Salivary irisin is induced by strenuous exercise stimulus and correlates with circulating irisin.

Physical activity can increase the circulating level of irisin, fostering several beneficial effects on health. This exercise-induced myokine is generally analyzed in blood, but its collection is invasive and exposes to potential risks. Substitution of saliva sample for blood would represent a less invasive method for irisin detection. However, a limited number of studies evaluated the amount of irisin in saliva samples.3,4 Our purpose was to verify whether saliva could represent an alternative sample in which detecting irisin changes induced by an exogenous stimulus. Five active healthy adults (age: 29±14yrs; mean body mass index: 22,9±3,7kg/m²; mean peak oxygen uptake 54,0±16,5ml/kg/min) performed an incremental exercise until exhaustion on a cycle ergometer and their blood and saliva samples were collected before the exercise, 15min, 24h, 48h post-exhaustion. Irisin levels were determined using ELISA Assay Kit (#EK-067-29). Incremental exercise has determined consistent changes in irisin levels. Indeed, serum and salivary irisin levels increased from baseline to 24h post-exercise, and then returned to basal level after 48h of rest. A significant difference of serum irisin levels at 15min (p≤0,01) and 24h (p≤0,001) compared to baseline was found. Moreover, a significant correlation (r=0,92, P<0,05) was found between irisin percentage change in serum and saliva from baseline to 24h post-exercise. The findings, while preliminary, indicate that collecting saliva samples represents a valid and sensitive method of detecting irisin level changes in response to exercise. [ABSTRACT FROM AUTHOR]