Adding support for a central role for glutamate, glutamate transporter downregulation has been observed in postmortem neocortical MDD micro-arrays (e.g., SLC1A2 , SLC1A3, and L-glutamate-ammonia ligase ) (Choudary et al. 2005). In the locus ceruleus, glial-expressed high-affinity glutamate transporters (SLC1A2, SLC1A3, and GLUL) are downregulated, while neuronal presynaptic vesicular glutamate transporters (SLC17A6/VGLUT2) and postsynaptic glutamate receptors (GRIA1, GRIK1, GRM1, and GRM5) are upregulated in MDD vs. BD and non-depressed controls (Bernard et al. 2011), suggesting both regional and diagnostic specificity.
