GAD1 and major depressive disorder: Thus, CUMS-induced depression is likely caused by a chain reaction of the stress, the upregulated miRNA-15b-5p, miRNA-144-3p, miRNA-582-5p and miRNA-879-5p, the downregulated mRNAs that encode GAD-67, VGAT and GAT-3 as well as the impaired GABA uptake and synthesis (Figure 6).