Figure 5

Attenuation of bilateral masseter muscle allodynia by TRPV1 antagonist. Experimental design of intrahippocampal injection of TRPV1 antagonists (A). The head withdrawal threshold was not different between groups with intrahippocampal injection of 5-iodo-resiniferatoxin (0.1 or 0.5 nmol) and vehicle injected group before induction of masseter muscle inflammation (p > 0.05). Significant decrease in head withdrawal threshold 4 days after CFA injection in both ipsilateral and contralateral masseter confirmed the development of allodynia (B, C). The attenuation of allodynia of ipsilateral masseter was observed 30 min, 45 min and 60 min after intrahippocampal injections of 5-iodo-resiniferatoxin (B) and in all time points in contralateral masseter (C). Data are presented as means ± s.e.m., n = 6. * p < 0.05; ** p < 0.01; *** p < 0.001 versus vehicle group at the same time point, using two-way ANOVA followed by Bonferroni post- hoc.