Fig. 3.
Involvement of endothelin-1 signaling in tongue mechanical sensitivity after squamous cell carcinoma (SCC) cell inoculation. (A) Blotting example of endothelin-1 protein in the squamous cell carcinoma culture medium. (B) Sequential changes in the amount of endothelin-1 protein in the vehicle- and squamous cell carcinoma cell–inoculated tongue. The data represent means ± SD (n = 6 in each; Student’s t tests). (C) Endothelin-A receptor expression in cultured squamous cell carcinoma cells (a) and in trigeminal ganglion neurons innervating the vehicle- or squamous cell carcinoma cell–inoculated tongue (b). Arrows indicate 4′,6-diamidino-2-phenylindole (DAPI)– or FluoroGold (FG)-labeled endothelin-A receptor-immunoreactive cells. (D) Changes in the cancerous tongue mechanical head-withdrawal reflex threshold after BQ123 tongue administration. The data represent means ± SD (vehicle + BQ123: n = 5, squamous cell carcinoma + vehicle: n = 5, squamous cell carcinoma + BQ123: n = 7; one-way and two-way ANOVA followed by Bonferroni’s multiple-comparison tests). (E) Changes in the tongue mechanical head-withdrawal reflex threshold after endothelin-1 tongue administration. The data represent means ± SD (vehicle: n = 8, endothelin-1: n = 8; one-way and two-way ANOVA with repeated measures followed by Bonferroni’s multiple-comparison tests). “Pre” indicates before inoculation.