Fig. 3

Enhanced mechanically evoked spinal nociceptive withdrawal reflexes (NWRs) in CIA rats. The plantar surface of hind paws were mechanically stimulated with von Frey hairs, and evoked biceps femoris (BF) EMG responses were recorded. a Representative raw EMG traces recordings BF muscle in CIA and control rats stimulated with different von Frey hairs. b Stimulus-response curve of EMG response versus mechanical stimulus intensity at different time points post CIA immunization. c AUC analysis of the time course of the overall reflex response to von Frey hairs of increasing intensity in control and CIA rats (d). Time course of the BF mechanical thresholds in control and CIA rats. Time course of CIA-associated mechanical hypersensitivity (panel e left) significantly correlated with the time course of the change in BF mechanical thresholds (panel e right). Time course of CIA-induced hind paw swelling (panel e left) did not correlate with the time course of the BF mechanical thresholds (panel e right). Values are the mean ± SEM of 6 (day 0), 7 (day 4), 9 (day 7) and 8 (day 13) rats per group. ***p < 0.001, **p < 0.01, *p < 0.05 versus controls, two-way RM-ANOVA, post hoc Tukey’s test. In b, statistical analysis performed with AUC analysis and t test. In correlations studies in e and f, data were analysed with a Pearson correlation