Circulating Levels of Irisin in Healthy Young Subjects

Study Overview
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Brief Summary
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Irisin, a newly discovered myokine induced in exercise, has potential effects in stimulating adipose tissue browning, fighting obesity and diabetes. No prior study has reported on the role of circulating irisin in healthy individuals in correlation with lean and fat body mass. Furthermore, the circadian and seasonal variation of irisin is largely unknown.

Detailed Description
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The main aims of this prospective study will be to investigate: 1) circulating irisin levels in healthy, young men and women according to their lean and fat mass; 2) the circadian variations of irisin levels; 3) the seasonal variations of irisin levels.

Official Title
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Circulating Irisin in Healthy Young Men and Women and Correlation With Lean Body Mass, Fat Mass and Adipocytokines. Circadian and Seasonal Variation and the Effect of Food Intake and Exercise

Conditions
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Healthy Subjects

Intervention / Treatment
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* Dietary Supplement: Boost
* Other: Aerobic exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy volunteers Exclusion Criteria: i) body mass index (BMI) above 30 or below 20 kg/m2; ii) diseases that could affect muscle or fat homeostasis; iii) medications that could affect muscle or fat homeostasis.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 25 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Healthy individuals<br>Participants will be healthy volunteers of both sexes recruited from the Greek Military Medical School personnel, Thessaloniki, Greece. | |
| Boost Subgroup<br>After an overnight fast, 40 participants will be provided a standardized mixed meal in two different quantities (125 ml, n=20 and 250 ml, n=20) and blood samples will be obtained before as well as 30 min after mixed meal ingestion | Dietary Supplement: Boost<br>* After an overnight fast, blood samples will be obtained before as well as 30 min after standardized mixed meal ingestion<br>|
| Aerobic exercise<br>After an overnight fast, 20 participants will be subjected to aerobic exercise for 30 min and blood samples will be obtained at baseline and at 30 min | Other: Aerobic exercise<br>* After an overnight fast and rest, blood samples will be obtained before as well as 30 min after aerobic exercise<br>|
| Circadian variation Subgroup<br>20 of the participants will be hospitalized and closely monitored for 24 hours. A catheter will be inserted in a vein and blood samples will be obtained every 3 hours through the 24-hour period. | |
| Seasonal variation Subgroup<br>20 of the participants will be monitored for one year and blood samples will be obtained every 3 months (at the middle of month January - April - July - October). Subjects will be instructed to maintain their normal exercise routine and dietary habits. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Irisin | After a standardized dinner and an overnight fast, a blood sample will be obtained the next morning. | 1 day | 
| irisin circadian variation | 20 participants will be hospitalized and closely monitored for 24 hours. A catheter will be inserted in a vein and blood samples will be obtained every 3 hours through the 24-hour period | 1 day | 
| irisin seasonal variation | 20 participants will be monitored for one year and blood samples will be obtained every 3 months (at the middle of month January - April - July - October). At the same intervals physical examination and BMI calculation will be conducted. Subjects will be instructed to maintain their normal exercise routine and dietary habits. | 12 months | 
| Irisin postprandial | A sub-population of 40 participants of the cohort will receive a standardized meal (Boost) in two different quantities (20 participants will receive 125 ml and 20 participants 250 ml). Serum irisin levels will be measured at baseline and 30 min postprandial. | 1 day | 
| Irisin after excercise | A sub-population of 20 participants of the cohort will be subjected to 30 min of aerobic exercise. Serum irisin levels will be measured at baseline and at 30 min. | 1 day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Irisin associates | After a standardized dinner and an overnight fast, a blood sample for adiponectin and leptin will be obtained the next morning, and body composition (total body fat mass and bone-free lean mass) will be assessed by BIA. Participants will also be asked to complete a validated questionnaire assessing their diet and exercise habits. Correlations between serum irisin levels and the above parameters will be examined | 1 day | 
| serum adipokines | After a standardized dinner and an overnight fast, a blood sample for adiponectin and leptin will be obtained the next morning. | 1 day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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irisin, adiponectin, leptin, lean body mass, fat mass