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Bajpeyi S, Apaflo JN, Rosas V, Sepulveda-Rivera K, Varela-Ramirez A, Covington JD, Galgani JE, Ravussin E. Effect of an acute long-duration exercise bout on skeletal muscle lipid droplet morphology, GLUT 4 protein, and perilipin protein expression. Eur J Appl Physiol 2023; 123:2771-2778. [PMID: 37368137 DOI: 10.1007/s00421-023-05266-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 06/21/2023] [Indexed: 06/28/2023]
Abstract
PURPOSE Smaller lipid droplet morphology and GLUT 4 protein expression have been associated with greater muscle oxidative capacity and glucose uptake, respectively. The main purpose of this study was to determine the effect of an acute long-duration exercise bout on skeletal muscle lipid droplet morphology, GLUT4, perilipin 3, and perilipin 5 expressions. METHODS Twenty healthy men (age 24.0 ± 1.0 years, BMI 23.6 ± 0.4 kg/m2) were recruited for the study. The participants were subjected to an acute bout of exercise on a cycle ergometer at 50% VO2max until they reached a total energy expenditure of 650 kcal. The study was conducted after an overnight fast. Vastus lateralis muscle biopsies were obtained before and immediately after exercise for immunohistochemical analysis to determine lipid, perilipin 3, perilipin 5, and GLUT4 protein contents while GLUT 4 mRNA was quantified using RT-qPCR. RESULTS Lipid droplet size decreased whereas total intramyocellular lipid content tended to reduce (p = 0.07) after an acute bout of endurance exercise. The density of smaller lipid droplets in the peripheral sarcoplasmic region significantly increased (0.584 ± 0.04 to 0.638 ± 0.08 AU; p = 0.01) while larger lipid droplets significantly decreased (p < 0.05). GLUT4 mRNA tended to increase (p = 0.05). There were no significant changes in GLUT 4, perilipin 3, and perilipin 5 protein levels. CONCLUSION The study demonstrates that exercise may impact metabolism by enhancing the quantity of smaller lipid droplets over larger lipid droplets.
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Affiliation(s)
- Sudip Bajpeyi
- Metabolic, Nutrition, and Exercise Research (MiNER) Laboratory, Department of Kinesiology, The University of Texas at El Paso, 500 University Ave, El Paso, TX, 79968, USA.
| | - Jehu N Apaflo
- Metabolic, Nutrition, and Exercise Research (MiNER) Laboratory, Department of Kinesiology, The University of Texas at El Paso, 500 University Ave, El Paso, TX, 79968, USA
| | - Victoria Rosas
- Metabolic, Nutrition, and Exercise Research (MiNER) Laboratory, Department of Kinesiology, The University of Texas at El Paso, 500 University Ave, El Paso, TX, 79968, USA
| | - Keisha Sepulveda-Rivera
- Metabolic, Nutrition, and Exercise Research (MiNER) Laboratory, Department of Kinesiology, The University of Texas at El Paso, 500 University Ave, El Paso, TX, 79968, USA
| | - Armando Varela-Ramirez
- The Cellular Characterization and Biorepository (CCB) Core Facility, Border Biomedical Research Center, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX, USA
| | - Jeffrey D Covington
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jose E Galgani
- Faculty of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Eric Ravussin
- Laboratory of Skeletal Muscle Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
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Covington JD, Zong Y, Talat A, Strock C, Tomaszewicz K, Zivny J, Yang MX. Mass-Forming Gastric Heterotopia of the Rectum: A Series of 3 Cases from a Single Tertiary Health Center. Am J Case Rep 2022; 23:e936631. [PMID: 35881563 PMCID: PMC9339256 DOI: 10.12659/ajcr.936631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Case series
Patient: Male, 25-year-old • Female, 58-year-old • Male, 33-year-old
Final Diagnosis: Rectal gastric heterotopia
Symptoms: Anal pain • hematochezia
Medication: —
Clinical Procedure: Endoscopic mucosal resection
Specialty: Gastroenterology and Hepatology
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Affiliation(s)
- Jeffrey D. Covington
- Department of Pathology, University of Massachusetts Medical School, Worcester, USA, MA
| | - Yang Zong
- Department of Pathology, University of Massachusetts Medical School, Worcester, USA, MA
| | - Arslan Talat
- Department of Gastroenterology, University of Massachusetts Medical School, Worcester, USA, MA
| | - Cara Strock
- Department of Pathology, University of Massachusetts Medical School, Worcester, USA, MA
| | - Keith Tomaszewicz
- Department of Pathology, University of Massachusetts Medical School, Worcester, USA, MA
| | - Jaroslav Zivny
- Department of Gastroenterology, University of Massachusetts Medical School, Worcester, USA, MA
| | - Michelle X. Yang
- Department of Pathology, University of Massachusetts Medical School, Worcester, USA, MA
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3
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Galvan MJ, Sanchez MJ, McAinch AJ, Covington JD, Boyle JB, Bajpeyi S. Four weeks of electrical stimulation improves glucose tolerance in a sedentary overweight or obese Hispanic population. Endocr Connect 2022; 11:e210533. [PMID: 35007207 PMCID: PMC8859936 DOI: 10.1530/ec-21-0533] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 01/10/2022] [Indexed: 11/08/2022]
Abstract
INTRODUCTION/PURPOSE Most US adults (54%) do not meet the minimum exercise recommendations by the American College of Sports Medicine. Neuromuscular electrical stimulation (NMES) is a novel alternate strategy to induce muscle contraction. However, the effectiveness of NMES to improve insulin sensitivity and energy expenditure is unclear. The purpose of this study was to investigate the effects of 4 weeks of NMES on glucose tolerance in a sedentary overweight or obese population. METHODS Participants (n = 10; age: 36.8 ± 3.8 years; BMI = 32 ± 1.3 kg/m2) were randomized into either control or NMES group. All participants received bilateral quadriceps stimulation (12 sessions; 30 min/session; three times/week at 50 Hz and 300 µs pulse width) altering pulse amplitude to either provide low-intensity sensory level (control; tingling sensation) or at high-intensity neuromuscular level (NMES; maximum tolerable levels with visible muscle contraction). Glucose tolerance was assessed by a 3-h oral glucose tolerance test (OGTT), and substrate utilization was measured by indirect calorimetry and body composition via dual X-ray absorptiometry at baseline and after 4 weeks of NMES intervention. RESULTS Control and NMES groups had comparable fasting blood glucose, glucose tolerance, substrate utilization, and muscle mass at baseline. Four weeks of NMES resulted in a significant improvement in glucose tolerance measured by OGTT, whereas no change was observed in the control group. There was no change in substrate utilization and muscle mass in both control and NMES groups. CONCLUSION NMES is a novel and effective strategy to improve glucose tolerance in an at-risk overweight or obese sedentary population.
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Affiliation(s)
- Michelle J Galvan
- Metabolic, Nutrition, and Exercise Research (MiNER) Laboratory, Department of Kinesiology, University of Texas at El Paso, El Paso, Texas, USA
| | - Michael J Sanchez
- Metabolic, Nutrition, and Exercise Research (MiNER) Laboratory, Department of Kinesiology, University of Texas at El Paso, El Paso, Texas, USA
| | - Andrew J McAinch
- Institute for Health and Sport (IHES), Victoria University, Melbourne, Victoria, Australia
- Australian Institute for Musculoskeletal Science (AIMSS), Victoria University, Melbourne, Victoria, Australia
| | - Jeffrey D Covington
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Jason B Boyle
- Metabolic, Nutrition, and Exercise Research (MiNER) Laboratory, Department of Kinesiology, University of Texas at El Paso, El Paso, Texas, USA
| | - Sudip Bajpeyi
- Metabolic, Nutrition, and Exercise Research (MiNER) Laboratory, Department of Kinesiology, University of Texas at El Paso, El Paso, Texas, USA
- Correspondence should be addressed to S Bajpeyi:
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Wilcock JN, Covington JD, Akselrod D, Iuga A, Cassone E, Zenali M. Giant polypoid masses on endoscopy with a surprising nature: dedifferentiated liposarcoma. Gastrointest Endosc 2020; 91:1400-1401. [PMID: 31923408 DOI: 10.1016/j.gie.2020.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 01/02/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Jonathan N Wilcock
- Department of Pathology, The University of Vermont Medical Center, Burlington, Vermont, USA
| | - Jeffrey D Covington
- Department of Pathology, The University of Vermont Medical Center, Burlington, Vermont, USA
| | - Dmitriy Akselrod
- Department of Radiology, The University of Vermont Medical Center, Burlington, Vermont, USA
| | - Alina Iuga
- Department of Pathology, Columbia University Irving Medical Center, New York, New York, USA
| | - Eugene Cassone
- Department of Gastroenterology, The University of Vermont Health Network-Champlain Valley Physicians Hospital, Plattsburgh, New York, USA
| | - Maryam Zenali
- Department of Pathology, The University of Vermont Medical Center, Burlington, Vermont, USA
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Amador M, Meza CA, McAinch AJ, King GA, Covington JD, Bajpeyi S. Exercise-Induced Improvements in Insulin Sensitivity Are Not Attenuated by a Family History of Type 2 Diabetes. Front Endocrinol (Lausanne) 2020; 11:120. [PMID: 32231642 PMCID: PMC7088124 DOI: 10.3389/fendo.2020.00120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 02/24/2020] [Indexed: 01/15/2023] Open
Abstract
Introduction: A family history of type 2 diabetes (FH+) is a major risk factor for the development of insulin resistance and type 2 diabetes. However, it remains unknown whether exercise-induced improvements in insulin sensitivity and metabolic flexibility are impacted by a FH+. Therefore, we investigated whether improvements in insulin sensitivity, metabolic flexibility, body composition, aerobic fitness and muscle strength are limited by a FH+ following eight weeks of combined exercise training compared to individuals without a family history of type 2 diabetes (FH-). Methods: Twenty (n = 10 FH-, n = 10 FH+) young, healthy, sedentary, normoglycemic, Mexican-American males (age: FH- 22.50 ± 0.81, FH+ 23.41 ± 0.86 years; BMI: FH- 27.91 ± 1.55, FH+ 26.64 ± 1.02 kg/m2) underwent eight weeks of combined aerobic and resistance exercise training three times/week (35 min aerobic followed by six full-body resistance exercises). Insulin sensitivity was assessed via hyperinsulinemic euglycemic clamps. Metabolic flexibility was assessed by the change in respiratory quotient from fasted to insulin-stimulated states. Body composition was determined using dual-energy x-ray absorptiometry. Aerobic fitness was determined by a graded exercise test, and upper- and lower-body strength were assessed via one-repetition maximum bench press and leg strength dynamometer, respectively. Results: Insulin sensitivity, metabolic flexibility, aerobic fitness and strength were not different between groups (p > 0.05). Eight weeks of combined aerobic and resistance exercise training improved insulin sensitivity (FH- p = 0.02, FH+ p = 0.002), increased fat free mass (FH- p = 0.006, FH+ p = 0.001), aerobic fitness (FH- p = 0.03, FH+ p = 0.002), and upper- (FH- p = 0.0001, FH+ p = 0.0001) and lower-body strength (FH- p = 0.0009, FH+ p = 0.0003), but did not change metabolic flexibility (p > 0.05) in both groups. Exercise-induced improvements in metabolic outcomes were similar between groups. Conclusions: Insulin sensitivity, metabolic flexibility, aerobic fitness and strength were not compromised by a FH+. Additionally, a FH+ is not a limiting factor for exercise-induced improvements in insulin sensitivity, aerobic fitness, body composition, and strength in normoglycemic young Mexican-American men.
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Affiliation(s)
- Manuel Amador
- Metabolic, Nutrition and Exercise Research (MiNER) Laboratory, Department of Kinesiology, University of Texas at El Paso, El Paso, TX, United States
| | - Cesar A. Meza
- Metabolic, Nutrition and Exercise Research (MiNER) Laboratory, Department of Kinesiology, University of Texas at El Paso, El Paso, TX, United States
| | - Andrew J. McAinch
- Institute for Health and Sport, College of Health and Biomedicine, Victoria University, Melbourne, VIC, Australia
- Australian Institute for Musculoskeletal Science, Victoria University, Melbourne, VIC, Australia
| | - George A. King
- Metabolic, Nutrition and Exercise Research (MiNER) Laboratory, Department of Kinesiology, University of Texas at El Paso, El Paso, TX, United States
| | - Jeffrey D. Covington
- Department of Pathology and Laboratory Medicine, University of Vermont, Burlington, VT, United States
| | - Sudip Bajpeyi
- Metabolic, Nutrition and Exercise Research (MiNER) Laboratory, Department of Kinesiology, University of Texas at El Paso, El Paso, TX, United States
- *Correspondence: Sudip Bajpeyi
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6
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Rankins C, Covington JD, Devitt K, Kalof A, Goetz R, Gardner JA. Novel Cytogenetic Characterization of Pleomorphic Hyalinizing Angiectatic Tumor (PHAT). J Assoc Genet Technol 2019; 45:116-120. [PMID: 31554742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 09/27/2019] [Indexed: 06/10/2023]
Abstract
Pleomorphic hyalinizing angiectatic tumor (PHAT) is a rare soft tissue tumor that, despite its characteristic marked pleomorphism, is slow growing and of intermediate grade malignancy. PHAT is not known to metastasize, but is locally aggressive with a post-excision recurrence rate of up to 50%. Two other soft tissue tumors, hemosiderotic fibrolipomatous tumor (HFLT) and myxoinflammatory fibroblastic sarcoma (MIFS), share some morphological features with PHAT, and all three have been found to possess a t(1;10) translocation. Thus, it has been suggested PHAT, HFLT, and MIFS exist within a spectrum of a single entity; however, there is only one case of PHAT with a full cytogenetic profile and this showed the t(1;10). We report a case of PHAT with a complete cytogenetic profile differing from the previously reported case. Our case demonstrates 47,XY,+7,der(7)(qter::?::q31::?::pter::?::cen::?::pter::?::q31::?::qter)x2[20]/46,XY[10] karyotype with the typical morphologic features and immunohistochemical staining pattern seen in PHAT. This suggests that PHAT may be a distinctly separate entity and not within the spectrum of HFLT and MIFS.
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Affiliation(s)
- Casey Rankins
- Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington, VT
| | - Jeffrey D Covington
- Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington, VT
| | - Katherine Devitt
- Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington, VT
| | - Alexandra Kalof
- Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington, VT
| | - Rebecca Goetz
- Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington, VT
| | - Juli-Anne Gardner
- Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington, VT
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7
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Toledo FGS, Johannsen DL, Covington JD, Bajpeyi S, Goodpaster B, Conley KE, Ravussin E. Impact of prolonged overfeeding on skeletal muscle mitochondria in healthy individuals. Diabetologia 2018; 61:466-475. [PMID: 29150696 PMCID: PMC5770194 DOI: 10.1007/s00125-017-4496-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 10/17/2017] [Indexed: 12/01/2022]
Abstract
AIMS/HYPOTHESES Reduced mitochondrial capacity in skeletal muscle has been observed in obesity and type 2 diabetes. In humans, the aetiology of this abnormality is not well understood but the possibility that it is secondary to the stress of nutrient overload has been suggested. To test this hypothesis, we examined whether sustained overfeeding decreases skeletal muscle mitochondrial content or impairs function. METHODS Twenty-six healthy volunteers (21 men, 5 women, age 25.3 ± 4.5 years, BMI 25.5 ± 2.4 kg/m2) underwent a supervised protocol consisting of 8 weeks of high-fat overfeeding (40% over baseline energy requirements). Before and after overfeeding, we measured systemic fuel oxidation by indirect calorimetry and performed skeletal muscle biopsies to measure mitochondrial gene expression, content and function in vitro. Mitochondrial function in vivo was measured by 31P NMR spectroscopy. RESULTS With overfeeding, volunteers gained 7.7 ± 1.8 kg (% change 9.8 ± 2.3). Overfeeding increased fasting NEFA, LDL-cholesterol and insulin concentrations. Indirect calorimetry showed a shift towards greater reliance on lipid oxidation. In skeletal muscle tissue, overfeeding increased ceramide content, lipid droplet content and perilipin-2 mRNA expression. Phosphorylation of AMP-activated protein kinase was decreased. Overfeeding increased mRNA expression of certain genes coding for mitochondrial proteins (CS, OGDH, CPT1B, UCP3, ANT1). Despite the stress of nutrient overload, mitochondrial content and mitochondrial respiration in muscle did not change after overfeeding. Similarly, overfeeding had no effect on either the emission of reactive oxygen species or on mitochondrial function in vivo. CONCLUSIONS/INTERPRETATION Skeletal muscle mitochondria are significantly resilient to nutrient overload. The lower skeletal muscle mitochondrial oxidative capacity in human obesity is likely to be caused by reasons other than nutrient overload per se. TRIAL REGISTRATION ClinicalTrials.gov NCT01672632.
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Affiliation(s)
- Frederico G S Toledo
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, 200 Lothrop Street, BST W1054, Pittsburgh, PA, 15261, USA.
| | | | | | - Sudip Bajpeyi
- Pennington Biomedical Research Center, Baton Rouge, LA, USA
- Department of Kinesiology, University of Texas El Paso, El Paso, TX, USA
| | - Bret Goodpaster
- Translational Research Institute for Metabolism and Diabetes, Orlando, FL, USA
| | - Kevin E Conley
- University of Washington Medical Center, Seattle, WA, USA
| | - Eric Ravussin
- Pennington Biomedical Research Center, Baton Rouge, LA, USA
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8
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Covington JD, Campbell C, Burke LW, Gardner JA. Tissue Specificity in Trisomy 22 Mosaicism: A Tale of Caution for Interpretation of Chromosomal Microarray Results. J Assoc Genet Technol 2018; 44:137-140. [PMID: 30521494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 09/10/2018] [Indexed: 06/09/2023]
Abstract
While the complete form of trisomy 22 is seemingly incompatible with life, the mosaic form is a rare syndrome associated with developmental delays, intellectual disability, and dysmorphic features. Due in part to the difficulty of analyzing chromosomal mosaicism, many instances either go undiagnosed or have their diagnosis delayed. We report a case of mosaic trisomy 22 in a diamnionic-dichorionic twin with marked growth discordance and intra-uterine growth restriction, diagnosed in a 2-year-old with developmental delays, sensorineural hearing loss, cardiac and gastrointestinal abnormalities, and osteopenia of prematurity. Evaluation with a chromosomal oligonucleotide microarray with SNP analysis did not detect any copy number variants. Fibroblast metaphase karyotype analysis from a skin biopsy, however, showed trisomy 22 which was confirmed by FISH. Follow-up peripheral blood karyotype analysis and FISH studies revealed a normal male karyotype. This case highlights an instance where classical cytogenetics from two separate tissue types can provide a diagnosis that is more cost-effective than microarray analysis in assessing pediatric developmental delay. Trisomy 22 is the second most common aneuploidy in spontaneous miscarriages and has a nondescript and variable phenotype, especially in cases of mosaicism. As such, this condition may be underdiagnosed using the current recommended testing algorithm. Chromosomal microarray is considered first tier testing in an unrecognized phenotype with whole exome or whole genome sequencing, often performed on peripheral blood, as second tier testing. Diagnoses such as mosaic trisomy 22 suggest the second tier of testing in undiagnosed cases should also include a recommendation to look at alternative tissue types.
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Affiliation(s)
- Jeffrey D Covington
- Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington, VT
| | - Calista Campbell
- Department of Pediatrics, University of Vermont Medical Center, Burlington, VT
| | - Leah W Burke
- Department of Pediatrics, University of Vermont Medical Center, Burlington, VT
| | - Juli-Anne Gardner
- Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington, VT
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9
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Covington JD, Johannsen DL, Coen PM, Burk DH, Obanda DN, Ebenezer PJ, Tam CS, Goodpaster BH, Ravussin E, Bajpeyi S. Intramyocellular Lipid Droplet Size Rather Than Total Lipid Content is Related to Insulin Sensitivity After 8 Weeks of Overfeeding. Obesity (Silver Spring) 2017; 25:2079-2087. [PMID: 29071793 PMCID: PMC5705570 DOI: 10.1002/oby.21980] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 07/05/2017] [Accepted: 07/16/2017] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Intramyocellular lipid (IMCL) is inversely related to insulin sensitivity in sedentary populations, yet no prospective studies in humans have examined IMCL accumulation with overfeeding. METHODS Twenty-nine males were overfed a high-fat diet (140% caloric intake, 44% from fat) for 8 weeks. Measures of IMCL, whole-body fat oxidation from a 24-hour metabolic chamber, muscle protein extracts, and muscle ceramide measures were obtained before and after the intervention. RESULTS Eight weeks of overfeeding did not increase overall IMCL. The content of smaller lipid droplets peripherally located in the myofiber decreased, while increases in larger droplets correlated inversely with glucose disposal rate. Overfeeding resulted in inhibition of Akt activity, which correlated with the reductions in smaller, peripherally located lipid droplets and drastic increases in ceramide content. Additionally, peripherally located lipid droplets were associated with more efficient lipid oxidation. Finally, participants who maintained a greater number of smaller, peripherally located lipid droplets displayed a better resistance to weight gain with overfeeding. CONCLUSIONS These results show that lipid droplet size and location rather than mere IMCL content are important to understanding insulin sensitivity.
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Affiliation(s)
- Jeffrey D. Covington
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
- Louisiana State University Health Sciences Center, School of Medicine, 433 Bolivar St, New Orleans, LA 70112
| | - Darcy L. Johannsen
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Paul M. Coen
- Translational Research Institute for Metabolism and Diabetes Florida Hospital • Sanford-Burnham Medical Research Institute, 301 East Princeton Street, Orlando, FL 32804
| | - David H. Burk
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Diana N. Obanda
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Philip J. Ebenezer
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Charmaine S. Tam
- The Charles Perkins Centre and The School of Biological Sciences, University of Sydney, NSW, Australia
| | - Bret H. Goodpaster
- Translational Research Institute for Metabolism and Diabetes Florida Hospital • Sanford-Burnham Medical Research Institute, 301 East Princeton Street, Orlando, FL 32804
| | - Eric Ravussin
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Sudip Bajpeyi
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
- Universtiy of Texas at El Paso, Department of Kinesiology, 500 University Ave, El Paso, TX, 79968
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10
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Bajpeyi S, Covington JD, Taylor EM, Stewart LK, Galgani JE, Henagan TM. Skeletal Muscle PGC1α -1 Nucleosome Position and -260 nt DNA Methylation Determine Exercise Response and Prevent Ectopic Lipid Accumulation in Men. Endocrinology 2017; 158:2190-2199. [PMID: 28398573 PMCID: PMC5505213 DOI: 10.1210/en.2017-00051] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 04/04/2017] [Indexed: 01/13/2023]
Abstract
Endurance exercise has been shown to improve lipid oxidation and increase mitochondrial content in skeletal muscle, two features that have shown dependence on increased expression of the peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α). It is also hypothesized that exercise-related alterations in PGC1α expression occur through epigenetic regulation of nucleosome positioning in association with differential DNA methylation status within the PGC1α promoter. In this study, we show that when primary human myotubes from obese patients with type 2 diabetes are exposed to lipolytic stimulus (palmitate, forskolin, inomycin) in vitro, nucleosome occupancy surrounding the -260 nucleotide (nt) region, a known regulatory DNA methylation site, is reduced. This finding is reproduced in vivo in the vastus lateralis from 11 healthy males after a single, long endurance exercise bout in which participants expended 650 kcal. Additionally, we show a significant positive correlation between fold change of PGC1α messenger RNA expression and -1 nucleosome repositioning away from the -260 nt methylation site in skeletal muscle tissue following exercise. Finally, we found that when exercise participants are divided into high and low responders based on the -260 nt methylation status, the -1 nucleosome is repositioned away from the regulatory -260 nt methylation site in high responders, those exhibiting a significant decrease in -260 nt methylation, but not in low responders. Additionally, high but not low responders showed a significant decrease in intramyocellular lipid content after exercise. These findings suggest a potential target for epigenetic modification of the PGC1α promoter to stimulate the therapeutic effects of endurance exercise in skeletal muscle.
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Affiliation(s)
- Sudip Bajpeyi
- Department of Kinesiology, University of Texas at El Paso, El Paso, Texas 79968
| | - Jeffrey D. Covington
- Laboratory of Skeletal Muscle Physiology, Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808
- School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112
| | - Erin M. Taylor
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana 47907
| | - Laura K. Stewart
- Rocky Mountain Cancer Rehabilitation Institute, University of Northern Colorado, Greeley, Colorado 80639
| | - Jose E. Galgani
- Pontificia Universidad Católica de Chile, Santiago 8331010, Chile
| | - Tara M. Henagan
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana 47907
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11
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Covington JD, Tam CS, Bajpeyi S, Galgani JE, Noland RC, Smith SR, Redman LM, Ravussin E. Myokine Expression in Muscle and Myotubes in Response to Exercise Stimulation. Med Sci Sports Exerc 2017; 48:384-90. [PMID: 26460627 DOI: 10.1249/mss.0000000000000787] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE Myokines have been shown to affect muscle physiology and exert systemic effects. We endeavored to investigate a panel of myokine mRNA expression after a single exercise bout (studies 1 and 2) to measure myokine mRNA in primary human myotubes in an in vitro exercise model (study 2). METHODS Vastus lateralis muscle biopsies were obtained from 20 healthy males (age, 24.0 ± 4.5 yr; BMI, 23.6 ± 1.8 kg·m)(-2) before and after a single exercise bout (650 kcal at 50% V˙O2max). Primary myotubes from active and sedentary male donors were treated with a pharmacological cocktail (palmitate, forskolin, and ionomycin (PFI)) to mimic exercise-stimulated contractions in vitro. RESULTS Interleukin 6 and 8 (IL-6 and IL-8), leukocyte-inducing factor, and connective tissue growth factor (CTGF) mRNA levels increased approximately 10-fold after a single exercise bout (all P < 0.001), whereas myostatin levels decreased (P < 0.05). Key correlations between myokine expression and parameters of muscle and whole-body physiology were found: myostatin versus skeletal muscle citrate synthase activity (r = -0.69, P < 0.001), V˙O2max (r = -0.64, P = 0.002) and the percentage of Type I fibers (r = -0.55, P = 0.01); IL-6 versus the RER (r = 0.45, P = 0.04), homeostatic model assessment of insulin resistance (r = 0.44, P = 0.05), and serum lactate (r = 0.50, P = 0.02). Myokine expressions in myotubes from sedentary donors for CTGF and myostatin decreased, whereas IL-6 and IL-8 increased after PFI treatment. In myotubes from active donors, myokine expression increased for IL-6, CTGF, and myostatin but decreased for IL-8 after PFI treatment. CONCLUSION These data offer insight into the differences in regulation of myokine expression and their possible physiologic relationships.
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Affiliation(s)
- Jeffrey D Covington
- 1Pennington Biomedical Research Center, Baton Rouge, LA; 2School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA; 3The Charles Perkins Centre and The School of Biological Sciences, University of Sydney, NSW, AUSTRALIA; 4Department of Kinesiology, University of Texas in El Paso, El Paso, TX; and 5School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, CHILE
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Abstract
The sirtuins represent a class of proteins first discovered orthologus to the yeast silent information regulator 2 protein that have been retained in mammalian species. Currently, seven sirtuins have been identified in humans, and their functions currently surpass their originally identified role as histone deacetylase and chromatin silencers to encompass nutrient sensing and metabolic function. All seven sirtuins require NAD(+) in order to carry out their enzymatic activity, and thus become activated in conditions of nutrient depletion, starvation, and cellular stress. Caloric restriction and increased physical activity have been postulated, though perhaps controversially, to mediate sirtuin function. Here, we review the current literature surrounding the functions of the seven human sirtuins, mediators of their function, and the roles they play in metabolic health related to dietary and physical activity interventions. Despite the controversy surrounding sirtuin function with regard to longevity, we have aimed to show that regardless of its effects on aging, sirtuin function is pivotal to pathways involving metabolic health, and should therefore be investigated with regard to improving metabolic diseases such as obesity and type 2 diabetes.
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Affiliation(s)
- Jeffrey D Covington
- School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Sudip Bajpeyi
- Department of Kinesiology, University of Texas at El Paso, El Paso, TX, USA
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Covington JD, Myland CK, Rustan AC, Ravussin E, Smith SR, Bajpeyi S. Effect of serial cell passaging in the retention of fiber type and mitochondrial content in primary human myotubes. Obesity (Silver Spring) 2015; 23:2414-20. [PMID: 26538189 PMCID: PMC4701579 DOI: 10.1002/oby.21192] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 04/30/2015] [Accepted: 05/18/2015] [Indexed: 01/05/2023]
Abstract
OBJECTIVE The purpose of the study was to determine the effects of passaging on retention of donor phenotypic characteristics in primary human myotubes. METHODS Primary muscle cultures and serial passaged myotubes from physically active, sedentary lean, and individuals with type 2 diabetes were established. Maximal ATP synthesis capacity (ATPmax) and resting ATP flux (ATPase) in vivo were measured by (31) P magnetic resonance spectroscopy, type-I fibers and intramyocelluar lipid (IMCL) in vastus lateralis tissue were determined using immunohistochemistry techniques, and oxidative phosphorylation complexes (OXPHOS) were measured by Western immunoblotting. Similar in vitro measures for lipid and type-I fibers were made in myotubes, along with mitochondrial content measured by MitoTracker. RESULTS Passage 4 and 5 measures for myotubes correlated positively with in vivo measurements for percent type-I fibers (P4: R(2) = 0.39, p = 0.02; P5: R(2) = 0.48, p = 0.01), ATPmax (P4: R(2) = 0.30, p = 0.03; P5: R(2) = 0.22, p = 0.05), and OXPHOS (P4: R(2) = 0.44, p = 0.04; P5: R(2) = 0.59, p = 0.006). No correlations were observed for IMCL. However, passage 4 measures for myotubes correlated with passage 5 measures for percent type-I fibers (R(2) = 0.49, p = 0.01), IMCL (R(2) = 0.80, p < 0.001), and mitochondrial content (R(2) = 0.26, p = 0.03). CONCLUSIONS Myotubes through the first two passages following immunopurification (referred to as passage 4 and 5) reflect the mitochondrial and type-I fiber content in vivo phenotype of the donor.
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Affiliation(s)
- Jeffrey D. Covington
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
- Louisiana State University Health Sciences Center, School of Medicine, 433 Bolivar St, New Orleans, LA 70112
| | - Cassandra K. Myland
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Arild C. Rustan
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Eric Ravussin
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Steven R. Smith
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Sanford-Burnham Medical Research Institute, 2566 Lee Rd, Winter Park, FL 32789
| | - Sudip Bajpeyi
- Pennington Biomedical Research Center, Laboratory of Skeletal Muscle Physiology, 6400 Perkins Road, Baton Rouge, LA 70808
- Universtiy of Texas at El Paso, Department of Kinesiology, 500 University Ave, El Paso, TX, 79968
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14
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Covington JD, Noland RC, Hebert RC, Masinter BS, Smith SR, Rustan AC, Ravussin E, Bajpeyi S. Perilipin 3 Differentially Regulates Skeletal Muscle Lipid Oxidation in Active, Sedentary, and Type 2 Diabetic Males. J Clin Endocrinol Metab 2015; 100:3683-92. [PMID: 26171795 PMCID: PMC4596049 DOI: 10.1210/jc.2014-4125] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
CONTEXT The role of perilipin 3 (PLIN3) on lipid oxidation is not fully understood. OBJECTIVE We aimed to 1) determine whether skeletal muscle PLIN3 protein content is associated with lipid oxidation in humans, 2) understand the role of PLIN3 in lipid oxidation by knocking down PLIN3 protein content in primary human myotubes, and 3) compare PLIN3 content and its role in lipid oxidation in human primary skeletal muscle cultures established from sedentary, healthy lean (leans), type 2 diabetic (T2D), and physically active donors. DESIGN, PARTICIPANTS, AND INTERVENTION This was a clinical investigation of 29 healthy, normoglycemic males and a cross-sectional study using primary human myotubes from five leans, four T2D, and four active donors. Energy expenditure, whole-body lipid oxidation, PLIN3 protein content in skeletal muscle tissue, and ex vivo muscle palmitate oxidation were measured. Myotubes underwent lipolytic stimulation (palmitate, forskolin, inomycin [PFI] cocktail), treatment with brefeldin A (BFA), and knockdown of PLIN3 using siRNA. SETTING Experiments were performed in a Biomedical Research Institute. MAIN OUTCOME MEASURES Protein content, 24-hour respiratory quotient (RQ), and ex vivo/in vitro lipid oxidations. RESULTS PLIN3 protein content was associated with 24-h RQ (r = -0.44; P = .02) and skeletal muscle-specific ex vivo palmitate oxidation (r = 0.61; P = .02). PLIN3 knockdown showed drastic reductions in lipid oxidation in myotubes from leans. Lipolytic stimulation increased PLIN3 protein in cells from leans over T2Ds with little expression in active participants. Furthermore, treatment with BFA, known to inhibit coatomers that associate with PLIN3, reduced lipid oxidation in cells from lean and T2D, but not in active participants. CONCLUSIONS Differential expression of PLIN3 and BFA sensitivity may explain differential lipid oxidation efficiency in skeletal muscle among these cohorts.
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Affiliation(s)
- Jeffrey D Covington
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Robert C Noland
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - R Caitlin Hebert
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Blaine S Masinter
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Steven R Smith
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Arild C Rustan
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Eric Ravussin
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Sudip Bajpeyi
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
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Covington JD, Bray GA, Redman LM, Johannsen DL, Ravussin E. Eight weeks of dietary overfeeding increases renal filtration rates in humans: implications for the pathogenesis of diabetic hyperfiltration. J Intern Med 2015; 278:396-400. [PMID: 25903638 PMCID: PMC4560986 DOI: 10.1111/joim.12377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Diabetic nephropathy is characterized at its onset by glomerular hyperfiltration. Prospective studies in humans measuring filtration rates with weight gain are lacking. We investigated renal filtration following weight gain induced by overfeeding. DESIGN Eight weeks of overfeeding (40% above energy requirements, 44% fat, 15% protein and 41% carbohydrate) as well as a 6-month follow-up after the overfeeding intervention. SUBJECTS Thirty-five participants (age: 26.7 ±5.3 years; body mass index: 25.5 ± 2.2 kg m(-2) ; 29 m/6f). MEASUREMENTS Creatinine clearance rate (Ccr) from 24-h urine collection, estimated glomerular filtration rate (eGFR) from the modification of diet in renal disease (MDRD), insulin sensitivity/glucose disposal rate (GDR) by a euglycemic-hyperinsulinemic clamp, components from basic metabolic panels and serum lipid panels. RESULTS Both eGFR and Ccr increased with overfeeding (P = 0.04) and serum lipids (all P < 0.05), along with a decrease in insulin sensitivity (P = 0.003). Fasting glucose concentration was not affected (P = 0.98), but the per cent change in Ccr correlated positively with the change in GDR with overfeeding (r = 0.39, P = 0.02). Six months following overfeeding, serum glucose was maintained, and no evidence of urinary glucose was observed at any time-point. CONCLUSIONS These data suggest that renal hyperfiltration may act as a mechanism to preserve insulin sensitivity through maintenance of systemic glucose homoeostasis with caloric excess.
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Affiliation(s)
- J D Covington
- Laboratory of Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA.,School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - G A Bray
- Laboratory of Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - L M Redman
- Laboratory of Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - D L Johannsen
- Laboratory of Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - E Ravussin
- Laboratory of Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA, USA
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16
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Covington JD, Bajpeyi S, Moro C, Tchoukalova YD, Ebenezer PJ, Burk DH, Ravussin E, Redman LM. Potential effects of aerobic exercise on the expression of perilipin 3 in the adipose tissue of women with polycystic ovary syndrome: a pilot study. Eur J Endocrinol 2015; 172:47-58. [PMID: 25342854 PMCID: PMC4247800 DOI: 10.1530/eje-14-0492] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Polycystic ovary syndrome (PCOS) is associated with reduced adipose tissue lipolysis that can be rescued by aerobic exercise. We aimed to identify differences in the gene expression of perilipins and associated targets in adipose tissue in women with PCOS before and after exercise. DESIGN AND METHODS We conducted a cross-sectional study in eight women with PCOS and eight women matched for BMI and age with normal cycles. Women with PCOS also completed a 16-week prospective aerobic exercise-training study. Abdominal subcutaneous adipose tissue biopsies were collected, and primary adipose-derived stromal/stem cell cultures were established from women with PCOS before 16 weeks of aerobic exercise training (n=5) and controls (n=5). Gene expression was measured using real-time PCR, in vitro lipolysis was measured using radiolabeled oleate, and perilipin 3 (PLIN3) protein content was measured by western blotting analysis. RESULTS The expression of PLIN1, PLIN3, and PLIN5, along with coatomers ARF1, ARFRP1, and βCOP was ∼ 80% lower in women with PCOS (all P<0.05). Following exercise training, PLIN3 was the only perilipin to increase significantly (P<0.05), along with coatomers ARF1, ARFRP1, βCOP, and SEC23A (all P<0.05). Furthermore, PLIN3 protein expression was undetectable in the cell cultures from women with PCOS vs controls. Following exercise training, in vitro adipose oleate oxidation, glycerol secretion, and PLIN3 protein expression were increased, along with reductions in triglyceride content and absence of large lipid droplet morphology. CONCLUSIONS These findings suggest that PLIN3 and coatomer GTPases are important regulators of lipolysis and triglyceride storage in the adipose tissue of women with PCOS.
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Affiliation(s)
- Jeffrey D Covington
- Laboratory of Reproductive Endocrinology and Woman's HealthPennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USADepartment of KinesiologyUniversity of Texas in El Paso, 500 University Avenue, El Paso, Texas 79968, USAInserm UMR 1048Institute of Metabolic and Cardiovascular Diseases and Paul Sabatier University, Toulouse, France
| | - Sudip Bajpeyi
- Laboratory of Reproductive Endocrinology and Woman's HealthPennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USADepartment of KinesiologyUniversity of Texas in El Paso, 500 University Avenue, El Paso, Texas 79968, USAInserm UMR 1048Institute of Metabolic and Cardiovascular Diseases and Paul Sabatier University, Toulouse, France
| | - Cedric Moro
- Laboratory of Reproductive Endocrinology and Woman's HealthPennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USADepartment of KinesiologyUniversity of Texas in El Paso, 500 University Avenue, El Paso, Texas 79968, USAInserm UMR 1048Institute of Metabolic and Cardiovascular Diseases and Paul Sabatier University, Toulouse, France
| | - Yourka D Tchoukalova
- Laboratory of Reproductive Endocrinology and Woman's HealthPennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USADepartment of KinesiologyUniversity of Texas in El Paso, 500 University Avenue, El Paso, Texas 79968, USAInserm UMR 1048Institute of Metabolic and Cardiovascular Diseases and Paul Sabatier University, Toulouse, France
| | - Philip J Ebenezer
- Laboratory of Reproductive Endocrinology and Woman's HealthPennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USADepartment of KinesiologyUniversity of Texas in El Paso, 500 University Avenue, El Paso, Texas 79968, USAInserm UMR 1048Institute of Metabolic and Cardiovascular Diseases and Paul Sabatier University, Toulouse, France
| | - David H Burk
- Laboratory of Reproductive Endocrinology and Woman's HealthPennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USADepartment of KinesiologyUniversity of Texas in El Paso, 500 University Avenue, El Paso, Texas 79968, USAInserm UMR 1048Institute of Metabolic and Cardiovascular Diseases and Paul Sabatier University, Toulouse, France
| | - Eric Ravussin
- Laboratory of Reproductive Endocrinology and Woman's HealthPennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USADepartment of KinesiologyUniversity of Texas in El Paso, 500 University Avenue, El Paso, Texas 79968, USAInserm UMR 1048Institute of Metabolic and Cardiovascular Diseases and Paul Sabatier University, Toulouse, France
| | - Leanne M Redman
- Laboratory of Reproductive Endocrinology and Woman's HealthPennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USADepartment of KinesiologyUniversity of Texas in El Paso, 500 University Avenue, El Paso, Texas 79968, USAInserm UMR 1048Institute of Metabolic and Cardiovascular Diseases and Paul Sabatier University, Toulouse, France
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Briand N, Prado C, Mabilleau G, Lasnier F, Le Lièpvre X, Covington JD, Ravussin E, Le Lay S, Dugail I. Caveolin-1 expression and cavin stability regulate caveolae dynamics in adipocyte lipid store fluctuation. Diabetes 2014; 63:4032-44. [PMID: 24969108 PMCID: PMC4238006 DOI: 10.2337/db13-1961] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Adipocytes specialized in the storage of energy as fat are among the most caveolae-enriched cell types. Loss of caveolae produces lipodystrophic diabetes in humans, which cannot be reversed by endothelial rescue of caveolin expression in mice, indicating major importance of adipocyte caveolae. However, how caveolae participate in fat cell functions is poorly understood. We investigated dynamic conditions of lipid store fluctuations and demonstrate reciprocal regulation of caveolae density and fat cell lipid droplet storage. We identified caveolin-1 expression as a crucial step in adipose cell lines and in mice to raise the density of caveolae, to increase adipocyte ability to accommodate larger lipid droplets, and to promote cell expansion by increased glucose utilization. In human subjects enrolled in a trial of 8 weeks of overfeeding to promote fattening, adipocyte expansion response correlated with initial caveolin-1 expression. Conversely, lipid mobilization in cultured adipocytes to induce lipid droplet shrinkage led to biphasic response of cavin-1 with ultimate loss of expression of cavin-1 and -3 and EHD2 by protein degradation, coincident with caveolae disassembly. We have identified the key steps in cavin/caveolin interplay regulating adipocyte caveolae dynamics. Our data establish that caveolae participate in a unique cell response connected to lipid store fluctuation, suggesting lipid-induced mechanotension in adipocytes.
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Affiliation(s)
| | | | - Guillaume Mabilleau
- Service Commun d'Imageries et d'Analyses Microscopiques, Université d'Angers, Angers, France
| | | | | | | | - Eric Ravussin
- Pennington Biomedical Research Center, Baton Rouge, LA
| | - Soazig Le Lay
- INSERM, UMR1063, Université d'Angers, Angers, France
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Covington JD, Tam CS, Pasarica M, Redman LM. Higher circulating leukocytes in women with PCOS is reversed by aerobic exercise. Biochimie 2014; 124:27-33. [PMID: 25446648 DOI: 10.1016/j.biochi.2014.10.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 10/31/2014] [Indexed: 12/17/2022]
Abstract
Polycystic ovary syndrome (PCOS) is characterized by insulin resistance, elevated circulating leukocytes, and hypothesized to have higher adipose tissue inflammation. Aerobic exercise reduces circulating leukocytes and improves insulin sensitivity in obese individuals, but the effect of exercise on inflammation in PCOS is not known. We investigated circulating leukocytes, insulin sensitivity by euglycemic-hyperinsulinemic clamp, serum pro- and anti-inflammatory markers (hsCRP, TNF-α, total and high molecular weight adiponectin), and abdominal subcutaneous adipose tissue (SAT) gene expression of proinflammatory markers in 8 PCOS women and 8 obese control females matched for BMI. Additionally, in a prospective study, the 8 women with PCOS underwent a 16-week aerobic exercise regimen with the same measures performed post-intervention. Compared to controls, white blood cell counts (WBC) were 30% higher (p = 0.04) and circulating total adiponectin levels were 150% lower (p = 0.03) in women with PCOS at baseline/pre-exercise conditions. SAT gene expression of macrophage migration inhibitory factor (MIF, p < 0.01) and interleukin-6 (IL-6, p < 0.05) were also lower in women with PCOS. In response to 16 weeks of aerobic exercise, insulin sensitivity improved (p < 0.01) and WBC counts decreased (p = 0.02). The exercise-induced change in WBC and circulating neutrophils correlated inversely with changes in glucose disposal rate (r = -0.73, p = 0.03; and r = -0.82, p = 0.01, respectively). Aerobic exercise reduced serum leptin (p < 0.05) after 4 weeks, trended to reduce the ratio of leptin-to-high molecular weight adiponectin (p < 0.1) by the 8th week, and significantly increased serum dehydroepiandrosterone sulfate (DHEA-S, p < 0.001) after 16 weeks. In conclusion, women with PCOS have higher circulating leukocytes compared to controls, which can be reversed by aerobic exercise and is associated with improvements in insulin sensitivity.
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Affiliation(s)
- Jeffrey D Covington
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA; Louisiana State University Health Sciences Center, School of Medicine, 433 Bolivar St, New Orleans, LA 70112, USA
| | - Charmaine S Tam
- The Charles Perkins Centre and The School of Biological Sciences, University of Sydney, 2006 NSW, Australia
| | - Magdalena Pasarica
- Translational Research Institute, Florida Hospital - Stanford-Burnam, 301 E. Princeton Street, Orlando, FL 32804, USA
| | - Leanne M Redman
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
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Johannsen DL, Tchoukalova Y, Tam CS, Covington JD, Xie W, Schwarz JM, Bajpeyi S, Ravussin E. Effect of 8 weeks of overfeeding on ectopic fat deposition and insulin sensitivity: testing the "adipose tissue expandability" hypothesis. Diabetes Care 2014; 37:2789-97. [PMID: 25011943 PMCID: PMC4170127 DOI: 10.2337/dc14-0761] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The presence of large subcutaneous adipocytes in obesity has been proposed to be linked with insulin resistance and type 2 diabetes through the "adipose tissue expandability" hypothesis, which holds that large adipocytes have a limited capacity for expansion, forcing lipids to be stored in nonadipose ectopic depots (skeletal muscle, liver), where they interfere with insulin signaling. This hypothesis has, however, been largely formulated by cross-sectional findings and to date has not been prospectively demonstrated in the development of insulin resistance in humans. RESEARCH DESIGN AND METHODS Twenty-nine men (26.8 ± 5.4 years old; BMI 25.5 ± 2.3 kg/m(2)) were fed 40% more than their baseline requirement for 8 weeks. Before and after overfeeding, insulin sensitivity was determined using a two-step hyperinsulinemic-euglycemic clamp. Intrahepatic lipid (IHL) and intramyocellular lipid (IMCL) were measured by (1)H-MRS and abdominal fat by MRI. Subcutaneous abdominal adipose and skeletal muscle tissues were collected to measure adipocyte size and markers of tissue inflammation. RESULTS Subjects gained 7.6 ± 2.1 kg (55% fat) and insulin sensitivity decreased 18% (P < 0.001) after overfeeding. IHL increased 46% from 1.5% to 2.2% (P = 0.002); however, IMCL did not change. There was no association between adipocyte size and ectopic lipid accumulation. Despite similar weight gain, subjects with smaller fat cells at baseline had a greater decrease in insulin sensitivity, which was linked with upregulated skeletal muscle tissue inflammation. CONCLUSIONS In experimental substantial weight gain, the presence of larger adipocytes did not promote ectopic lipid accumulation. In contrast, smaller fat cells were associated with a worsened metabolic response to overfeeding.
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Affiliation(s)
| | | | - Charmaine S Tam
- Pennington Biomedical Research Center, Baton Rouge, LA Charles Perkins Centre and School of Biological Sciences, University of Sydney, Sydney, New South Wales, Australia
| | | | - Wenting Xie
- Pennington Biomedical Research Center, Baton Rouge, LA
| | - Jean-Marc Schwarz
- College of Osteopathic Medicine, Touro University California, Vallejo, CA
| | - Sudip Bajpeyi
- Pennington Biomedical Research Center, Baton Rouge, LA Department of Kinesiology, University of Texas at El Paso, El Paso, TX
| | - Eric Ravussin
- Pennington Biomedical Research Center, Baton Rouge, LA
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Tam CS, Covington JD, Bajpeyi S, Tchoukalova Y, Burk D, Johannsen DL, Zingaretti CM, Cinti S, Ravussin E. Weight gain reveals dramatic increases in skeletal muscle extracellular matrix remodeling. J Clin Endocrinol Metab 2014; 99:1749-57. [PMID: 24601694 PMCID: PMC4010691 DOI: 10.1210/jc.2013-4381] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
CONTEXT In animal models of obesity, chronic inflammation and dysregulated extracellular matrix remodeling in adipose tissue leads to insulin resistance. Whether similar pathophysiology occurs in humans is not clear. OBJECTIVE The aim of this study was to test whether 10% weight gain induced by overfeeding triggers inflammation and extracellular matrix remodeling (gene expression, protein, histology) in skeletal muscle and sc adipose tissue in humans. We also investigated whether such remodeling was associated with an impaired metabolic response (hyperinsulinemic-euglycemic clamp). DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION Twenty-nine free-living males were fed 40% over their baseline energy requirements for 8 weeks. RESULTS Ten percent body weight gain prompted dramatic up-regulation of a repertoire of extracellular matrix remodeling genes in muscle and to a lesser degree in adipose tissue. The amount of extracellular matrix genes in the muscle were directly associated with the amount of lean tissue deposited during overfeeding. Despite weight gain and impaired insulin sensitivity, there was no change in local adipose tissue or systemic inflammation, but there was a slight increase in skeletal muscle inflammation. CONCLUSION We propose that skeletal muscle extracellular matrix remodeling is another feature of the pathogenic milieu associated with energy excess and obesity, which, if disrupted, may contribute to the development of metabolic dysfunction.
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Affiliation(s)
- Charmaine S Tam
- Pennington Biomedical Research Center (C.S.T., J.D.C., S.B., Y.T., D.B., D.L.J., E.R.), Baton Rouge, Louisiana 70808; The Charles Perkins Centre and School of Biological Sciences (C.S.T.), University of Sydney, Sydney, 2006 New South Wales, Australia; Department of Kinesiology (S.B.), University of Texas at El Paso, El Paso, Texas 79968; and Department of Experimental and Clinical Medicine-Obesity Center (C.M.Z., S.C.), United Hospitals-University of Ancona, Ancona 60020, Italy
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21
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Bajpeyi S, Myrland CK, Covington JD, Obanda D, Cefalu WT, Smith SR, Rustan AC, Ravussin E. Lipid in skeletal muscle myotubes is associated to the donors' insulin sensitivity and physical activity phenotypes. Obesity (Silver Spring) 2014; 22:426-34. [PMID: 23818429 PMCID: PMC3883809 DOI: 10.1002/oby.20556] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 06/17/2013] [Indexed: 12/21/2022]
Abstract
OBJECTIVE This study investigated the relationship between in vitro lipid content in myotubes and in vivo whole body phenotypes of the donors such as insulin sensitivity, intramyocellular lipids (IMCL), physical activity, and oxidative capacity. DESIGN AND METHODS Six physically active donors were compared to six sedentary lean and six T2DM. Lipid content was measured in tissues and myotubes by immunohistochemistry. Ceramides, triacylglycerols, and diacylglycerols (DAGs) were measured by LC-MS-MS and GC-FID. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp (80 mU min⁻¹ m⁻²), maximal mitochondrial capacity (ATPmax) by ³¹P-MRS, physical fitness by VO₂max and physical activity level (PAL) by accelerometers. RESULTS Myotubes cultured from physically active donors had higher lipid content (0.047 ± 0.003 vs. 0.032 ± 0.001 and 0.033 ± 0.001AU; P < 0.001) than myotubes from lean and T2DM donors. Lipid content in myotubes was not associated with IMCL in muscle tissue but importantly, correlated with in vivo measures of ATPmax (r = 0.74; P < 0.001), insulin sensitivity (r = 0.54; P < 0.05), type-I fibers (r = 0.50; P < 0.05), and PAL (r = 0.92; P < 0.0001). DAGs and ceramides in myotubes were inversely associated with insulin sensitivity (r = -0.55, r = -0.73; P < 0.05) and ATPmax (r = -0.74, r = -0.85; P < 0.01). CONCLUSIONS These results indicate that cultured human myotubes can be used in mechanistic studies to study the in vitro impact of interventions on phenotypes such as mitochondrial capacity, insulin sensitivity, and physical activity.
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MESH Headings
- Adult
- Biopsy
- Body Mass Index
- Cells, Cultured
- Ceramides/metabolism
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/pathology
- Diglycerides/metabolism
- Female
- Humans
- Insulin Resistance
- Lipid Metabolism
- Male
- Mitochondria, Muscle/metabolism
- Mitochondria, Muscle/pathology
- Motor Activity
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle Fibers, Slow-Twitch/pathology
- Obesity, Morbid/complications
- Oxidative Phosphorylation
- Oxygen Consumption
- Physical Fitness
- Triglycerides/metabolism
- Young Adult
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Affiliation(s)
- Sudip Bajpeyi
- Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Cassandra K. Myrland
- Dept. of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Jeffrey D. Covington
- Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Diana Obanda
- Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808
| | - William T. Cefalu
- Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808
| | - Steven R. Smith
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital / Sanford-Burnham Medical Research Institute, 301 E. Princeton St. Orlando, FL 32804
| | - Arild C. Rustan
- Dept. of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Eric Ravussin
- Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808
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Lecoultre V, Peterson CM, Covington JD, Ebenezer PJ, Frost EA, Schwarz JM, Ravussin E. Ten nights of moderate hypoxia improves insulin sensitivity in obese humans. Diabetes Care 2013; 36:e197-8. [PMID: 24265370 PMCID: PMC3836149 DOI: 10.2337/dc13-1350] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Covington JD, Galgani JE, Rustan AC, Zhang Z, Moro C, Smith SR, Ravussin E, Bajpeyi S. Muscle perilipin 3 is reduced using in vitro and in vivo exercise models and negatively associated with exercise lipid oxidation. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1132.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | - Cedric Moro
- Institute of Metabolic and Cardiovascular DiseasesToulouseFrance
| | | | | | - Sudip Bajpeyi
- Pennington Biomedical Research CenterBaton RougeLA
- KinesiologyUniversity at Texas at El PasoEl PasoTX
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Tam CS, Covington JD, Ravussin E. Response to Low macrophage content in diabetic and aging human skeletal muscle. Obesity (Silver Spring) 2013; 21:4-5. [PMID: 23401144 PMCID: PMC3839625 DOI: 10.1002/oby.20034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Charmaine S. Tam
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA
- The Charles Perkins Centre and School of Biological Sciences, University of Sydney, NSW, Australia
| | | | - Eric Ravussin
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA
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Johannsen DL, Galgani JE, Johannsen NM, Zhang Z, Covington JD, Ravussin E. Effect of short-term thyroxine administration on energy metabolism and mitochondrial efficiency in humans. PLoS One 2012; 7:e40837. [PMID: 22844412 PMCID: PMC3406028 DOI: 10.1371/journal.pone.0040837] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 06/16/2012] [Indexed: 11/28/2022] Open
Abstract
The physiologic effects of triiodothyronine (T3) on metabolic rate are well-documented; however, the effects of thyroxine (T4) are less clear despite its wide-spread use to treat thyroid-related disorders and other non-thyroidal conditions. Here, we investigated the effects of acute (3-day) T4 supplementation on energy expenditure at rest and during incremental exercise. Furthermore, we used a combination of in situ and in vitro approaches to measure skeletal muscle metabolism before and after T4 treatment. Ten healthy, euthyroid males were given 200 µg T4 (levothyroxine) per day for 3 days. Energy expenditure was measured at rest and during exercise by indirect calorimetry, and skeletal muscle mitochondrial function was assessed by in situ ATP flux (31P MRS) and in vitro respiratory control ratio (RCR, state 3/state 4 rate of oxygen uptake using a Clark-type electrode) before and after acute T4 treatment. Thyroxine had a subtle effect on resting metabolic rate, increasing it by 4% (p = 0.059) without a change in resting ATP demand (i.e., ATP flux) of the vastus lateralis. Exercise efficiency did not change with T4 treatment. The maximal capacity to produce ATP (state 3 respiration) and the coupled state of the mitochondria (RCR) were reduced by approximately 30% with T4 (p = 0.057 and p = 0.04, respectively). Together, the results suggest that T4, although less metabolically active than T3, reduces skeletal muscle efficiency and modestly increases resting metabolism even after short-term supplementation. Our findings may be clinically relevant given the expanding application of T4 to treat non-thyroidal conditions such as obesity and weight loss.
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Affiliation(s)
- Darcy L. Johannsen
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
| | - Jose E. Galgani
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Neil M. Johannsen
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
| | - Zhengyu Zhang
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
| | - Jeffrey D. Covington
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
| | - Eric Ravussin
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
- * E-mail:
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Abstract
In addition to adipose tissue, recent studies suggest that skeletal muscle may also be a source of low-grade inflammation, particularly in inactive and/or overweight individuals. The aim of this study was to examine the presence of macrophages in skeletal muscle from obese subjects with type 2 diabetes (T2D) before and after a 9-month exercise program (vs. a non-exercising control group) (Study 1) and in young vs. elderly subjects (Study 2). In both studies, CD68(+) macrophages in vastus lateralis biopsies were determined by immunohistochemistry and inflammation gene expression measured. Macrophage content (%) was calculated by the number of macrophages per 100 muscle fibers. In Study 1, we found relatively low numbers (2-3%) of CD68(+) macrophages in skeletal muscle in obese T2D subjects (BMI = 37.3 ± 5.2 kg/m(2)), which were unchanged after a 9-month exercise program (P = 0.42). Similarly, in Study 2 (BMI = 27.1 ± 2.5 kg/m(2)), CD68(+) macrophages were relatively low in muscle (4-5%) and were not different between young and elderly individuals (P = 0.42). However, elderly subjects had twofold higher CD68 and CD206 gene expression (both P < 0.002) than young participants. In both studies, CD68(+) muscle macrophages were not associated with BMI. In conclusion, we found little evidence of macrophage accumulation in skeletal muscle in obese T2D subjects or in elderly individuals. A 9-month exercise program was not associated with a decrease in macrophage content.
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Muoio DM, Noland RC, Kovalik JP, Seiler SE, Davies MN, DeBalsi KL, Ilkayeva OR, Stevens RD, Kheterpal I, Zhang J, Covington JD, Bajpeyi S, Ravussin E, Kraus W, Koves TR, Mynatt RL. Muscle-specific deletion of carnitine acetyltransferase compromises glucose tolerance and metabolic flexibility. Cell Metab 2012; 15:764-77. [PMID: 22560225 PMCID: PMC3348515 DOI: 10.1016/j.cmet.2012.04.005] [Citation(s) in RCA: 265] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 11/18/2011] [Accepted: 04/09/2012] [Indexed: 02/04/2023]
Abstract
The concept of "metabolic inflexibility" was first introduced to describe the failure of insulin-resistant human subjects to appropriately adjust mitochondrial fuel selection in response to nutritional cues. This phenomenon has since gained increasing recognition as a core component of the metabolic syndrome, but the underlying mechanisms have remained elusive. Here, we identify an essential role for the mitochondrial matrix enzyme, carnitine acetyltransferase (CrAT), in regulating substrate switching and glucose tolerance. By converting acetyl-CoA to its membrane permeant acetylcarnitine ester, CrAT regulates mitochondrial and intracellular carbon trafficking. Studies in muscle-specific Crat knockout mice, primary human skeletal myocytes, and human subjects undergoing L-carnitine supplementation support a model wherein CrAT combats nutrient stress, promotes metabolic flexibility, and enhances insulin action by permitting mitochondrial efflux of excess acetyl moieties that otherwise inhibit key regulatory enzymes such as pyruvate dehydrogenase. These findings offer therapeutically relevant insights into the molecular basis of metabolic inflexibility.
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Affiliation(s)
- Deborah M Muoio
- Sarah W. Stedman Nutrition and Metabolism Center, Department of Medicine, Duke University, Durham, NC 27704, USA.
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Tam CS, Covington JD, Ravussin E, Redman LM. Little evidence of systemic and adipose tissue inflammation in overweight individuals(†). Front Genet 2012; 3:58. [PMID: 22529850 PMCID: PMC3329711 DOI: 10.3389/fgene.2012.00058] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 02/29/2012] [Indexed: 12/05/2022] Open
Abstract
Context: The effect of weight loss by diet alone or diet in conjunction with exercise on low-grade inflammation in non-obese (overweight) individuals is not known. Objective: Test the hypothesis that 24 weeks of moderate calorie restriction (CR; 25%) by diet only or with aerobic exercise would reduce markers of systemic inflammation and attenuate inflammation gene expression in subcutaneous adipose tissue. Design: Randomized controlled trial. Setting: Institutional Research Center. Participants: Thirty-five overweight (body mass index: 27.8 ± 0.7 kg/m2) but otherwise healthy participants (16M/19F) completed the study. Intervention: Participants were randomized to either CR (25% reduction in energy intake, n = 12), caloric restriction + exercise (CR + EX: 12.5% reduction in energy intake + 12.5% increase in exercise energy expenditure, n = 12), or control (healthy weight-maintenance diet, n = 11) for 6 months. Main outcome measures: Fasting serum markers of inflammation [leptin, highly sensitive C-reactive protein (hsCRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), adiponectin] and inflammation-related genes [CD68, IL-6, TNF-α, macrophage migration inhibitory factor (MIF), monocyte chemoattractant protein-1 (MCP-1), adiponectin, plasminogen activator inhibitor-1 (PAI-1)] in subcutaneous adipose tissue. Results: CR and CR + EX lost similar amounts of body weight (–10 ± 1%), fat mass (–24 ± 3%), visceral fat (–27 ± 3%), and had increased insulin sensitivity (CR: 40 ± 20%, CR + EX: 66 ± 22%). Leptin was significantly decreased from baseline (p < 0.001) in both groups however TNF-α and IL-6 were not changed. hsCRP was decreased in CR + EX. There was no change in the expression of genes involved in macrophage infiltration (CD68, MIF MCP-1, PAI-1) or inflammation (IL-6, TNF-α, adiponectin) in either CR or CR + EX. Conclusion: A 10% weight loss with a 25% CR diet alone or with exercise did not impact markers of systemic inflammation or the expression of inflammation-related adipose genes in overweight individuals.
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Affiliation(s)
- Charmaine S Tam
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA
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29
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Tchoukalova YD, Fitch M, Rogers PM, Covington JD, Henagan TM, Ye J, Hellerstein MK, Ravussin E. In vivo adipogenesis in rats measured by cell kinetics in adipocytes and plastic-adherent stroma-vascular cells in response to high-fat diet and thiazolidinedione. Diabetes 2012; 61:137-44. [PMID: 22124466 PMCID: PMC3237665 DOI: 10.2337/db10-1768] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Impairment of adipogenesis contributes to the development of obesity-related insulin resistance. The current in vitro approaches for its assessment represent crude estimates of the adipogenic potential because of the disruption of the in vivo microenvironment. A novel assessment of in vivo adipogenesis using the incorporation of the stable isotope deuterium ((2)H) into the DNA of isolated adipocytes and stroma-vascular fraction from adipose tissue has been developed. In the current study, we have refined this technique by purifying the adipocytes via a negative immune selection and sorting the plastic adherent stroma-vascular (aSV) subfraction (using 3 h culture) that contains mostly adipocyte progenitor cells and ∼10% of small adipocytes. Using a 3-week 8% (2)H(2)O ingestion with a high-fat diet (HFD) or HFD plus pioglitazone (HFD-P), we demonstrate that the fractions of new aSV cells (f(aSV)) and immunopurified adipocytes (f(AD)) (the ratio of their (2)H-enrichment of DNA to the maximal (2)H-enrichment of DNA of bone marrow reference cells) recapitulate the known hyperplastic mechanism of weight gain with pioglitazone treatment. We conclude that f(aSV) and f(AD) are reliable indices of in vivo adipogenesis. The proposed method represents a valuable tool for studying the effect of interventions (drugs, diets, and exercise) on in vivo adipogenesis.
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Affiliation(s)
- Yourka D Tchoukalova
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA.
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