Diagnostic: miR-134 is downregulated in patients with MDD in comparison to healthy controls (79% sensitivity and 84% specificity), bipolar and schizophrenic patients (79% sensitivity and 76.5 specificity). Therapeutic: Blocking miR-134 in vivo ameliorated neuronal structural abnormalities, biochemical changes and depression-like behaviors. Inhibition of miR-134-5p together with the use of a GR antagonist and SIRT-1 agonist depression susceptibility induced by prenatal dexamethasone exposure (PDE) in offspring rats could be prevented. Here, NR3C1 is linked to major depressive disorder.