Αcute Exercise Alters the Levels of Human Saliva miRNAs Involved in Lipid Metabolism

The response of micro-ribonucleic acid (miRNA) expression to exercise has not been studied in saliva, although saliva combines non-invasive collection with the largest number of miRNA species among biological fluids and tissues. Thus, the purpose of this study was to investigate the effect of acute exercise on the expression of 8 human saliva miRNAs involved in lipid metabolism. 19 healthy, physically active men (VO2 max, 40.9 +/- 1.6mL<bold>kg</bold>(-1) <bold>min</bold>(-1), mean +/- se) performed a 50-min interval exercise program on stationary bicycle (spinning). Saliva samples were collected before and after exercise for miRNA expression analysis by real-time polymerase chain reaction. Statistically significant (p<0.05) changes after exercise were found in 2 of the 8 miRNAs, namely, hsa-miR-33a (fold change, 7.66 +/- 2.94;p=0.012), which regulates cholesterol homeostasis and fatty acid metabolism in the liver, and hsa-miR-378a (fold change 0.79 +/- 0.11,p=0.048), which regulates energy homeostasis and affects lipogenesis and adipogenesis. These alterations may contribute to our understanding of physiological responses to exercise and the therapeutic potential of exercise against cardiovascular disease, obesity, and the metabolic syndrome. Moreover, our findings open the possibility of noninvasively studying miRNAs that regulate the function of specific organs.