Figure 4

Single optical stimulation in the RVM of TPH2-ChR2 mice induces persistent behaviors of pain sensitization. (A and B) Changes in sensitivity of mechanical pain (A) and thermal pain (B) before (baseline) and after single light stimulation (arrow) given for 5 min on day 0 in WT and TPH2-ChR2 mice (n =5 each group). Pain tests were performed once daily. (C) Schematic drawing of brain slices illustrating tip positions of the optical cannulas (circle, WT; triangle, TPH2-ChR2). Numbers on the right are distance from Bregma. * p <0.05, ** p <0.01, *** p <0.001 (two-way ANOVA and Bonferroni’s post hoc analysis).