Figure 6

Blocking ERK activation with U0126 attenuates the scratching behaviors induced by histamine and DNFB but not chloroquine. (A, B) The number of scratches induced by histamine treatment (500 μg) is dramatically reduced by intrathecal administration of U0126 10 min before histamine injection (A, B). The number of scratches in every 5 min is shown (A) and the total number in 30 min period is shown (B). (C) The number of scratches induced by histamine treatment (500 μg) is dramatically reduced by intrathecal administration of U0126 10 min after histamine injection. (D, E) A similar effect by U0126 is also observed in repeated DNFB-painted mice. (F) Compared with controls, the number of scratches induced by chloroquine treatment (200 μg) is unchanged after intrathecal injection of U0126. In each group, at least 5 mice were used (A-F). (G) Western blot shows the pERK expression in the spinal cord is increased in histamine-treated mice, but this increase was suppressed by the intrathecal administration of U0126. n = 3 for each group. One way ANOVA, for A, B, D, F, G; P < 0.01 in A, B, D, G; Student’s t-test for C and E; * P < 0.05; **P < 0.01).