IL6 and major depressive disorder: Elevation of peripheral proinflammatory cytokine IL-6 has been reported in clinical depression by a number of studies.5, 6, 7 Also, a recent report demonstrated increased IL-6 levels in the brain from rats that exhibited a depression-like phenotype after chronic stress paradigms.10 In line with these results, we found upregulation of Il6 in the PFC of the FSL.