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Stokie JR, Abbott G, Howlett KF, Hamilton DL, Shaw CS. Intramuscular lipid utilization during exercise: a systematic review, meta-analysis, and meta-regression. J Appl Physiol (1985) 2023; 134:581-592. [PMID: 36656983 DOI: 10.1152/japplphysiol.00637.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Intramuscular lipid (IMCL) utilization during exercise was controversial as numerous studies did not observe a decline in IMCL content post-exercise when assessed in muscle biopsies using biochemical techniques. Contemporary techniques including immunofluorescence microscopy and 1H-magnetic resonance spectroscopy (1H-MRS) offer advantages over biochemical techniques. The primary aim of this systematic review, meta-analysis, and meta-regression was to examine the net degradation of IMCL in response to an acute bout of cycling exercise in humans, as assessed with different analytical approaches. A secondary aim was to explore the factors influencing IMCL degradation including feeding status, exercise variables, and participant characteristics. A total of 44 studies met the inclusion criteria using biochemical, immunofluorescence, and 1H-MRS techniques. A meta-analysis was completed using a random effects model and percentage change in IMCL content calculated from the standardized mean difference. Cycling exercise resulted in a net degradation of IMCL regardless of technique (total effect -23.7%, 95% CI = -28.7 to -18.7%) and there was no difference when comparing fasted versus fed-state exercise (P > 0.05). IMCL degradation using immunofluorescence techniques detected larger effects in type I fibers compared with whole muscle using biochemical techniques (P = 0.003) and in type I fibers compared with type II fibers (P < 0.001). Although IMCL degradation was associated with exercise duration, V̇o2max, and BMI, none of these factors independently related to the change in IMCL content. These findings provide strong evidence that the analytical approach can influence the assessment of IMCL degradation in human skeletal muscle in response to exercise.
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Affiliation(s)
- Jayden R Stokie
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Gavin Abbott
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Kirsten F Howlett
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - David L Hamilton
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Christopher S Shaw
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
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Koenig AM, Koehler U, Hildebrandt O, Schwarzbach H, Hannemann L, Boneberg R, Heverhagen JT, Mahnken AH, Keller M, Kann PH, Deigner HP, Laur N, Kinscherf R, Hildebrandt W. The Effect of Obstructive Sleep Apnea and Continuous Positive Airway Pressure Therapy on Skeletal Muscle Lipid Content in Obese and Nonobese Men. J Endocr Soc 2021; 5:bvab082. [PMID: 34268461 PMCID: PMC8274947 DOI: 10.1210/jendso/bvab082] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Indexed: 01/01/2023] Open
Abstract
Obstructive sleep apnea (OSA), independently of obesity (OBS), predisposes to insulin resistance (IR) for largely unknown reasons. Because OSA-related intermittent hypoxia triggers lipolysis, overnight increases in circulating free fatty acids (FFAs) including palmitic acid (PA) may lead to ectopic intramuscular lipid accumulation potentially contributing to IR. Using 3-T-1H-magnetic resonance spectroscopy, we therefore compared intramyocellular and extramyocellular lipid (IMCL and EMCL) in the vastus lateralis muscle at approximately 7 am between 26 male patients with moderate-to-severe OSA (17 obese, 9 nonobese) and 23 healthy male controls (12 obese, 11 nonobese). Fiber type composition was evaluated by muscle biopsies. Moreover, we measured fasted FFAs including PA, glycated hemoglobin A1c, thigh subcutaneous fat volume (ScFAT, 1.5-T magnetic resonance tomography), and maximal oxygen uptake (VO2max). Fourteen patients were reassessed after continuous positive airway pressure (CPAP) therapy. Total FFAs and PA were significantly (by 178% and 166%) higher in OSA patients vs controls and correlated with the apnea-hypopnea index (AHI) (r ≥ 0.45, P < .01). Moreover, IMCL and EMCL were 55% (P < .05) and 40% (P < .05) higher in OSA patients, that is, 114% and 103% in nonobese, 24.4% and 8.4% in obese participants (with higher control levels). Overall, PA, FFAs (minus PA), and ScFAT significantly contributed to IMCL (multiple r = 0.568, P = .002). CPAP significantly decreased EMCL (–26%) and, by trend only, IMCL, total FFAs, and PA. Muscle fiber composition was unaffected by OSA or CPAP. Increases in IMCL and EMCL are detectable at approximately 7 am in OSA patients and are partly attributable to overnight FFA excesses and high ScFAT or body mass index. CPAP decreases FFAs and IMCL by trend but significantly reduces EMCL.
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Affiliation(s)
- Alexander M Koenig
- Department of Diagnostic and Interventional Radiology, University Hospital of Marburg, Philipps-University of Marburg, 35043 Marburg, Germany
| | - Ulrich Koehler
- Department of Sleep Medicine, Division of Pneumology, Internal Medicine, University Hospital, Philipps-University of Marburg, 35043 Marburg, Germany
| | - Olaf Hildebrandt
- Department of Sleep Medicine, Division of Pneumology, Internal Medicine, University Hospital, Philipps-University of Marburg, 35043 Marburg, Germany
| | - Hans Schwarzbach
- Department of Medical Cell Biology, Institute for Anatomy and Cell Biology, Philipps-University of Marburg, 35032 Marburg, Germany
| | - Lena Hannemann
- Department of Medical Cell Biology, Institute for Anatomy and Cell Biology, Philipps-University of Marburg, 35032 Marburg, Germany
| | - Raphael Boneberg
- Department of Medical Cell Biology, Institute for Anatomy and Cell Biology, Philipps-University of Marburg, 35032 Marburg, Germany
| | - Johannes T Heverhagen
- Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
| | - Andreas H Mahnken
- Department of Diagnostic and Interventional Radiology, University Hospital of Marburg, Philipps-University of Marburg, 35043 Marburg, Germany
| | - Malte Keller
- Department of Diagnostic and Interventional Radiology, University Hospital of Marburg, Philipps-University of Marburg, 35043 Marburg, Germany
| | - Peter H Kann
- Division of Endocrinology, Diabetology and Osteology, Internal Medicine, University Hospital, Philipps-University of Marburg, 35043 Marburg, Germany
| | - Hans-Peter Deigner
- Furtwangen University, Institute of Precision Medicine, 78054 VS-Schwenningen, Germany
| | - Nico Laur
- Department of Medical Cell Biology, Institute for Anatomy and Cell Biology, Philipps-University of Marburg, 35032 Marburg, Germany.,Furtwangen University, Institute of Precision Medicine, 78054 VS-Schwenningen, Germany
| | - Ralf Kinscherf
- Department of Medical Cell Biology, Institute for Anatomy and Cell Biology, Philipps-University of Marburg, 35032 Marburg, Germany
| | - Wulf Hildebrandt
- Department of Medical Cell Biology, Institute for Anatomy and Cell Biology, Philipps-University of Marburg, 35032 Marburg, Germany
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Seibert JT, Najt CP, Heden TD, Mashek DG, Chow LS. Muscle Lipid Droplets: Cellular Signaling to Exercise Physiology and Beyond. Trends Endocrinol Metab 2020; 31:928-938. [PMID: 32917515 PMCID: PMC7704552 DOI: 10.1016/j.tem.2020.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 07/09/2020] [Accepted: 08/13/2020] [Indexed: 12/21/2022]
Abstract
Conventionally viewed as energy storage depots, lipid droplets (LDs) play a central role in muscle lipid metabolism and intracellular signaling, as recognized by recent advances in our biological understanding. Specific subpopulations of muscle LDs, defined by location and associated proteins, are responsible for distinct biological functions. In this review, the traditional view of muscle LDs is examined, and the emerging role of LDs in intracellular signaling is highlighted. The effects of chronic and acute exercise on muscle LD metabolism and signaling is discussed. In conclusion, future directions for muscle LD research are identified. The primary focus will be on human studies, with inclusion of select animal/cellular/non-muscle studies as appropriate, to provide the underlying mechanisms driving the observed findings.
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Affiliation(s)
- Jacob T Seibert
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Charles P Najt
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Timothy D Heden
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Douglas G Mashek
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, Minneapolis, MN 55455, USA
| | - Lisa S Chow
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, Minneapolis, MN 55455, USA.
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Tobias IS, Galpin AJ. Moving human muscle physiology research forward: an evaluation of fiber type-specific protein research methodologies. Am J Physiol Cell Physiol 2020; 319:C858-C876. [DOI: 10.1152/ajpcell.00107.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Human skeletal muscle is a heterogeneous tissue composed of multiple fiber types that express unique contractile and metabolic properties. While analysis of mixed fiber samples predominates and holds value, increasing attention has been directed toward studying proteins segregated by fiber type, a methodological distinction termed “fiber type-specific.” Fiber type-specific protein studies have the advantage of uncovering key molecular effects that are often missed in mixed fiber homogenate studies but also require greater time and resource-intensive methods, particularly when applied to human muscle. This review summarizes and compares current methods used for fiber type-specific protein analysis, highlighting their advantages and disadvantages for human muscle studies, in addition to recent advances in these techniques. These methods can be grouped into three categories based on the initial processing of the tissue: 1) muscle-specific fiber homogenates, 2) cross sections of fiber bundles, and 3) isolated single fibers, with various subtechniques for performing fiber type identification and protein quantification. The relative implementation for each unique methodological approach is analyzed from 83 fiber type-specific studies of proteins in live human muscle found in the literature to date. These studies have investigated several proteins involved in a wide range of cellular functions that are important to muscle tissue. The second half of this review summarizes key findings from this ensemble of fiber type-specific human protein studies. We highlight examples of where this analytical approach has helped to improve understanding of important physiological topics such as insulin sensitivity, muscle hypertrophy, muscle fatigue, and adaptation to different exercise programs.
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Affiliation(s)
- Irene S. Tobias
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
| | - Andrew J. Galpin
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
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Sjöros T, Saunavaara V, Löyttyniemi E, Koivumäki M, Heinonen IHA, Eskelinen J, Virtanen KA, Hannukainen JC, Kalliokoski KK. Intramyocellular lipid accumulation after sprint interval and moderate-intensity continuous training in healthy and diabetic subjects. Physiol Rep 2019; 7:e13980. [PMID: 30740933 PMCID: PMC6369060 DOI: 10.14814/phy2.13980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 12/20/2018] [Accepted: 12/23/2018] [Indexed: 11/24/2022] Open
Abstract
The effects of sprint interval training (SIT) on intramyocellular (IMCL) and extramyocellular (EMCL) lipid accumulation are unclear. We tested the effects of SIT and moderate-intensity continuous training (MICT) on IMCL and EMCL accumulation in a randomized controlled setting in two different study populations; healthy untrained men (n 28) and subjects with type 2 diabetes (T2D) or prediabetes (n 26). Proton magnetic resonance spectroscopy (1 H MRS) was used to determine IMCL and EMCL in the Tibialis anterior muscle (TA) before and after a 2-week exercise period. The exercise period comprised six sessions of SIT or MICT cycling on a cycle ergometer. IMCL increased after SIT compared to MICT (P = 0.042) in both healthy and T2D/prediabetic subjects. On EMCL the training intervention had no significant effect. In conclusion, IMCL serves as an important energy depot during exercise and can be extended by high intensity exercise. The effects of high intensity interval exercise on IMCL seem to be similar regardless of insulin sensitivity or the presence of T2D.
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Affiliation(s)
| | - Virva Saunavaara
- Turku PET CentreTurku University HospitalTurkuFinland
- Department of Medical PhysicsDivision of Medical ImagingTurku University HospitalTurkuFinland
| | | | | | | | | | - Kirsi A. Virtanen
- Turku PET CentreUniversity of TurkuTurkuFinland
- Turku PET CentreTurku University HospitalTurkuFinland
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Loher H, Jenni S, Bucher J, Krüsi M, Kreis R, Boesch C, Christ E. Impaired repletion of intramyocellular lipids in patients with growth hormone deficiency after a bout of aerobic exercise. Growth Horm IGF Res 2018; 42-43:32-39. [PMID: 30153529 DOI: 10.1016/j.ghir.2018.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/04/2018] [Accepted: 08/12/2018] [Indexed: 01/04/2023]
Abstract
BACKGROUND Ectopic lipids such as intramyocellular lipids (IMCL) are depleted by exercise and repleted by diet, whereas intrahepatocellular lipids (IHCL) are increased immediately after exercise. So far, it is unclear how ectopic lipids behave 24 h after exercise and whether the lack of growth hormone (GH) significantly affects ectopic lipids 24 h after exercise. METHODS Seven male patients with growth hormone deficiency (GHD) and seven sedentary male control subjects (CS) were included. VO2max was assessed by spiroergometry; visceral and subcutaneous fat by whole body MRI. 1H-MR-spectroscopy was performed in M. vastus intermedius and in the liver before and after 2 h of exercise at 50% VO2max and 24 h thereafter, while diet and physical activity were standardized. RESULTS Sedentary male subjects (7 GHD, 7 CS) were recruited. Age, BMI, waist circumference, visceral and subcutaneous fat mass was not significantly different between GHD and CS. VO2max was significantly lower in GHD vs. CS. IMCL were diminished through aerobic exercise in both groups: (-11.5 ± 21.9% in CS; -8.9% ±19.1% in GHD) and restored after 24 h in CS (-5.5 ± 26.6% compared to baseline) but not in GHD (-17.9 ± 15.3%). IHCL increased immediately after exercise and decreased to baseline within 24 h. CONCLUSION These findings suggest that GHD may affect repletion of IMCL 24 h after aerobic exercise.
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Affiliation(s)
- Hannah Loher
- Division of Diabetology, Endocrinology, Clinical Nutrition and Metabolism, Inselspital, Bern University Hospital, University of Bern, Switzerland; Department of Medicine, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | - Stefan Jenni
- Division of Diabetology, Endocrinology, Clinical Nutrition and Metabolism, Inselspital, Bern University Hospital, University of Bern, Switzerland; EndoDia Praxis, Biel, Switzerland
| | - Julie Bucher
- Division of Diabetology, Endocrinology, Clinical Nutrition and Metabolism, Inselspital, Bern University Hospital, University of Bern, Switzerland; EndoDia Praxis, Biel, Switzerland
| | - Marion Krüsi
- Division of Diabetology, Endocrinology, Clinical Nutrition and Metabolism, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - Roland Kreis
- Department of Biomedical Research & Institute of Interventional, Diagnostic and Pediatric Radiology, University of Bern, Bern, Switzerland
| | - Chris Boesch
- Department of Biomedical Research & Institute of Interventional, Diagnostic and Pediatric Radiology, University of Bern, Bern, Switzerland
| | - Emanuel Christ
- Division of Diabetology, Endocrinology, Clinical Nutrition and Metabolism, Inselspital, Bern University Hospital, University of Bern, Switzerland; Division of Endocrinology, Diabetology and Metabolism, University Hospital of Basel, Basel, Switzerland.
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7
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Sharma A, Jha AK, Mishra S, Jain A, Chauhan BS, Kathuria M, Rawat KS, Gupta NM, Tripathi R, Mitra K, Sachdev M, Bhatt MLB, Goel A. Imaging and Quantitative Detection of Lipid Droplets by Yellow Fluorescent Probes in Liver Sections of Plasmodium Infected Mice and Third Stage Human Cervical Cancer Tissues. Bioconjug Chem 2018; 29:3606-3613. [DOI: 10.1021/acs.bioconjchem.8b00552] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Ashutosh Sharma
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Ajay K. Jha
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Shachi Mishra
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Ankita Jain
- Endocrinology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Bhavana S. Chauhan
- Parasitology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Manoj Kathuria
- Electron Microscopy Unit, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Kundan S. Rawat
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
- Academy of Scientific
and Innovative Research, Ghaziabad 201 002, India
| | - Neeraj M. Gupta
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Renu Tripathi
- Parasitology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Kalyan Mitra
- Electron Microscopy Unit, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Monika Sachdev
- Endocrinology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Madan L. B. Bhatt
- Department of Radiotherapy, King George’s Medical University, Lucknow 226003, India
| | - Atul Goel
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
- Academy of Scientific
and Innovative Research, Ghaziabad 201 002, India
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Daemen S, van Polanen N, Hesselink MKC. The effect of diet and exercise on lipid droplet dynamics in human muscle tissue. ACTA ACUST UNITED AC 2018. [PMID: 29514886 DOI: 10.1242/jeb.167015] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The majority of fat in the human body is stored as triacylglycerols in white adipose tissue. In the obese state, adipose tissue mass expands and excess lipids are stored in non-adipose tissues, such as skeletal muscle. Lipids are stored in skeletal muscle in the form of small lipid droplets. Although originally viewed as dull organelles that simply store lipids as a consequence of lipid overflow from adipose tissue, lipid droplets are now recognized as key components in the cell that exert a variety of relevant functions in multiple tissues (including muscle). Here, we review the effect of diet and exercise interventions on myocellular lipid droplets and their putative role in insulin sensitivity from a human perspective. We also provide an overview of lipid droplet biology and identify gaps for future research.
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Affiliation(s)
- Sabine Daemen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
| | - Nynke van Polanen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
| | - Matthijs K C Hesselink
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
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9
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The Flexibility of Ectopic Lipids. Int J Mol Sci 2016; 17:ijms17091554. [PMID: 27649157 PMCID: PMC5037826 DOI: 10.3390/ijms17091554] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 02/07/2023] Open
Abstract
In addition to the subcutaneous and the visceral fat tissue, lipids can also be stored in non-adipose tissue such as in hepatocytes (intrahepatocellular lipids; IHCL), skeletal (intramyocellular lipids; IMCL) or cardiac muscle cells (intracardiomyocellular lipids; ICCL). Ectopic lipids are flexible fuel stores that can be depleted by physical exercise and repleted by diet. They are related to obesity and insulin resistance. Quantification of IMCL was initially performed invasively, using muscle biopsies with biochemical and/or histological analysis. 1H-magnetic resonance spectroscopy (1H-MRS) is now a validated method that allows for not only quantifying IMCL non-invasively and repeatedly, but also assessing IHCL and ICCL. This review summarizes the current available knowledge on the flexibility of ectopic lipids. The available evidence suggests a complex interplay between quantitative and qualitative diet, fat availability (fat mass), insulin action, and physical exercise, all important factors that influence the flexibility of ectopic lipids. Furthermore, the time frame of the intervention on these parameters (short-term vs. long-term) appears to be critical. Consequently, standardization of physical activity and diet are critical when assessing ectopic lipids in predefined clinical situations.
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Masschelein E, Van Thienen R, Thomis M, Hespel P. High twin resemblance for sensitivity to hypoxia. Med Sci Sports Exerc 2016; 47:74-81. [PMID: 24870565 DOI: 10.1249/mss.0000000000000386] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Physiological responses to hypoxia vary between individuals, and genetic factors are conceivably involved. Using a monozygotic twin design, we investigated the role of genetic factors in physiological responses to acute hypoxia. METHODS Thirteen pairs of monozygotic twin brothers participated in two experimental sessions in a normobaric hypoxic facility with a 2-wk interval. In one session, fraction of inspired O2 (FiO2) was gradually reduced to 10.7% (approximately 5300 m altitude) over 5 h. During the next 3 h at 10.7%, FiO2 subjects performed a 20-min submaximal exercise bout (EXSUB, 1.2 W·kg) and a maximal incremental exercise test (EXMAX). An identical control experiment was done in normoxia. Cardiorespiratory measurements were continuously performed, and 8-h urine output was collected. RESULTS Compared with normoxia, hypoxia decreased (P < 0.05) arterial O2 saturation (%SpO2) at rest (-22%) and during exercise (-28%). Furthermore, V˙O2max (-39%), HRmax (HR, -8%), maximal pulmonary ventilation (V˙Emax, -11%), and urinary norepinephrine excretion (-31%) were reduced (P < 0.05) whereas HR at rest (25%) and during EXSUB (16%) and V˙E at rest (38%) and during EXSUB (70%) were increased (P < 0.05). However, hypoxia-induced changes (Δ) were not randomly distributed between subjects. Between-pair variance was substantially larger than within-pair variance (P < 0.05) for Δ%SpO2 at rest (approximately threefold) and during exercise (approximately fourfold), ΔV˙O2max (approximately fourfold), ΔHR during exercise (approximately seven- to eightfold), hypoxic ventilatory response (approximately sixfold), and Δ urinary norepinephrine output (approximately threefold). Incidence of acute mountain sickness (AMS) also yielded significant twin similarity (P < 0.05). AMS subjects showed approximately 50% greater drop in urinary norepinephrine and lower hypoxic ventilator response than AMS individuals. CONCLUSIONS Our data suggest that genetic factors regulate cardiorespiratory responses, exercise tolerance, and pathogenesis of AMS symptoms in acute severe hypoxia. Hypoxia-induced sympathetic downregulation was associated with AMS.
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Affiliation(s)
- Evi Masschelein
- 1Exercise Physiology Research Group, Department of Kinesiology, KU Leuven, Leuven, BELGIUM; and 2Physical Activity, Sports and Health Research Group, Department of Kinesiology, KU Leuven, Leuven, BELGIUM
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11
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Ipavec-Levasseur S, Croci I, Choquette S, Byrne NM, Cowin G, O'Moore-Sullivan TM, Prins JB, Hickman IJ. Effect of 1-h moderate-intensity aerobic exercise on intramyocellular lipids in obese men before and after a lifestyle intervention. Appl Physiol Nutr Metab 2015; 40:1262-8. [PMID: 26575100 DOI: 10.1139/apnm-2015-0258] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intramyocellular lipids (IMCL) are depleted in response to an acute bout of exercise in lean endurance-trained individuals; however, it is unclear whether changes in IMCL content are also seen in response to acute and chronic exercise in obese individuals. We used magnetic resonance spectroscopy in 18 obese men and 5 normal-weight controls to assess IMCL content before and after an hour of cycling at the intensity corresponding with each participant's maximal whole-body rate of fat oxidation (Fatmax). Fatmax was determined via indirect calorimetry during a graded exercise test on a cycle ergometer. The same outcome measures were reassessed in the obese group after a 16-week lifestyle intervention comprising dietary calorie restriction and exercise training. At baseline, IMCL content decreased in response to 1 h of cycling at Fatmax in controls (2.8 ± 0.4 to 2.0 ± 0.3 A.U., -39%, p = 0.02), but not in obese (5.4 ± 2.1 vs. 5.2 ± 2.2 A.U., p = 0.42). The lifestyle intervention lead to weight loss (-10.0 ± 5.4 kg, p < 0.001), improvements in maximal aerobic power (+5.2 ± 3.4 mL/(kg·min)), maximal fat oxidation rate (+0.19 ± 0.22 g/min), and a 29% decrease in homeostasis model assessment score (all p < 0.05). However, when the 1 h of cycling at Fatmax was repeated after the lifestyle intervention, there remained no observable change in IMCL (4.6 ± 1.8 vs. 4.6 ± 1.9 A.U., p = 0.92). In summary, there was no IMCL depletion in response to 1 h of cycling at moderate intensity either before or after the lifestyle intervention in obese men. An effective lifestyle intervention including moderate-intensity exercise training did not impact rate of utilisation of IMCL during acute exercise in obese men.
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Affiliation(s)
| | - Ilaria Croci
- a The University of Queensland Diamantina Institute, Brisbane, Australia.,b School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia.,c Mater Research Institute, University of Queensland, Brisbane, Australia
| | - Stéphane Choquette
- d Faculty of Physical Education and Sports, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Nuala M Byrne
- e Bond Institute of Health and Sport, Bond University, Robina, Australia.,f Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - Gary Cowin
- g Centre for Advanced Imaging, University of Queensland, Brisbane, Australia
| | - Trisha M O'Moore-Sullivan
- c Mater Research Institute, University of Queensland, Brisbane, Australia.,h Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Australia
| | - Johannes B Prins
- c Mater Research Institute, University of Queensland, Brisbane, Australia
| | - Ingrid J Hickman
- a The University of Queensland Diamantina Institute, Brisbane, Australia.,c Mater Research Institute, University of Queensland, Brisbane, Australia
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12
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Valaparla SK, Gao F, Daniele G, Abdul-Ghani M, Clarke GD. Fiber orientation measurements by diffusion tensor imaging improve hydrogen-1 magnetic resonance spectroscopy of intramyocellular lipids in human leg muscles. J Med Imaging (Bellingham) 2015; 2:026002. [PMID: 26158115 DOI: 10.1117/1.jmi.2.2.026002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 05/06/2015] [Indexed: 01/15/2023] Open
Abstract
Twelve healthy subjects underwent hydrogen-1 magnetic resonance spectroscopy ([Formula: see text]) acquisition ([Formula: see text]), diffusion tensor imaging (DTI) with a [Formula: see text]-value of [Formula: see text], and fat-water magnetic resonance imaging (MRI) using the Dixon method. Subject-specific muscle fiber orientation, derived from DTI, was used to estimate the lipid proton spectral chemical shift. Pennation angles were measured as 23.78 deg in vastus lateralis (VL), 17.06 deg in soleus (SO), and 8.49 deg in tibialis anterior (TA) resulting in a chemical shift between extramyocellular lipids (EMCL) and intramyocellular lipids (IMCL) of 0.15, 0.17, and 0.19 ppm, respectively. IMCL concentrations were [Formula: see text], [Formula: see text], and [Formula: see text] in SO, VL, and TA, respectively. Significant differences were observed in IMCL and EMCL pairwise comparisons in SO, VL, and TA ([Formula: see text]). Strong correlations were observed between total fat fractions from [Formula: see text] and Dixon MRI for VL ([Formula: see text]), SO ([Formula: see text]), and TA ([Formula: see text]). Bland-Altman analysis between fat fractions (FFMRS and FFMRI) showed good agreement with small limits of agreement (LoA): [Formula: see text] (LoA: [Formula: see text] to 0.69%) in VL, [Formula: see text] (LoA: [Formula: see text] to 1.33%) in SO, and [Formula: see text] (LoA: [Formula: see text] to 0.47%) in TA. The results of this study demonstrate the variation in muscle fiber orientation and lipid concentrations in these three skeletal muscle types.
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Affiliation(s)
- Sunil K Valaparla
- University of Texas Health Science Center , Research Imaging Institute, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3900, United States ; University of Texas Health Science Center , Department of Radiology, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3900, United States
| | - Feng Gao
- University of Texas Health Science Center , Research Imaging Institute, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3900, United States
| | - Giuseppe Daniele
- University of Texas Health Science Center , Department of Medicine, Diabetes Division, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3900, United States ; University of Pisa , Department of Endocrinology, Via Paradisa 2, Pisa 56124, Italy
| | - Muhammad Abdul-Ghani
- University of Texas Health Science Center , Department of Medicine, Diabetes Division, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3900, United States
| | - Geoffrey D Clarke
- University of Texas Health Science Center , Research Imaging Institute, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3900, United States ; University of Texas Health Science Center , Department of Radiology, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3900, United States
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Li Y, Lee S, Langleite T, Norheim F, Pourteymour S, Jensen J, Stadheim HK, Storås TH, Davanger S, Gulseth HL, Birkeland KI, Drevon CA, Holen T. Subsarcolemmal lipid droplet responses to a combined endurance and strength exercise intervention. Physiol Rep 2014; 2:2/11/e12187. [PMID: 25413318 PMCID: PMC4255802 DOI: 10.14814/phy2.12187] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Muscle lipid stores and insulin sensitivity have a recognized association although the mechanism remains unclear. We investigated how a 12‐week supervised combined endurance and strength exercise intervention influenced muscle lipid stores in sedentary overweight dysglycemic subjects and normal weight control subjects (n = 18). Muscle lipid stores were measured by magnetic resonance spectroscopy (MRS), electron microscopy (EM) point counting, and direct EM lipid droplet measurements of subsarcolemmal (SS) and intramyofibrillar (IMF) regions, and indirectly, by deep sequencing and real‐time PCR of mRNA of lipid droplet‐associated proteins. Insulin sensitivity and VO2max increased significantly in both groups after 12 weeks of training. Muscle lipid stores were reduced according to MRS at baseline before and after the intervention, whereas EM point counting showed no change in LD stores post exercise, indicating a reduction in muscle adipocytes. Large‐scale EM quantification of LD parameters of the subsarcolemmal LD population demonstrated reductions in LD density and LD diameters. Lipid droplet volume in the subsarcolemmal LD population was reduced by ~80%, in both groups, while IMF LD volume was unchanged. Interestingly, the lipid droplet diameter (n = 10 958) distribution was skewed, with a lack of small diameter lipid droplets (smaller than ~200 nm), both in the SS and IMF regions. Our results show that the SS LD lipid store was sensitive to training, whereas the dominant IMF LD lipid store was not. Thus, net muscle lipid stores can be an insufficient measure for the effects of training. We have investigated the muscle storage lipids responses to exercise, finding that subsarcolemmal lipid droplets are reduced 80%. Interestingly, we find that the lipid droplet diameter distribution was skewed, with a marked lack of lipid droplets smaller than 200 nm.
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Affiliation(s)
- Yuchuan Li
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | - Sindre Lee
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | - Torgrim Langleite
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway Department of Endocrinology, Morbid Obesity and Preventive Medicine, Faculty of Medicine, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Frode Norheim
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | - Shirin Pourteymour
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | | | | | | | - Svend Davanger
- Department of Anatomy, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | - Hanne L Gulseth
- Department of Endocrinology, Morbid Obesity and Preventive Medicine, Faculty of Medicine, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Kåre I Birkeland
- Department of Endocrinology, Morbid Obesity and Preventive Medicine, Faculty of Medicine, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Christian A Drevon
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | - Torgeir Holen
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
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Brennick MJ, Delikatny J, Pack AI, Pickup S, Shinde S, Zhu JX, Roscoe I, Kim DY, Buxbaum LU, Cater JR, Schwab RJ. Tongue fat infiltration in obese versus lean Zucker rats. Sleep 2014; 37:1095-102, 1102A-1102C. [PMID: 24882904 PMCID: PMC4015383 DOI: 10.5665/sleep.3768] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
STUDY OBJECTIVES Obesity is the most important risk factor for obstructive sleep apnea (OSA), and the effects of obesity may be mediated by tongue fat. Our objective was to examine the effects of obesity on upper airway structures in obese (OBZ) and non-obese (NBZ) Zucker rats. DESIGN Animal study. SETTING Academic Medical Center. PARTICIPANTS OBZ (638.2 ± 39 g; 14.9 ± 1.1 w) and age-matched NBZ Zucker (442.6 ± 37 g, 15.1 ± 1.5 w) rats. INTERVENTIONS TONGUE FAT AND VOLUME AND WERE ASSESSED USING: in vivo magnetic resonance spectroscopy (MRS), magnetic resonance imaging including Dixon imaging for tongue fat volume, ex vivo biochemistry (fat quantification; triglyceride (mg)/tissue (g), and histology (Oil Red O stain). MEASUREMENTS AND RESULTS MRS: overall OBZ tongue fat/water ratio was 2.9 times greater than NBZ (P < 0.002) with the anterior OBZ tongue up to 3.3 times greater than NBZ (P < 0.002). Biochemistry: Triglyceride (TG) in the tongue was 4.4 times greater in OBZ versus NBZ (P < 0.0006). TG was greater in OBZ tongue (3.57 ± 1.7 mg/g) than OBZ masseter muscle (0.28 ± 0.1; P < 0.0001) but tongue and masseter TG were not different in NBZ rats (0.82 ± 0.3 versus 0.28 ± 0.1 mg/g, P = 0.67). Dixon fat volume was significantly increased in OBZ (56 ± 15 mm3) versus NBZ (34 ± 5 mm3, P < 0.004). Histology demonstrated a greater degree of intracellular muscle fat and extramuscular fat infiltration in OBZ versus NBZ rats. CONCLUSIONS Genetically obese rats had a large degree of fat infiltration in the tongue compared to both skeletal muscle and tongue tissues of the non-obese age-matched littermates. The significant fat increase and sequestration in the obese tongue may play a role in altered tongue neuromuscular function, tongue stiffness or metabolic function.
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Affiliation(s)
| | | | - Allan I. Pack
- Center for Sleep and Circadian Neurobiology
- Division of Sleep Medicine
| | | | | | | | | | | | - Laurence U. Buxbaum
- Philadephia Research and Education Foundation, Philadelphia, PA
- Division of Infectious Disease, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | | | - Richard J. Schwab
- Center for Sleep and Circadian Neurobiology
- Division of Sleep Medicine
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15
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Mehlem A, Hagberg CE, Muhl L, Eriksson U, Falkevall A. Imaging of neutral lipids by oil red O for analyzing the metabolic status in health and disease. Nat Protoc 2013; 8:1149-54. [PMID: 23702831 DOI: 10.1038/nprot.2013.055] [Citation(s) in RCA: 543] [Impact Index Per Article: 49.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Excess lipid accumulation in peripheral tissues is a key feature of many metabolic diseases. Therefore, techniques for imaging and quantifying lipids in various tissues are important for understanding and evaluating the overall metabolic status of a research subject. Here we present a protocol that detects neutral lipids and lipid droplet (LD) morphology by oil red O (ORO) staining of sections from frozen tissues. The method allows for easy estimation of tissue lipid content and distribution using only basic laboratory and computer equipment. Furthermore, the procedure described here is well suited for the comparison of different metabolically challenged animal models. As an example, we include data on muscular and hepatic lipid accumulation in diet-induced and genetically induced diabetic mice. The experimental description presents details for optimal staining of lipids using ORO, including tissue collection, sectioning, staining, imaging and measurements of tissue lipids, in a time frame of less than 2 d.
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Affiliation(s)
- Annika Mehlem
- Tissue Biology Group, Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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16
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Sousa M, Simões HG, Castro CCD, Otaduy MCG, Negrão CE, Pereira RMR, Madsen K, Silva MERD. Carbohydrate supplementation increases intramyocellular lipid stores in elite runners. Metabolism 2012; 61:1189-96. [PMID: 22421463 DOI: 10.1016/j.metabol.2012.01.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Revised: 01/06/2012] [Accepted: 01/17/2012] [Indexed: 10/28/2022]
Abstract
The objective was to determine the effects of carbohydrate (CHO) supplementation on exercise-induced hormone responses and post-training intramyocellular lipid stores (IMCL). Twenty-four elite male athletes (28.0±1.2 years) were randomized to receive CHO (maltodextrin solution) or zero energy placebo solution (control group). The high-intensity running protocol consisted of 10×800 m at 100% of the best 3000-m speed (Vm3 km) and 2×1000 m maximal bouts in the morning and a submaximal 10-km continuous easy running in the afternoon of day 9. IMCL concentrations were assessed by (1)H-MRS before (-day 9) and after training (day 9) in soleus (SO) and tibialis anterior (TA) muscles. Blood hormones were also measured before, during, and post-exercise. The percent change (Δ%) in TA-IMCL was higher in the CHO group (47.9±24.5 IMCL/Cr) than in the control group (-1.7±13.1, respectively) (P=.04). Insulin concentrations were higher in the CHO group post-intermittent running compared to control (P=.02). Circulating levels of free fatty acids and GH were lower in the CHO group (P>.01). The decline in performance in the 2nd 1000-m bout was also attenuated in this group compared to control (P<.001 and P=.0035, respectively). The hormonal milieu (higher insulin and lower GH levels) in the CHO group, together with unchanged free fatty acid levels, probably contributed to the increased IMCL stores. This greater energy storage capacity may have improved post-exercise recovery and thus prevented performance deterioration.
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Affiliation(s)
- Maysa Sousa
- Laboratory of Medical Investigation LIM-18, Faculty of Medicine, University of São Paulo, Av. Dr. Arnaldo 455, São Paulo, SP, Brazil.
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17
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Zhu H, Liu C, Sun J, Li M, Hua J. Effect of GSK-3 inhibitor on the proliferation of multipotent male germ line stem cells (mGSCs) derived from goat testis. Theriogenology 2012; 77:1939-50. [DOI: 10.1016/j.theriogenology.2012.01.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 01/19/2012] [Accepted: 01/19/2012] [Indexed: 01/02/2023]
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18
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Vincent B, Windelinckx A, Van Proeyen K, Masschelein E, Nielens H, Ramaekers M, Van Leemputte M, Hespel P, Thomis M. Alpha-actinin-3 deficiency does not significantly alter oxidative enzyme activity in fast human muscle fibres. Acta Physiol (Oxf) 2012; 204:555-61. [PMID: 21933355 DOI: 10.1111/j.1748-1716.2011.02366.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
AIM In Western European populations, about 18% of all individuals have a complete deficiency of the alpha-actinin-3 protein owing to homozygosity for a stop codon mutation (R577X) in the ACTN3 gene. Actn3(-/-) knock-out mice show increased activity of multiple enzymes in the aerobic metabolic pathway in fast muscle fibres. Whether this observation is also present in human XX genotype carriers compared to RR carriers has not been studied in a fibre-type-specific approach in humans. The purpose of this study was therefore to compare fibre-type-specific oxidative enzyme activity in humans with a different ACTN3 R577X genotype. METHODS Vastus lateralis muscle biopsy samples of 17 XX and 16 RR subjects were used to measure markers of oxidative capacity [cytochrome c oxidase (CYTOX) and succinate dehydrogenase (SDH)] in a fibre-type-specific assay using enzyme histochemistry. RESULTS Cytochrome c oxidase staining showed no significant genotype group differences in type I or type II muscle fibres. Also, we found no significant differences in SDH staining of fast fibres comparing XX and RR carriers. CONCLUSION In conclusion, the increase in oxidative enzyme activity of fast muscle fibres, as reported in an Actn3(-/-) knock-out mouse, was not observed in our human samples. Known differences in metabolic characteristics of muscle fibres in rodents compared to humans may in part explain this discrepancy in findings.
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Affiliation(s)
- B Vincent
- Research Centre for Exercise and Health, Department of Biomedical Kinesiology, Faculty of Kinesiology and Rehabilitation Sciences, K. U. Leuven, Belgium
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19
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Use of BODIPY (493/503) to visualize intramuscular lipid droplets in skeletal muscle. J Biomed Biotechnol 2011; 2011:598358. [PMID: 21960738 PMCID: PMC3180081 DOI: 10.1155/2011/598358] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Revised: 07/21/2011] [Accepted: 08/02/2011] [Indexed: 11/22/2022] Open
Abstract
Triglyceride storage is altered across various chronic health conditions necessitating various techniques to visualize and quantify lipid droplets (LDs). Here, we describe the utilization of the BODIPY (493/503) dye in skeletal muscle as a means to analyze LDs. We found that the dye was a convenient and simple approach to visualize LDs in both sectioned skeletal muscle and cultured adult single fibers. Furthermore, the dye was effective in both fixed and nonfixed cells, and the staining seemed unaffected by permeabilization. We believe that the use of the BODIPY (493/503) dye is an acceptable alternative and, under certain conditions, a simpler method for visualizing LDs stored within skeletal muscle.
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20
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A new method for non-invasive estimation of human muscle fiber type composition. PLoS One 2011; 6:e21956. [PMID: 21760934 PMCID: PMC3131401 DOI: 10.1371/journal.pone.0021956] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Accepted: 06/14/2011] [Indexed: 01/30/2023] Open
Abstract
Background It has been established that excellence in sports with short and long exercise duration requires a high proportion of fast-twitch (FT) or type-II fibers and slow-twitch (ST) or type-I fibers, respectively. Until today, the muscle biopsy method is still accepted as gold standard to measure muscle fiber type composition. Because of its invasive nature and high sampling variance, it would be useful to develop a non-invasive alternative. Methodology Eighty-three control subjects, 15 talented young track-and-field athletes, 51 elite athletes and 14 ex-athletes volunteered to participate in the current study. The carnosine content of all 163 subjects was measured in the gastrocnemius muscle by proton magnetic resonance spectroscopy (1H-MRS). Muscle biopsies for fiber typing were taken from 12 untrained males. Principal Findings A significant positive correlation was found between muscle carnosine, measured by 1H-MRS, and percentage area occupied by type II fibers. Explosive athletes had ∼30% higher carnosine levels compared to a reference population, whereas it was ∼20% lower than normal in typical endurance athletes. Similar results were found in young talents and ex-athletes. When active elite runners were ranked according to their best running distance, a negative sigmoidal curve was found between logarithm of running distance and muscle carnosine. Conclusions Muscle carnosine content shows a good reflection of the disciplines of elite track-and-field athletes and is able to distinguish between individual track running distances. The differences between endurance and sprint muscle types is also observed in young talents and former athletes, suggesting this characteristic is genetically determined and can be applied in early talent identification. This quick method provides a valid alternative for the muscle biopsy method. In addition, this technique may also contribute to the diagnosis and monitoring of many conditions and diseases that are characterized by an altered muscle fiber type composition.
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Ingram KH, Lara-Castro C, Gower BA, Makowsky R, Allison DB, Newcomer BR, Munoz AJ, Beasley TM, Lawrence JC, Lopez-Ben R, Rigsby DY, Garvey WT. Intramyocellular lipid and insulin resistance: differential relationships in European and African Americans. Obesity (Silver Spring) 2011; 19:1469-75. [PMID: 21436797 PMCID: PMC3171736 DOI: 10.1038/oby.2011.45] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Insulin resistance has been associated with the accumulation of fat within skeletal muscle fibers as intramyocellular lipid (IMCL). Here, we have examined in a cross-sectional study the interrelationships among IMCL, insulin sensitivity, and adiposity in European Americans (EAs) and African Americans (AAs). In 43 EA and 43 AA subjects, we measured soleus IMCL content with proton-magnetic resonance spectroscopy, insulin sensitivity with hyperinsulinemic-euglycemic clamp, and body composition with dual-energy X-ray absorptiometry. The AA and EA subgroups had similar IMCL content, insulin sensitivity, and percent fat, but only in EA was IMCL correlated with insulin sensitivity (r = -0.47, P < 0.01), BMI (r = 0.56, P < 0.01), percent fat (r = 0.35, P < 0.05), trunk fat (r = 0.47, P < 0.01), leg fat (r = 0.40, P < 0.05), and waist and hip circumferences (r = 0.54 and 0.55, respectively, P < 0.01). In a multiple regression model including IMCL, race, and a race by IMCL interaction, the interaction was found to be a significant predictor (t = 1.69, DF = 1, P = 0.0422). IMCL is related to insulin sensitivity and adiposity in EA but not in AA, suggesting that IMCL may not function as a pathophysiological factor in individuals of African descent. These results highlight ethnic differences in the determinants of insulin sensitivity and in the pathogenesis of the metabolic syndrome trait cluster.
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Affiliation(s)
- Katherine H Ingram
- Department of Biostatistics, University of Alabama, Birmingham, Alabama, USA.
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22
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Van Proeyen K, Szlufcik K, Nielens H, Deldicque L, Van Dyck R, Ramaekers M, Hespel P. High-fat diet overrules the effects of training on fiber-specific intramyocellular lipid utilization during exercise. J Appl Physiol (1985) 2011; 111:108-16. [PMID: 21551007 DOI: 10.1152/japplphysiol.01459.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this study, we compared the effects of endurance training in the fasted state (F) vs. the fed state [ample carbohydrate intake (CHO)] on exercise-induced intramyocellular lipid (IMCL) and glycogen utilization during a 6-wk period of a hypercaloric (∼+30% kcal/day) fat-rich diet (HFD; 50% of kcal). Healthy male volunteers (18-25 yrs) received a HFD in conjunction with endurance training (four times, 60-90 min/wk) either in F (n = 10) or with CHO before and during exercise sessions (n = 10). The control group (n = 7) received a HFD without training and increased body weight by ∼3 kg (P < 0.001). Before and after a HFD, the subjects performed a 2-h constant-load bicycle exercise test in F at ∼70% maximal oxygen uptake rate. A HFD, both in the absence (F) or presence (CHO) of training, elevated basal IMCL content by ∼50% in type I and by ∼75% in type IIa fibers (P < 0.05). Independent of training in F or CHO, a HFD, as such, stimulated exercise-induced net IMCL breakdown by approximately twofold in type I and by approximately fourfold in type IIa fibers. Furthermore, exercise-induced net muscle glycogen breakdown was not significantly affected by a HFD. It is concluded that a HFD stimulates net IMCL degradation by increasing basal IMCL content during exercise in type I and especially IIa fibers. Furthermore, a hypercaloric HFD provides adequate amounts of carbohydrates to maintain high muscle glycogen content during training and does not impair exercise-induced muscle glycogen breakdown.
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Affiliation(s)
- Karen Van Proeyen
- Research Centre for Exercise and Health, Department of Biomedical Kinesiology, Katholieke Universiteit Leuven, Leuven, Belgium
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Van Proeyen K, De Bock K, Hespel P. Training in the fasted state facilitates re-activation of eEF2 activity during recovery from endurance exercise. Eur J Appl Physiol 2010; 111:1297-305. [DOI: 10.1007/s00421-010-1753-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2010] [Indexed: 10/18/2022]
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Shaw CS, Clark J, Wagenmakers AJM. The effect of exercise and nutrition on intramuscular fat metabolism and insulin sensitivity. Annu Rev Nutr 2010; 30:13-34. [PMID: 20373917 DOI: 10.1146/annurev.nutr.012809.104817] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Intramuscular triacylglycerol (IMTG) is both a dynamic fat-storage depot that can expand during periods of elevated lipid availability and a fatty acid source that can be utilized during periods of increased energy expenditure in active individuals. Although many studies have investigated the lifestyle determinants of IMTG content, the results are far from consistent, and studies attempting to unravel the mechanisms behind IMTG metabolism are in their infancy. The limited evidence available suggests that the enzymes responsible for skeletal muscle lipolysis and IMTG synthesis play an important role in determining the fate of fatty acids and therefore the concentration of lipid metabolites and insulin sensitivity of skeletal muscle. This review provides a summary of current knowledge on the effects of acute and chronic exercise as well as energy intake and macronutrient composition of the diet upon the metabolism of IMTG and the implications for metabolic health.
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Affiliation(s)
- Christopher S Shaw
- School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT United Kingdom.
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Nadeau KJ, Zeitler PS, Bauer TA, Brown MS, Dorosz JL, Draznin B, Reusch JEB, Regensteiner JG. Insulin resistance in adolescents with type 2 diabetes is associated with impaired exercise capacity. J Clin Endocrinol Metab 2009; 94:3687-95. [PMID: 19584191 PMCID: PMC2758737 DOI: 10.1210/jc.2008-2844] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT The incidence of pediatric type 2 diabetes (T2D) is rising, with unclear effects on the cardiovascular system. Cardiopulmonary fitness, a marker of morbidity and mortality, is abnormal in adults with T2D, yet the mechanisms are incompletely understood. OBJECTIVE We hypothesized that cardiopulmonary fitness would be reduced in youth with T2D in association with insulin resistance (IR) and cardiovascular dysfunction. DESIGN, SETTING, AND PARTICIPANTS We conducted a cross-sectional study at an academic hospital that included 14 adolescents (age range, 12-19 yr) with T2D, 13 equally obese adolescents and 12 lean adolescents similar in age, pubertal stage, and activity level. MAIN OUTCOME MEASURES Cardiopulmonary fitness was measured by peak oxygen consumption (VO(2)peak) and oxygen uptake kinetics (VO(2)kinetics), IR by hyperinsulinemic clamp, cardiac function by echocardiography, vascular function by venous occlusion plethysmography, body composition by dual-energy x-ray absorptiometry, intramyocellular lipid by magnetic resonance spectroscopy, and inflammation by serum markers. RESULTS Adolescents with T2D had significantly decreased VO(2)peak and insulin sensitivity, and increased soleus intramyocellular lipid, C-reactive protein, and IL-6 compared to obese or lean adolescents. Adolescents with T2D also had significantly prolonged VO(2)kinetics, decreased work rate, vascular reactivity, and adiponectin, and increased left ventricular mass and fatty acids compared to lean adolescents. In multivariate linear regression analysis, IR primarily, and fasting free fatty acids and forearm blood flow secondarily, were significant independent predictors of VO(2)peak. CONCLUSIONS Given the strong relationship between decreased cardiopulmonary fitness and increased mortality, these findings in children are especially concerning and represent early signs of impaired cardiac function.
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Affiliation(s)
- Kristen J Nadeau
- Division of Pediatric Endocrinology, The Children's Hospital, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA.
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Devries MC, Lowther SA, Glover AW, Hamadeh MJ, Tarnopolsky MA. IMCL area density, but not IMCL utilization, is higher in women during moderate-intensity endurance exercise, compared with men. Am J Physiol Regul Integr Comp Physiol 2007; 293:R2336-42. [PMID: 17913867 DOI: 10.1152/ajpregu.00510.2007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Women use more fat during endurance exercise as evidenced by a lower respiratory exchange ratio (RER). The contribution of intramyocellular lipid (IMCL) to lipid oxidation during endurance exercise is controversial, and studies investigating sex differences in IMCL utilization have found conflicting results. We determined the effect of sex on net IMCL use during an endurance exercise bout using an ultrastructural evaluation. Men ( n = 17) and women ( n = 19) completed 90-min cycling at 63% V̇o2peak. Biopsies were taken before and after exercise and fixed for electron microscopy to determine IMCL size, # IMCL/area, IMCL area density, and the % IMCL touching mitochondria. Women had a lower RER and carbohydrate oxidation rate and a higher lipid oxidation rate during exercise ( P < 0.05), compared with men. Women had a higher # IMCL/area and IMCL area density ( P < 0.05), compared with men. Women, but not men, had a higher % IMCL touching mitochondria postexercise ( P = 0.03). Exercise decreased IMCL area density ( P = 0.01), due to a decrease in the # IMCL/area ( P = 0.02). There was no sex difference in IMCL size or net use. In conclusion, women have higher IMCL area density compared with men, due to an increased # IMCL and not an increased IMCL size, as well as an increased % IMCL touching mitochondria postexercise. Endurance exercise resulted in a net decrease in IMCL density due to decreased number of IMCL, not decreased IMCL size, in both sexes.
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Affiliation(s)
- Michaela C Devries
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
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Shaw CS, Jones DA, Wagenmakers AJM. Network distribution of mitochondria and lipid droplets in human muscle fibres. Histochem Cell Biol 2007; 129:65-72. [PMID: 17938948 DOI: 10.1007/s00418-007-0349-8] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2007] [Indexed: 12/22/2022]
Abstract
The objective of the present study was to develop a combination of fluorescent stains that would allow visualisation of the network of mitochondria and lipid droplets (intramyocellular lipids or IMCL) in human skeletal muscle fibres by means of conventional and confocal microscopy. Muscle biopsies were taken from the vastus lateralis of three lean, healthy and physically active male subjects. Frozen muscle sections were stained for mitochondria using antibodies against three mitochondrial proteins; porin, cytochrome c oxidase (COX) and NADH-ubiquinol oxidoreductase and neutral lipids were stained with oil red O. Anti-COX staining produced images with the strongest fluorescence signal and the highest resolution of the mitochondrial network and this stain was successfully combined with the antibody against type I fibre myosin. A highly organised matrix arrangement of mitochondria within the sarcomeres (in pairs at the I-band) was observed in the oxidative type I fibres. The density of mitochondria was the highest in the subsarcolemmal region. Anti-COX staining was combined with oil red O demonstrating that in type I fibres lipid droplets are mainly located in the space between the mitochondria.
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Affiliation(s)
- Christopher S Shaw
- Exercise Metabolism Research Group, School of Sport and Exercise Sciences, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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