Figure 4

5-HT depletion in the RVM prevents the development of contralateral hyperalgesia. RNAi of Tph-2 in the RVM prevents the development of CFA-induced contralateral hyperalgesia. A. Western blot analysis of Tph-2 in the RVM. CFA (0.05 ml; 1:1 oil/saline) injected unilaterally into the masseter muscle 3 days after shRNA administration. Tph-2 protein expression was measured in rats at 4 day (n=4), 6 days (n=4) and 8 days (n=4) after shRNA was administered. Tph-2 protein expression was measured in rats given control shRNA (n=4) 4 days after the shRNA was administered. B, C. Immunohistochemical fluorescent staining of 5-HT in the Vi/Vc of shRNA treated rats (n=3) 24 h after CFA administration shows decreased 5-HT expression in the Vi/Vc following Tph-2 depletion in rats as compared to control shRNA (n=3). CFA was administered 3 days after shRNA administration. (Ba: control shRNA, 10x; Bb: control shRNA,40x. Ca: Tph-2 shRNA,10x; Cb: Tph-2 shRNA,40x). D, E. Mechanical hyperalgesia was tested in 5-HT depleted rats with CFA-induced hyperalgesia. Control or Tph-2 shRNA was administered and CFA was injected 3 days after. Mechanical hyperalgesia was inhibited in 5-HT depleted rats as compared to control on the contralateral side (D), but not the ipsilateral side (E). *: CFA + Tph-2 shRNA vs. CFA + control shRNA, p<;0.05; **: p<;0.01; ***: p<;0.001 (ANOVA with repeated measures and Student Neuman-Keuls post-hoc test).