SLC1A2 and major depressive disorder: A microarray analysis of samples of the ACC (BA24) and the dorsolateral PFC (BA9 and BA46) from people with MDD showed reduced expression of the genes coding for the high-affinity glutamate transporters glial excitatory amino acid EAAT1 and EAAT2 along with decreased expression of glutamine synthetase, the enzyme that converts glutamate to glutamine.138 These results were subsequently extended to the locus coeruleus139 and hippocampus.140 It is not immediately clear from these studies whether the decrease in glutamate transporter expression was driven by a reduction in glial cell number.