Fig. 2.

Arthritic mice have increased density of CGRP + , TH + and GAP43 + nerve fibers in the ankle joint. Representative confocal images of CGRP (A, cyan), TH (B, purple) and GAP43 (C, yellow) in ankle-joint sections (20 μm-thick) from naïve and serum injected WT and Tlr4^−/− male and female mice. Significantly greater densities of CGRP⁺ (D), TH⁺ (E), and GAP43⁺ (F) nerve fibers were quantitated in WT serum injected compared to naïve males (p = 0.46; p = 0.003; p = 0.005 respectively) and females (p = 0.007, p = 0.0003, p = 0.0005 respectively). Male Tlr4^−/− serum injected mice had a significant increase in the density of CGRP⁺ (D; p = 0.03), but not TH⁺ (E; p = 0.10) fibers and GAP43⁺ (F; p = 0.14) fibers, compared to naïve controls. Female Tlr4^−/− serum injected mice had a significant increase in the density of GAP43⁺ (F; p = 0.0046), but not in CGRP⁺ (p = 0.38) or TH.⁺ fibers (p = 0.12) compared to naïve controls. *p < 0.05 one-way ANOVA with Tukey post hoc test (n = 4–8 per group)