Obesity-associated alterations in the circadian rhythm of the myokine irisin

D Löffler; U Müller; K Scheuermann; I Wagner; D Friebe; J Gesing; A Körner

doi:10.1055/s-0034-1374952

Diabetologie und Stoffwechsel, Table of Contents

Obesity-associated alterations in the circadian rhythm of the myokine irisin

D Löffler ¹^,², U Müller ³, K Scheuermann ¹, I Wagner ¹^,², D Friebe ¹^,⁴, J Gesing ¹, A Körner ¹^,²

¹Centre for Pediatric Research, Hospital for Children and Adolescents, Dept. of Women and Child Health, University of Leipzig, Leipzig, Germany
²Leipzig University Medical Center (IFB) Adiposity Diseases, Leipzig, Germany
³Heart Center Leipzig, University of Leipzig, Leipzig, Germany
⁴Department of Molecular Cardiology, Heinrich-Heine-University, Düsseldorf, Germany

Abstract

Background: The new myokine irisin has been proposed to be secreted upon exercise to promote the browning of white adipose tissue, suggesting irisin as a treatment option for obesity and associated diseases. The proposed induction of irisin by activity is still conflicting.

Aims: In this study we wanted to asses whether a circadian rhythm, meals, glucose load or different forms of exercise cause changes in irisin serum level.

Methods: We measured irisin serum level in 5 different cohorts (children, young adults, lean, obese) which are distinguishable by the kind (ergometer, aqua-training, school sport) and duration (30 min, 6 weeks, 3 years) of physical exercise.

Results: Serum irisin does not show a circadian regulation. Furthermore, meals and standardized glucose load in oGTT had no effect on irisin. Lean males (84.4 ± 12.0 ng/ml) and obese females (88.6 ± 15.9 ng/ml) have significantly higher irisin levels than lean females (51.4 ± 7.1 ng/ml). Statistical analysis revealed positive correlations to muscle-associated BIA-parameters like body-cell-mass (r = 0.41; p = 0.001) and lean-body-mass (r = 0.49; p = 0.02).

Irisin increased by acute, short-term (15 min) exercise in children. Similarly, in young adults a 30 min short-term exercise increased irisin, but serum levels were normalised within 30 min. In contrast, longer exercise programs in obese children (6 weeks aqua-training, 6 weeks short-term obesity intervention or 3 year low grade obesity intervention) had no effect on irisin serum level. Assay specificity was verified via western blot.

Conclusion: Irisin is increased in obese and males in relation to muscle mass. Acute short-time exercise increased circulating irisin, whereas chronic exercise, meals or diurnal regulation had no effect.