Figure 7.

Role of FLA-ST Ultrapure (flagellin), a TLR5 agonist, in CCI-induced pain hypersensitivity by an intrathecal administration. (A,C) Mechanical hyperalgesia and (B,D) mechanical allodynia were evaluated in CCI rats at POW 8 and recorded as baseline values at post-injection hour 0. Temporal changes of pain hypersensitivity on (A,B) ipsilateral and (C,D) contralateral sides were evaluated in Vehicle and various FLA-ST Ultrapure groups. Temporal patterns of (E) difference in withdrawal threshold and (F) difference in mechanical threshold demonstrated that FLA-ST Ultrapure exerted an analgesic effect on CCI-induced mechanical hyperalgesia but not mechanical allodynia, in a dose-responsive manner. The withdrawal threshold and mechanical threshold were represented as mean ± SD. Vehicle group (white squares, n = 3) was used to demonstrate the effect of intrathecal administration on behavioral assessments. The properties of FLA-ST Ultrapure (flagellin) were tested at the concentration of 0.1 μg (light blue squares), 0.3 μg (blue squares) and 0.9 μg (deep blue squares) (n = 3 per group). Statistical comparisons in Vehicle and FLA-ST Ultrapure groups were made by the two-way ANOVA, followed by Bonferroni post hoc test, with the concentrations of FLA-ST Ultrapure as between-subjects factors and time as the within-subjects factor. *** p < 0.001, indicated a significant difference.