In agreement, we further found that E. coli infection induced a transient increase (after 1 and 6 h) in brain levels of the pro-inflammatory cytokine tumor necrosis factor α (TNF-α) (Fig. 2c), whereas levels of interleukin 1β (IL-1β) were comparable between groups at the evaluated timepoints (Fig. 2d). This evidence concerns the gene TNF and escherichia coli infection.