IRISIN IN HEALTHY YOUNG INDIVIDUALS: ASSOCIATION WITH GENDER, EXERCISE, DIET AND BODY COMPOSITION: DAY-NIGHT RHYTHM AND THE EFFECT OF FOOD INTAKE AND EXERCISE.

ANASTASILAKIS, Athanasios D.; POLYZOS, Stergios A.; SARIDAKIS, Zacharias G.; KYNIGOPOULOS, Georgios; SKOUVAKLIDOU, Elpida; VASILOGLOU, Maria F.; APOSTOLOU, Aggeliki; KARAGIOZOGLOU-LAMPOUDI, Thomai; SIOPI, Aikaterina; MOUGIOS, Vasileios; CHATZISTAVRIDIS, Panagiotis; PANAGIOTOU, Grigorios; MOLYVAS, Dimitrios; FILIPPAIOS, Andreas; DELAROUDIS, Sideris; MANTZOROS, Christos S.

PURPOSE: Myokine irisin may increase energy expenditure and affect metabolic disorders. We aimed to evaluate the association between irisin and gender, exercise, diet and body composition, and its day-night rhythm. MATERIALS AND METHODS: Observational, cross-sectional, cohort study with an additional 24h prospective observational arm (Day-night rhythm sub-study) and two prospective interventional arms (Mixed meal sub-study and Exercise sub-study) executed in the Military School of Combat Offi cers, Thessaloniki, Greece. Healthy, young students of the Military School of Combat Offi cers, Thessaloniki, Greece were subjected to anthropometric and body composition measurements (lean body mass and fat mass) and completed questionnaires regarding their eating and physical activity behavior. Sub-groups were subjected to 24h monitoring, standardized meal ingestion and 30 min aerobic exercise. Main outcome measures were circulating levels of irisin, leptin, adiponectin, insulin and related biochemical parameters RESULTS: Ιrisin levels were signifi cantly lower in males than females (72.5 ± 6.4 vs. 100.8 ± 6.3 ng/ mL, p=0.02) after adjustment for lean body mass, which was its major determinant. Irisin secretion followed a day-night rhythm (p<0.001) with peak at 9 pm. Irisin levels increased at the end of exercise (105.8 ± 14.3 vs. 84.1 ± 10.0; p<0.001), but signifi cance was lost after adjustment for changes in creatinine and CPK. Irisin levels were not affected by food intake or consumption patterns nor after a standardized meal. CONCLUSIONS: In healthy, young individuals circulating irisin is correlated with lean body mass but not with adipokines or insulin resistance. There is a day-night rhythm of irisin secretion. Exercise increases acutely circulating irisin levels, but food intake has no effect on them.

Balkan Military Medical Review, 2014, Vol 17, p313

1107-6275

Academic Journal