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Bederman IR, Lai N, Shuster J, Henderson L, Ewart S, Cabrera ME. Chronic hindlimb suspension unloading markedly decreases turnover rates of skeletal and cardiac muscle proteins and adipose tissue triglycerides. J Appl Physiol (1985) 2015; 119:16-26. [PMID: 25930021 DOI: 10.1152/japplphysiol.00004.2014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 04/25/2015] [Indexed: 11/22/2022] Open
Abstract
We previously showed that a single bolus of "doubly-labeled" water ((2)H2 (18)O) can be used to simultaneously determine energy expenditure and turnover rates (synthesis and degradation) of tissue-specific lipids and proteins by modeling labeling patterns of protein-bound alanine and triglyceride-bound glycerol (Bederman IR, Dufner DA, Alexander JC, Previs SF. Am J Physiol Endocrinol Metab 290: E1048-E1056, 2006). Using this novel method, we quantified changes in the whole body and tissue-specific energy balance in a rat model of simulated "microgravity" induced by hindlimb suspension unloading (HSU). After chronic HSU (3 wk), rats exhibited marked atrophy of skeletal and cardiac muscles and significant decrease in adipose tissue mass. For example, soleus muscle mass progressively decreased 11, 43, and 52%. We found similar energy expenditure between control (90 ± 3 kcal · kg(-1)· day(-1)) and hindlimb suspended (81 ± 6 kcal/kg day) animals. By comparing food intake (∼ 112 kcal · kg(-1) · day(-1)) and expenditure, we found that animals maintained positive calorie balance proportional to their body weight. From multicompartmental fitting of (2)H-labeling patterns, we found significantly (P < 0.005) decreased rates of synthesis (percent decrease from control: cardiac, 25.5%; soleus, 70.3%; extensor digitorum longus, 44.9%; gastrocnemius, 52.5%; and adipose tissue, 39.5%) and rates of degradation (muscles: cardiac, 9.7%; soleus, 52.0%; extensor digitorum longus, 27.8%; gastrocnemius, 37.4%; and adipose tissue, 50.2%). Overall, HSU affected growth of young rats by decreasing the turnover rates of proteins in skeletal and cardiac muscles and adipose tissue triglycerides. Specifically, we found that synthesis rates of skeletal and cardiac muscle proteins were affected to a much greater degree compared with the decrease in degradation rates, resulting in large negative balance and significant tissue loss. In contrast, we found a small decrease in adipose tissue triglyceride synthesis paired with a large decrease in degradation, resulting in smaller negative energy balance and loss of fat mass. We conclude that HSU in rats differentially affects turnover of muscle proteins vs. adipose tissue triglycerides.
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Affiliation(s)
| | - Nicola Lai
- Department of Pediatrics and Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | | | | | | | - Marco E Cabrera
- Department of Pediatrics and Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
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2
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Bamman MM, Cooper DM, Booth FW, Chin ER, Neufer PD, Trappe S, Lightfoot JT, Kraus WE, Joyner MJ. Exercise biology and medicine: innovative research to improve global health. Mayo Clin Proc 2014; 89:148-53. [PMID: 24485128 PMCID: PMC3972063 DOI: 10.1016/j.mayocp.2013.11.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/20/2013] [Accepted: 11/14/2013] [Indexed: 01/11/2023]
Affiliation(s)
- Marcas M Bamman
- UAB Center for Exercise Medicine and Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham.
| | - Dan M Cooper
- Department of Pediatrics and Institute for Clinical and Translational Science, University of California, Irvine
| | - Frank W Booth
- Department of Biomedical Sciences, Department of Medical Pharmacology and Physiology, and Department of Nutrition and Exercise Physiology, University of Missouri, Columbia
| | - Eva R Chin
- Department of Kinesiology, School of Public Health, University of Maryland, College Park
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, Department of Physiology, and Department of Kinesiology, East Carolina University, Greenville, NC
| | - Scott Trappe
- Human Performance Laboratory, Ball State University, Muncie, IN
| | - J Timothy Lightfoot
- Sydney and J. L. Huffines Institute for Sports Medicine and Human Performance, Texas A&M University, College Station
| | - William E Kraus
- Division of Cardiology, Department of Medicine, Duke University, Durham, NC
| | - Michael J Joyner
- Department of Anesthesiology, Mayo Clinic College of Medicine, Rochester, MN
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3
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Stevens L, Bastide B, Hedou J, Cieniewski-Bernard C, Montel V, Cochon L, Dupont E, Mounier Y. Potential regulation of human muscle plasticity by MLC2 post-translational modifications during bed rest and countermeasures. Arch Biochem Biophys 2013; 540:125-32. [DOI: 10.1016/j.abb.2013.10.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 10/08/2013] [Accepted: 10/21/2013] [Indexed: 10/26/2022]
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Vendelbo MH, Clasen BFF, Treebak JT, Møller L, Krusenstjerna-Hafstrøm T, Madsen M, Nielsen TS, Stødkilde-Jørgensen H, Pedersen SB, Jørgensen JOL, Goodyear LJ, Wojtaszewski JFP, Møller N, Jessen N. Insulin resistance after a 72-h fast is associated with impaired AS160 phosphorylation and accumulation of lipid and glycogen in human skeletal muscle. Am J Physiol Endocrinol Metab 2012; 302:E190-200. [PMID: 22028408 PMCID: PMC4971894 DOI: 10.1152/ajpendo.00207.2011] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During fasting, human skeletal muscle depends on lipid oxidation for its energy substrate metabolism. This is associated with the development of insulin resistance and a subsequent reduction of insulin-stimulated glucose uptake. The underlying mechanisms controlling insulin action on skeletal muscle under these conditions are unresolved. In a randomized design, we investigated eight healthy subjects after a 72-h fast compared with a 10-h overnight fast. Insulin action on skeletal muscle was assessed by a hyperinsulinemic euglycemic clamp and by determining insulin signaling to glucose transport. In addition, substrate oxidation, skeletal muscle lipid content, regulation of glycogen synthesis, and AMPK signaling were assessed. Skeletal muscle insulin sensitivity was reduced profoundly in response to a 72-h fast and substrate oxidation shifted to predominantly lipid oxidation. This was associated with accumulation of both lipid and glycogen in skeletal muscle. Intracellular insulin signaling to glucose transport was impaired by regulation of phosphorylation at specific sites on AS160 but not TBC1D1, both key regulators of glucose uptake. In contrast, fasting did not impact phosphorylation of AMPK or insulin regulation of Akt, both of which are established upstream kinases of AS160. These findings show that insulin resistance in muscles from healthy individuals is associated with suppression of site-specific phosphorylation of AS160, without Akt or AMPK being affected. This impairment of AS160 phosphorylation, in combination with glycogen accumulation and increased intramuscular lipid content, may provide the underlying mechanisms for resistance to insulin in skeletal muscle after a prolonged fast.
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Affiliation(s)
| | - B. F. F. Clasen
- Departments of 1Internal Medicine and Endocrinology and
- 2Clinical Pharmacology, Aarhus University Hospital, Aarhus;
| | - J. T. Treebak
- 3Molecular Physiology Group, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen;
| | - L. Møller
- Departments of 1Internal Medicine and Endocrinology and
| | | | - M. Madsen
- Departments of 1Internal Medicine and Endocrinology and
| | - T. S. Nielsen
- Departments of 1Internal Medicine and Endocrinology and
- 2Clinical Pharmacology, Aarhus University Hospital, Aarhus;
| | | | | | | | - L. J. Goodyear
- 5Joslin Diabetes Center and Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | - J. F. P. Wojtaszewski
- 3Molecular Physiology Group, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen;
| | - N. Møller
- Departments of 1Internal Medicine and Endocrinology and
| | - N. Jessen
- Departments of 1Internal Medicine and Endocrinology and
- 2Clinical Pharmacology, Aarhus University Hospital, Aarhus;
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Pravda J. Crohn's disease: evidence for involvement of unregulated transcytosis in disease etio-pathogenesis. World J Gastroenterol 2011; 17:1416-26. [PMID: 21472099 PMCID: PMC3070014 DOI: 10.3748/wjg.v17.i11.1416] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 12/11/2010] [Accepted: 12/18/2010] [Indexed: 02/06/2023] Open
Abstract
Crohn's disease (CD) is a chronic inflammatory bowel disease. Research has identified genetic predisposition and environmental factors as key elements in the development of the disease. However, the precise mechanism that initiates immune activation remains undefined. One pathway for luminal antigenic molecules to enter the sterile lamina propria and activate an immune response is via transcytosis. Transcytosis, although tightly regulated by the cell, has the potential for transepithelial transport of bacteria and highly antigenic luminal molecules whose uncontrolled translocation into the lamina propria can be the source of immune activation. Viewed as a whole, the evidence suggests that unregulated intestinal epithelial transcytosis is involved in the inappropriate presentation of immunogenic luminal macromolecules to the intestinal lamina propria. Thus fulfilling the role of an early pre-morbid mechanism that can result in antigenic overload of the lamina propria and initiate an immune response culminating in chronic inflammation characteristic of this disease. It is the aim of this paper to present evidence implicating enterocyte transcytosis in the early etio-pathogenesis of CD.
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Abstract
Functional ageing processes are characterized by a loss of performance capabilities regarding coordination, flexibility, strength, speed, and endurance. The effects of ageing processes on the cardiovascular system and skeletal muscle are the foci of attention. After age 30, the maximum aerobic dynamic performance capacity decreases by an average of 8% per decade. The causes are mainly a reduction in the maximum cardiac output and decreases in capillarization and in the skeletal muscle mass. An improvement in the maximum oxygen uptake by 18% and in the aerobic-anaerobic threshold by 22% was achieved in untrained men aged 55-70 years, in a 12-week-long bicycle ergometer-training programme. The strength of the skeletal muscle decreases particularly after 50-60 years of age. The main cause is the reduction in the number of motor units and muscle fibres. Further, modifications of the endothelial function and the development of sarcopenia are of particular importance in ageing processes. General aerobic dynamic training can improve the endothelial function in old age and thus help prevent cardiovascular diseases. Strength training is most appropriate for the prevention of sarcopenia. Imaging techniques over the last 20 years have provided new findings on the influence and the significance of physical activity on the brain. We call this new interdisciplinary area 'Exercise Neuroscience'. Demands on coordination and aerobic dynamic endurance are suitable in counteracting age-related neuronal cellular loss, synapsis hypotrophy, and in improving neurogenesis and capillarization. Adjusted physical activity is thus capable of counteracting age-related changes and performance loss not only in the cardiovascular system but also in the brain.
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Abstract
Although it appeared relatively suddenly, the current obesity epidemic - largely manifest in industrialized societies but now spreading to the rest of the world - is the result of interaction between human biology and human culture over the long period of human evolution. As mammals and primates, humans have the capacity to store body fat when opportunities to consume excess energy arise. But during the millions of years of human evolution such opportunities were rare and transient. More commonly ancestral hominins and modern humans were confronted with food scarcity and had to engage in high levels of physical activity. In tandem with encephalization, humans evolved elaborate and complex genetic and physiological systems to protect against starvation and defend stored body fat. They also devised technological aids for increasing energy consumption and reducing physical effort. In the last century, industrialization provided access to great quantities of mass-produced, high-calorie foods and many labour-saving and transportation devices, virtually abolishing starvation and heavy manual work. In the modern obesogenic environment, individuals possessing the appropriate combination of ancestral energy-conserving genes are at greater risk for overweight and obesity and associated chronic diseases.
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Affiliation(s)
- A Bellisari
- Department of Sociology and Anthropology, Lifespan Health Research Center, Wright State University, Dayton, OH 45435, USA.
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Muscle-Specific PPARbeta/delta Agonism May Provide Synergistic Benefits with Life Style Modifications. PPAR Res 2008; 2007:30578. [PMID: 18274626 PMCID: PMC2220041 DOI: 10.1155/2007/30578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Revised: 08/08/2007] [Accepted: 11/13/2007] [Indexed: 11/26/2022] Open
Abstract
Peroxisome proliferator-activated receptor β/δ
(PPARβ/δ)
has emerged as a powerful metabolic regulator in diverse tissues
including fat, skeletal muscle, and the heart. It is now
established that activation of
PPARβ/δ
promotes fatty acid oxidation in several tissues, such as skeletal
muscle and adipose tissue. In muscle,
PPARβ/δ
appears to act as a central regulator of fatty acid catabolism.
PPARβ/δ contents are increased in muscle during physiological situations
such as physical exercise or long-term fasting, characterized by
increased fatty acid oxidation. Targeted expression of an
activated form of PPARβ/δ
in skeletal muscle induces a switch to form increased numbers of
type I muscle fibers resembling the fiber type transition by
endurance training. Activation of
PPARβ/δ
also enhances mitochondrial capacity and fat oxidation in the
skeletal muscle that resembles the effect of regular exercise.
Therefore, it is hypothesized that muscle-specific
PPARβ/δ
agonists could be a key strategy to support the poor
cardiorespiratory fitness associated with metabolic disorders.
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Krochmal DJ, Kuzon WM, Urbanchek MG. Muscle force and power following tendon repair at altered tendon length. J Surg Res 2007; 146:81-9. [PMID: 17961595 DOI: 10.1016/j.jss.2007.04.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 04/06/2007] [Accepted: 04/16/2007] [Indexed: 11/26/2022]
Abstract
BACKGROUND While a great deal is known regarding the performance of muscle with intact tendon, little is known about muscle performance when tendon is surgically lengthened or shortened. This knowledge may allow surgeons to more accurately predict functional outcome following tendon repair when correcting a simple tendon laceration or performing a more complex vascularized neuromuscular transfer. MATERIALS AND METHODS We studied muscle performance 12 wk following extensor tendon repairs producing altered tendon lengths. Forty male Fischer 344 rats underwent division of the proximal and distal tendons of the extensor digitorum longus muscle. Tendons were immediately repaired producing tendons with increased length, decreased length, or presurgical length (control). Observation confirmed that altered tendon length produced inverse changes in initial resting muscle tension. RESULTS Muscle in the decreased tendon length group demonstrated a 15.2% greater muscle mass, 4.9% greater muscle length, 9.6% greater physiological cross-sectional area, 12.6% greater maximum isometric force, and 31.9% greater maximum power relative to the control tendon length group (P < 0.05). The increased tendon length group did not differ significantly from the control tendon length group for any measurement. Histologically, muscles set with a decreased tendon length demonstrated normal appearing hypertrophied fibers, without evidence of detrimental histological effects such as fibrosis, denervation, necrosis, inflammation, fiber type changes, or fiber splitting. CONCLUSION These data support the clinical practice of setting muscles with increased passive tension when performing tendon transfer surgeries. Conversely, setting muscles with decreased tension does not necessarily result in a force or power deficit.
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Affiliation(s)
- Daniel J Krochmal
- Section of Plastic Surgery, Department of Surgery, University of Michigan, Ann Arbor, Michigan, USA
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Hesselink MKC, van Baak MA. Physical activity and health, novel concepts and new targets: report from the 12th Conference of the International Research Group on the Biochemistry of Exercise. Proc Nutr Soc 2007; 63:189-97. [PMID: 15294029 DOI: 10.1079/pns2004353] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The present paper is the introductory paper to a series of brief reviews representing the proceedings of a recent conference on ‘The biochemical basis for the health effects of exercise’ organized by the International Research Group on the Biochemistry of Exercise in conjunction with the Nutrition Society. Here the aim is to briefly review and highlight the main innovations presented during this meeting. The following topics were covered during the meeting: exercise signalling pathways controlling fuel oxidation during and after exercise; the fatty acid transporters of skeletal muscle; mechanisms involved in exercise-induced mitochondrial biogenesis in skeletal muscle; new methodologies and insights in the regulation of fat metabolism during exercise; muscle hypertrophy: the signals of insulin, amino acids and exercise; adipose tissue–liver–muscle interactions leading to insulin resistance. In these symposia state-of-the-art knowledge on how physical exercise exerts its effects on health was presented. The fast-growing number of identified pathways and processes involved in the health effects of physical exercise, which were discussed during the meeting, will help to develop tailored physical-activity regimens in the prevention of inactivity-induced deterioration of health.
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Affiliation(s)
- Matthijs K C Hesselink
- Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.
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Mortensen OH, Frandsen L, Schjerling P, Nishimura E, Grunnet N. PGC-1alpha and PGC-1beta have both similar and distinct effects on myofiber switching toward an oxidative phenotype. Am J Physiol Endocrinol Metab 2006; 291:E807-16. [PMID: 16720625 DOI: 10.1152/ajpendo.00591.2005] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Peroxisome proliferator-activated receptor-gamma coactivator-1alpha and -1beta (PGC-1alpha and PGC-1beta) were overexpressed by adenovirus-mediated gene transfer in cultures of primary rat skeletal muscle cells derived from neonatal myoblasts. Effects on muscle fiber type transition and metabolism were studied from days 5 to 22 of culture. PGC-1alpha and PGC-1beta overexpression caused a three- to fourfold increase in mRNA level, a doubling of enzymatic activity of citrate synthase, a slight increase in short-chain acyl-CoA dehydrogenase mRNA, a doubling of the mRNA level, and a 30-50% increase in enzymatic activity of glyceraldehyde-3-phosphate dehydrogenase. Lactate dehydrogenase or creatine kinase activity was unchanged. PGC-1alpha enhanced glycogen buildup twofold at 5 or 25 mM glucose, whereas PGC-1beta caused a decrease. Both PGC-1alpha and PGC-1beta overexpression caused a faster maturation of myotubes, as seen by mRNA downregulation of the immature embryonal and perinatal myosin heavy-chain (MHC) isoforms. PGC-1alpha or PGC-1beta overexpression enhanced mRNA of the slow oxidative-associated MHC isoform MHCIb and downregulated mRNA levels of the fast glycolytic-associated MHC isoforms MHCIIX and MHCIIB. Only PGC-1beta overexpression caused an increase in mRNA of the intermediary fast oxidative-associated MHC isoform MHCIIA. PGC-1alpha or PGC-1beta overexpression upregulated GLUT4 mRNA and downregulated myocyte enhancer factor 2C transcription factor mRNA; only PGC-1alpha overexpression caused an increase in the mRNA expression of TRB3, a negative regulator of insulin signaling. These results show that both PGC-1alpha and PGC-1beta are involved in the regulation of skeletal muscle fiber transition and metabolism and that they have both overlapping and differing effects.
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MESH Headings
- Animals
- Animals, Newborn
- Blotting, Northern
- Cells, Cultured
- Energy Metabolism/physiology
- Glucose Transporter Type 4/biosynthesis
- Glucose Transporter Type 4/genetics
- Glycogen/metabolism
- MEF2 Transcription Factors
- Muscle Contraction/physiology
- Muscle Fibers, Skeletal/enzymology
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/metabolism
- Myogenic Regulatory Factors/biosynthesis
- Myogenic Regulatory Factors/genetics
- Myosin Heavy Chains/genetics
- Myosin Heavy Chains/metabolism
- Oxidation-Reduction
- Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
- Protein Kinases/biosynthesis
- Protein Kinases/genetics
- Protein Serine-Threonine Kinases/antagonists & inhibitors
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- RNA-Binding Proteins/biosynthesis
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Rats
- Rats, Wistar
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription Factors/biosynthesis
- Transcription Factors/genetics
- Transcription Factors/metabolism
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Affiliation(s)
- Ole Hartvig Mortensen
- Department of Medical Biochemistry and Genetics, University of Copenhagen, Blegdamsvej 3, Bldg. 6.5, DK-2200 N, Denmark
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