Figure 2

Cytokine TNF-α (A), IL-1β (B), IL-6 (C) and nerve growth factor (NGF) (D) production in hindpaw skin was measured by EIA assay at various time points after intraplantar injection of 25 μg of substance P (SP). Assays were performed at 0, 1, 3, 6, 24, and 48 h. SP injection induced a significant increase in all inflammatory mediators compared to baseline levels. TNF-α (A) was elevated at just 1 h after injection (compared to controls), IL-1β (B) and IL-6 (C) cytokine levels were elevated at 1 h and 3 h post-injection, respectively, and NGF (D) levels gradually increased over 24 h post-injection, dropping to baseline at 48 h. Data are expressed as mean values (pg/mg protein) ± standard error (SE) (n = 8 per cohort) and analyzed using one-way analysis of variance (ANOVA) followed by Neuman-Keuls multiple comparison test to compare different time points. *P < 0.05, **P < 0.01 and ***P < 0.001 vs. baseline at 0 h. #P < 0.05, ##P < 0.01 and ###P < 0.001 vs. peak values.