Response in the brain to TPA-induced skin inflammation. Mice were treated daily with five topical applications of TPA or acetone. Samples were taken 24 hours after fifth application. (A) H & E stains of (i) TPA-treated and (ii) acetone-treated skin. Scale bar: 100 μm. Arrow points to epidermal hyperplasia. (B) Plasma concentrations of (i) IL-1β, (ii) IL-6 and (iii) TNFα. (C) Relative expression of ISGs, normalized to TBP, in brain and PBLs of TPA-treated compared to acetone-treated mice. Fold change was calculated by comparing the normalized copy number in each sample to the mean of the vehicle-injected control group. Data represent mean ± SEM; n = 5/group.