Environmental control of microRNAs in the nervous system: Implications in plasticity and behavior

The discovery of microRNAs (miRNAs) a little over 20 years ago was revolutionary given that miRNAs are essential to numerous physiological and physiopathological processes. Currently, several aspects of the biogenic process of miRNAs and of the translational repression mechanism exerted on their targets mRNAs are known in detail. In fact, the development of bioinformatics tools for predicting miRNA targets has established that miRNAs have the potential to regulate almost all known biological processes. Therefore, the identification of the signals and molecular mechanisms that regulate miRNA function is relevant to understanding the role of miRNAs in both pathological and adaptive processes. Recently, a series of studies has focused on miRNA expression in the brain, establishing that their levels are altered in response to various environmental factors (EFs), such as light, sound, odorants, nutrients, drugs and stress. In this review, we discuss how exposure to various EFs modulates the expression and function of several miRNAs in the nervous system and how this control determines adaptation to their environment, behavior and disease state.