Expression of glutamine synthetase by mRNA is down-regulated in the dorsolateral PFC, premotor cortex and the amygdala of depressed patients (Sequeira et al., 2009) and microarray analysis of specific areas of MDD patient-cerebral cortex show down-regulation of SLC1A2 and SLC1A3, two glial high-affinity glutamate transporters (Choudary et al., 2005). Here, SLC1A2 is linked to major depressive disorder.