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

• Published in: International Journal of Obesity Vol. 38; no. 5; pp. 707 - 713
• Main Authors: Besse-Patin, A, Montastier, E, Vinel, C, Castan-Laurell, I, Louche, K, Dray, C, Daviaud, D, Mir, L, Marques, M-A, Thalamas, C, Valet, P, Langin, D, Moro, C, Viguerie, N
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2014; Nature Publishing Group
• Subjects: 631/80/86; 692/698/1671/1668/1973; 692/699/2743/393; Adipose tissue; Adult; Aerobic capacity; Apelin; Autocrine signalling; Biological and medical sciences; Biopsy; Body fat; Calcium; Cyclic AMP; Cytokines; Diabetes mellitus; Diet; Endurance sports; Epidemiology; Exercise; Fibroblast growth factors; Fibroblast Growth Factors - metabolism; Fibronectins - metabolism; Fitness training programs; Gene expression; Glucose; Glucose tolerance; Growth factors; Health aspects; Health Promotion and Disease Prevention; Homeostasis; Humans; Insulin; Insulin Resistance; Intercellular Signaling Peptides and Proteins - metabolism; Interleukin 6; Interleukin-6 - metabolism; Internal Medicine; Male; Medical sciences; Medicine; Medicine & Public Health; Metabolic Diseases; Metabolism; Muscle contraction; Muscle Fibers, Skeletal - metabolism; Muscle, Skeletal - metabolism; Muscles; Musculoskeletal system; Myoblasts; Myostatin; Myostatin - metabolism; Myotubes; Obesity; Obesity - metabolism; Obesity - prevention & control; original-article; Overweight persons; Paracrine signalling; Physical Endurance; Physical exercise; Physical fitness; Physical training; Physiological aspects; Plasma levels; Public Health; Sensitivity analysis; Skeletal muscle; Subcutaneous Fat - metabolism; Up-Regulation; France; exercise; skeletal muscle cells; myokines; apelin; Physical exercise; Human; Obesity; Nutrition; Nutrition disorder; Metabolic diseases; Male; Identification; Gene expression; Striated muscle; Cell; Nutritional status
• ISSN: 0307-0565; 1476-5497; 1476-5497
• DOI: 10.1038/ijo.2013.158

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.