (CIBERER), Instituto de Salud Carlos III, Spain Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | | | | | - Miguel A. Martín
- Spanish Network for Research in Rare diseases (CIBERER), Instituto de Salud Carlos III, Spain Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
- Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Elena García-Arumí
- Departament de Patologia Mitocondrial i Neuromuscular, Hospital Universitari Vall d'Hebron, Institut de Recerca (VHIR), Universitat Autónoma de Barcelona, Barcelona, Spain
- Spanish Network for Research in Rare diseases (CIBERER), Instituto de Salud Carlos III, Spain Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
- * E-mail:
| | - Antoni L. Andreu
- Departament de Patologia Mitocondrial i Neuromuscular, Hospital Universitari Vall d'Hebron, Institut de Recerca (VHIR), Universitat Autónoma de Barcelona, Barcelona, Spain
- Spanish Network for Research in Rare diseases (CIBERER), Instituto de Salud Carlos III, Spain Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
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YANG Y, GUO J, KIM J, WANG M, CHAE B. Effects of growth rate on carcass and meat quality traits and their association with metabolism-related gene expression in finishing pigs. Anim Sci J 2012; 83:169-77. [DOI: 10.1111/j.1740-0929.2011.00929.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jensen J, Rustad PI, Kolnes AJ, Lai YC. The role of skeletal muscle glycogen breakdown for regulation of insulin sensitivity by exercise. Front Physiol 2011; 2:112. [PMID: 22232606 PMCID: PMC3248697 DOI: 10.3389/fphys.2011.00112] [Citation(s) in RCA: 219] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 12/09/2011] [Indexed: 12/12/2022] Open
Abstract
Glycogen is the storage form of carbohydrates in mammals. In humans the majority of glycogen is stored in skeletal muscles (∼500 g) and the liver (∼100 g). Food is supplied in larger meals, but the blood glucose concentration has to be kept within narrow limits to survive and stay healthy. Therefore, the body has to cope with periods of excess carbohydrates and periods without supplementation. Healthy persons remove blood glucose rapidly when glucose is in excess, but insulin-stimulated glucose disposal is reduced in insulin resistant and type 2 diabetic subjects. During a hyperinsulinemic euglycemic clamp, 70-90% of glucose disposal will be stored as muscle glycogen in healthy subjects. The glycogen stores in skeletal muscles are limited because an efficient feedback-mediated inhibition of glycogen synthase prevents accumulation. De novo lipid synthesis can contribute to glucose disposal when glycogen stores are filled. Exercise physiologists normally consider glycogen's main function as energy substrate. Glycogen is the main energy substrate during exercise intensity above 70% of maximal oxygen uptake ([Formula: see text]) and fatigue develops when the glycogen stores are depleted in the active muscles. After exercise, the rate of glycogen synthesis is increased to replete glycogen stores, and blood glucose is the substrate. Indeed insulin-stimulated glucose uptake and glycogen synthesis is elevated after exercise, which, from an evolutional point of view, will favor glycogen repletion and preparation for new "fight or flight" events. In the modern society, the reduced glycogen stores in skeletal muscles after exercise allows carbohydrates to be stored as muscle glycogen and prevents that glucose is channeled to de novo lipid synthesis, which over time will causes ectopic fat accumulation and insulin resistance. The reduction of skeletal muscle glycogen after exercise allows a healthy storage of carbohydrates after meals and prevents development of type 2 diabetes.
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Affiliation(s)
- Jørgen Jensen
- Department of Physical Performance, Norwegian School of Sport Sciences Oslo, Norway
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Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training. Eur J Appl Physiol 2011; 112:2767-75. [PMID: 22124524 DOI: 10.1007/s00421-011-2254-z] [Citation(s) in RCA: 165] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 11/16/2011] [Indexed: 02/07/2023]
Abstract
High-intensity interval training (HIT) has been proposed as a time-efficient alternative to traditional cardiorespiratory exercise training, but is very fatiguing. In this study, we investigated the effects of a reduced-exertion HIT (REHIT) exercise intervention on insulin sensitivity and aerobic capacity. Twenty-nine healthy but sedentary young men and women were randomly assigned to the REHIT intervention (men, n = 7; women, n = 8) or a control group (men, n = 6; women, n = 8). Subjects assigned to the control groups maintained their normal sedentary lifestyle, whilst subjects in the training groups completed three exercise sessions per week for 6 weeks. The 10-min exercise sessions consisted of low-intensity cycling (60 W) and one (first session) or two (all other sessions) brief 'all-out' sprints (10 s in week 1, 15 s in weeks 2-3 and 20 s in the final 3 weeks). Aerobic capacity ([Formula: see text]) and the glucose and insulin response to a 75-g glucose load (OGTT) were determined before and 3 days after the exercise program. Despite relatively low ratings of perceived exertion (RPE 13 ± 1), insulin sensitivity significantly increased by 28% in the male training group following the REHIT intervention (P < 0.05). [Formula: see text] increased in the male training (+15%) and female training (+12%) groups (P < 0.01). In conclusion we show that a novel, feasible exercise intervention can improve metabolic health and aerobic capacity. REHIT may offer a genuinely time-efficient alternative to HIT and conventional cardiorespiratory exercise training for improving risk factors of T2D.
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Hara D, Morrison PJ, Ding Z, Ivy JL. Effect of carbohydrate-protein supplementation postexercise on rat muscle glycogen synthesis and phosphorylation of proteins controlling glucose storage. Metabolism 2011; 60:1406-15. [PMID: 21489581 DOI: 10.1016/j.metabol.2011.02.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 02/08/2011] [Accepted: 02/10/2011] [Indexed: 11/16/2022]
Abstract
To examine whether addition of protein to a carbohydrate supplement enhances muscle glycogen synthesis, we compared the muscle glycogen concentrations of rats that had been depleted of their muscle glycogen stores with a 3-hour swim and immediately supplemented with a placebo (Con), carbohydrate (CHO), or carbohydrate plus protein supplement (C+P). Rats were given either 0.9 g carbohydrate per kilogram body mass for the CHO group or 0.9 g carbohydrate + 0.3 g protein per kilogram body mass for the C+P groups. Muscle samples of the red and white quadriceps were excised immediately, 30 minutes, or 90 minutes postexercise. Glycogen concentration of the C+P group was greater than that of the CHO group at 90 minutes postexercise in both red (C+P, 28.3 ± 2.6 µmol/g vs CHO, 22.4 ± 2.0 µmol/g; P < .05) and white (C+P, 24.9 ± 2.4 µmol/g vs CHO, 17.64 ± 1.5 µmol/g; P < .01) quadriceps. Protein kinase B phosphorylation was greater in the C+P-30 group (the number following treatment group abbreviation refers to time [in minutes] of euthanasia following exercise) than the sedentary control and exercised control groups in red quadriceps at 30 minutes and in white quadriceps at 90 minutes postexercise. This difference was not observed in the CHO group. Phosphorylation of glycogen synthase was significantly reduced 30 minutes postexercise and returned to baseline levels by 90 minutes postexercise in both CHO- and C+P-supplemented groups, with no difference between supplements. These results demonstrated that the addition of protein to a carbohydrate supplement will enhance the rate of muscle glycogen restoration postexercise and may involve facilitation of the glucose transport process.
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Affiliation(s)
- Daisuke Hara
- Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas, Austin, TX 78712, USA
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Ngubane PS, Masola B, Musabayane CT. The effects of Syzygium aromaticum-derived oleanolic acid on glycogenic enzymes in streptozotocin-induced diabetic rats. Ren Fail 2011; 33:434-9. [PMID: 21529273 DOI: 10.3109/0886022x.2011.568147] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Studies indicate that the antihyperglycemic effects of Syzygium aromaticum-derived oleanolic acid (OA) are mediated in part through increased hepatic glycogen synthesis. Accordingly, this study assessed the influence of OA on the activity of glucokinase (GK) and hexokinase (HK) of skeletal muscle and liver tissues in streptozotocin (STZ)-induced diabetic rats. After 5 weeks of OA treatment, hepatic and gastrocnemius muscle glycogen concentrations and activities of GK and HK were measured spectrophotometrically in reactions where the oxidation of glucose-6-phosphate (G-6-PDH) formed was coupled to nicotinamide adenine dinucleotide phosphate (NADP+) reduction catalyzed by G-6-PDH dehydrogenase. Rats treated with deionized water or standard hypoglycemic drugs acted as untreated and treated positive controls, respectively. STZ-induced diabetic rats exhibited depleted glycogen levels and low activities of glycogenic enzymes in muscle and hepatic tissues. OA administration restored these biochemical alterations to near normalcy. The combination of OA and insulin did not significantly alter the activities of HK and GK of STZ-induced diabetic rats, suggesting that glycogen synthesis can also occur from precursors such as amino acids or fructose and lactate. The attenuation of the activities of glycogenic enzymes with concomitant increases of hepatic and muscle glycogen concentrations of STZ-induced diabetic rats provides a therapeutic strategy for diabetes treatment.
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Affiliation(s)
- Phikelelani S Ngubane
- Department of Human PhysiologyFaculty of Health Science, School of Medical Sciences, University of KwaZulu-Natal, Durban, South Africa
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Brandon AE, Hoy AJ, Wright LE, Turner N, Hegarty BD, Iseli TJ, Julia Xu X, Cooney GJ, Saha AK, Ruderman NB, Kraegen EW. The evolution of insulin resistance in muscle of the glucose infused rat. Arch Biochem Biophys 2011; 509:133-41. [PMID: 21420928 DOI: 10.1016/j.abb.2011.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Revised: 03/14/2011] [Accepted: 03/15/2011] [Indexed: 11/17/2022]
Abstract
Glucose infusion into rats causes skeletal muscle insulin resistance that initially occurs without changes in insulin signaling. The aim of the current study was to prolong glucose infusion and evaluate other events associated with the transition to muscle insulin resistance. Hyperglycemia was produced in rats by glucose infusion for 3, 5 and 8 h. The rate of infusion required to maintain hyperglycemia was reduced at 5 and 8 h. Glucose uptake into red quadriceps (RQ) and its incorporation into glycogen decreased between 3 and 5 h, further decreasing at 8 h. The earliest observed change in RQ was decreased AMPKα2 activity associated with large increases in muscle glycogen content at 3 h. Activation of the mTOR pathway occurred at 5 h. Akt phosphorylation (Ser(473)) was decreased at 8 h compared to 3 and 5, although no decrease in phosphorylation of downstream GSK-3β (Ser(9)) and AS160 (Thr(642)) was observed. White quadriceps showed a similar but delayed pattern, with insulin resistance developing by 8 h and decreased AMPKα2 activity at 5 h. These results indicate that, in the presence of a nutrient overload, alterations in muscle insulin signaling occur, but after insulin resistance develops and appropriate changes in energy/nutrient sensing pathways occur.
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Affiliation(s)
- Amanda E Brandon
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia.
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Jensen J, Ruge T, Lai YC, Svensson MK, Eriksson JW. Effects of adrenaline on whole-body glucose metabolism and insulin-mediated regulation of glycogen synthase and PKB phosphorylation in human skeletal muscle. Metabolism 2011; 60:215-26. [PMID: 20153492 DOI: 10.1016/j.metabol.2009.12.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 12/23/2009] [Accepted: 12/28/2009] [Indexed: 11/20/2022]
Abstract
In the present study, we investigated the effect of adrenaline on insulin-mediated regulation of glucose and fat metabolism with focus on regulation of skeletal muscle PKB, GSK-3, and glycogen synthase (GS) phosphorylation. Ten healthy subjects (5 men and 5 women) received a 240-minute intravenous infusion of adrenaline (0.05 μg/[kg min]) or saline; after 120 minutes, a hyperinsulinemic-euglycemic clamp was added. Adrenaline infusion increased blood glucose concentration by approximately 50%, but the hyperinsulinemic clamp normalized blood glucose within 30 minutes. Glucose infusion rate during the last hour was approximately 60% lower during adrenaline infusion compared with saline (4.3 ± 0.5 vs 11.2 ± 0.6 mg/kg lean body mass per minute). Insulin increased PKB Ser⁴⁷³, PKB Thr³⁰⁸, and GSK-3β Ser⁹ phosphorylation in skeletal muscles; coinfusion of adrenaline did not influence insulin-stimulated PKB and GSK-3 phosphorylation. Adrenaline alone did not influence phosphorylation of PKB and GSK-3β. Insulin increased GS fractional activity and decreased GS Ser⁶⁴¹ and Ser⁶⁴⁵,⁶⁴⁹,⁶⁵³,⁶⁵⁷ phosphorylation. In the presence of adrenaline, insulin did neither activate GS nor dephosphorylate GS Ser⁶⁴¹. Surprisingly, GS Ser⁷ phosphorylation was not influenced by adrenaline. Adrenaline increased plasma lactate concentration; and muscle glycogen content was reduced in skeletal muscle the day after adrenaline infusion, supporting that insulin does not stimulate glycogen synthesis in skeletal muscles when adrenaline is present. In conclusion, adrenaline did not influence basal or insulin-stimulated PKB and GSK-3β phosphorylation in muscles, but completely blocked insulin-mediated GS activation and Ser⁶⁴¹ dephosphorylation. Still, insulin normalized adrenaline-mediated hyperglycemia.
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Affiliation(s)
- Jørgen Jensen
- Department of Physiology, National Institute of Occupational Health, P.O. Box 8149 Dep, N-0033 Oslo, Norway.
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Berman Y, North KN. A gene for speed: the emerging role of alpha-actinin-3 in muscle metabolism. Physiology (Bethesda) 2010; 25:250-9. [PMID: 20699471 DOI: 10.1152/physiol.00008.2010] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A common polymorphism (R577X) in the ACTN3 gene results in complete deficiency of alpha-actinin-3 protein in approximately 16% of humans worldwide. The presence of alpha-actinin-3 protein is associated with improved sprint/power performance in athletes and the general population. Despite this, there is evidence that the null genotype XX has been acted on by recent positive selection, likely due to its emerging role in the regulation of muscle metabolism. alpha-Actinin-3 deficiency reduces the activity of glycogen phosphorylase and results in a fundamental shift toward more oxidative pathways of energy utilization.
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Affiliation(s)
- Yemima Berman
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia
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