Figure 3

Aδ- and C-fiber responses in the toes after mid-plantar RTX injection. The infrared diode laser was used to stimulate Aδ- or C-fibers in the toes of the same rats used in Figure 2. (A-D) Responses to Aδ stimuli are diminished for up to 10 weeks. Plots are similar to those in Figure 2. (E) For 50 ng RTX only, a small but significant difference was measured in the toes at 5 weeks (but not at 10 weeks) for C responses; data reported are an average of 3 test days. Our initial protocol used C-fiber testing only at the mid-plantar footpad; however, since we observed prolonged, diminished Aδ behavioral responses in toes after RTX-treatment, a suppression of C-fiber behavioral responses might occur in tandem. During a separate study, we found that within 1 week after 50 ng intraplantar RTX, rats reached the 16 sec cutoff when testing C-fibers in their toes. 2-way ANOVA with repeated measures was used to compare the effect of 5 ng or 50 ng RTX versus vehicle. 2-way ANOVA was used to compare the effects of 5 ng versus 50 ng. *,† p < 0.5, **,†† p < 0.01, ***,††† p < 0.001, n = 6 rats per group.