SLC18A2 and major depressive disorder: VMAT2 mediates the uptake of monoamines, including 5-HT, from the cytoplasm into the synaptic vesicle (Henry et al., 1998) and inhibition of VMAT2 by reserpine–and the ensuing vesicular monoamine depletion and loss of regulation of quantal neurotransmitter release–has long been known to induce a depression-like phenotype (Frize, 1954; Iritani et al., 2006).