Figure 5

GAD65-mediated analgesia is reversed by the GABA A receptor antagonist bicuculline. (A) Six days after injection of AdGAD65 into the trigeminal ganglion, a second injection was performed with saline, bicuculline or CGP46381 (a GABAB receptor antagonist), and the orofacial formalin test was carried out 10 minutes later. Bicuculline, but not CGP46381 reversed the AdGAD65-mediated analgesia in the second phase of the formalin test (RM ANOVA: F = 2.7; P < 0.001). AdGAD65 + bicuculline vs AdGAD65 + saline: **P < 0.01, ***P < 0.001. (B) Comparison of the averaged pain behavior in the second phase of the formalin test shows a significant difference between groups (one-way ANOVA: F = 15.6; P < 0.001). AdGAD65 produced a significany decrease in pain behavior. Bicuculline reverses AdGAD65-mediated analgesia. Bicuculline alone does not affect pain behavior. AdGAD65 or AdGAD65 + saline vs. AdGFP: ***P < 0.001; AdGAD65 or AdGAD65 + saline vs AdGFP: ###P < 0.001; AdGAD65 + saline vs. AdGAD65 + bicuculline: *P < 0.05.