MicroRNAs in Psychological Stress Reactions and Their Use as Stress-Associated Biomarkers, Especially in Human Saliva

MicroRNAs (miRNAs) play a central role in the regulation of many cellular processes including physiological and psychological stress reaction pathways. Psychological stress is an important factor for the genesis and maintenance of many diseases. Several miRNAs have already been described to be involved in its regulation. The presence of miRNAs in all body fluids implies a widespread role in communication throughout the whole organism and together with their stability makes them formidable candidates as biomarkers. Alterations of stress-associated miRNA expression levels have been found in the brain and whole blood of humans and animals. In this paper, we review the participation of miRNAs in stress-reactive processes as well as their usability as salivary biomarkers of such processes. In conclusion, we suggest that salivary miRNAs may be useful as noninvasive biomarkers to assess epigenetic regulation processes of chronic or acute psychological stress reactions.