SLC6A4 and major depressive disorder: In a mouse model of depression, baicalein reduces hippocampal microglia activation by inhibiting the NF-κB pathway, reduces pro-inflammatory cytokine expression, increases SLC6A4/SERT concentrations, and improves glutamate metabolism, thereby reducing depression-like behavior in open-field tests, elevated cross maze, forced swimming test, and tail suspension test (Du et al., 2019).