Figure 4

pERK expression and scratches in DNFB-painted mice. (A, B) Severe skin lesions are seen in mice treated with repeated DNFB painting (B), but not in control mice with repeated acetone painting (A). (C, D) Hematoxylin/eosin staining reveals irregular hyperplasia (triangles), enhanced staining of eosinophilic fibers and variable numbers of inflammatory cells (arrows) in the dermis of DNFB-treated skin samples (D), but not in those treated with acetone alone (C). (E, F) pERK is expressed in the dorsal horn of mice treated repeatedly with DNFB (F), but not with acetone (E). Comparison of scratches in 30 min between the two groups is shown in (G). Student’s t-test; **P < 0.01; n = 5 for each group. The upper diagram indicates the detailed procedure for DNFB painting, behavior observation and immunostaining conducted in (A-G). (H) Comparison of scratching number between the mice treated with 4 times of DNFB and those treated with 3 time of acetone and one time of DNFB. Significant differences are not seen in the first 2 h, but are present in the second and third 2 h as well as one week later. Two way repeated ANOVA; P < 0.01; One way ANOVA for comparison at individual time points; **P < 0.01; n = 5 for each group. The diagram shows the detailed procedure for DNFB and acetone painting, and behavior observation performed in (H). DH, dorsal horn. Scale bars, 200 μm (C, D) and 100 μm (E, F).