Original Article | Published:

Effect of endurance training on skeletal muscle myokine expression in obese men: identification of apelin as a novel myokine

International Journal of Obesity volume 38, pages 707713 (2014) | Download Citation

Abstract

Background:

It has been suggested that the metabolic benefits of physical exercise could be mediated by myokines. We examined here the effect of exercise training on skeletal muscle expression of a panel of myokines in humans. Pathways regulating myokine expression were investigated in human myotubes.

Methods:

Eleven obese non-diabetic male subjects were enrolled in an 8-week endurance training program. Insulin sensitivity was assessed by an oral glucose tolerance test. Subcutaneous adipose tissue and Vastus lateralis muscle biopsy samples were collected before and after training. RNAs were prepared from adipose tissue and skeletal muscle. Primary culture of myoblasts was established.

Results:

As expected, exercise training improved aerobic capacity and decreased fat mass. No significant change in interleukin 6, fibroblast growth factor 21, myostatin (MSTN) or irisin mRNA level was found in muscle after training. A twofold increase in apelin mRNA level was found in muscle but not in adipose tissue. No change in circulating myokine and adipokine plasma levels was observed in the resting state in response to training. Interestingly, apelin was significantly expressed and secreted in primary human myotubes. Apelin gene expression was upregulated by cyclic AMP and calcium, unlike the other myokines investigated. Importantly, changes in muscle apelin mRNA levels were positively related to whole-body insulin sensitivity improvement.

Conclusion:

Collectively, our data show that exercise training upregulates muscle apelin expression in obese subjects. Apelin expression is induced by exercise signaling pathways and secreted in vitro in human primary myotubes, and may behave as a novel exercise-regulated myokine with autocrine/paracrine action.

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Acknowledgements

We are very grateful to the staff of Toulouse Clinical Investigation Centre and to the study participants. This study was supported by grants from the National Research Agency ANR-12-JSV1-0010-01 (CM) and ANR-09-GENO-0018-01 (DL), European Federation for the Study of Diabetes/Novo Nordisk and Société Francophone du Diabète (CM), Inserm DHOS Recherche Translationnelle and AOL Hôpitaux de Toulouse (DL), Fondation pour la Recherche Médicale (DL), Inserm DHOS Recherche Translationnelle 2009 (CT, DL), AOL 08 163 02 Hôpitaux de Toulouse (CT, DL) and Glaxo Smith Kline (DL).

Author information

Author notes

    • C Moro
    •  & N Viguerie

    These authors contributed equally to this work.

Affiliations

  1. Inserm, UMR1048, Obesity Research Laboratory, I2MC, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France

    • A Besse-Patin
    • , E Montastier
    • , K Louche
    • , L Mir
    • , M-A Marques
    • , C Thalamas
    • , D Langin
    • , C Moro
    •  & N Viguerie
  2. University of Toulouse, UMR1048, Paul Sabatier University, Toulouse, France

    • A Besse-Patin
    • , E Montastier
    • , C Vinel
    • , I Castan-Laurell
    • , K Louche
    • , C Dray
    • , D Daviaud
    • , L Mir
    • , M-A Marques
    • , C Thalamas
    • , P Valet
    • , D Langin
    • , C Moro
    •  & N Viguerie
  3. Nutrition and Clinical Biochemistry Departments, Toulouse University Hospitals, Toulouse, France

    • E Montastier
    • , P Valet
    •  & D Langin
  4. Inserm, UMR1048, Adipolab, I2MC, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France

    • C Vinel
    • , I Castan-Laurell
    • , C Dray
    •  & D Daviaud
  5. Clinical Investigation Centre Inserm, CIC-9302, Department of Clinical Pharmacology, Toulouse University Hospitals, Toulouse, France

    • C Thalamas

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Competing interests

The authors declare no conflict of interest.

Corresponding author

Correspondence to N Viguerie.

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DOI

https://doi.org/10.1038/ijo.2013.158

Supplementary Information accompanies this paper on International Journal of Obesity website (http://www.nature.com/ijo)

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