Figure 5.

Reduced expression and function of TRPM8 following paclitaxel treatment. (A) Representative photomicrographs of TRPM8 immunofluorescence staining on day 14 after Veh and PTX treatment. (B) Statistical analysis of the number of TRPM8-positive neurons in the fixed area (1 μm²). Data were analyzed using a t-test. * p < 0.05, n = 5, 4. (C) Western blot analysis of TRPM8 protein levels in DRGs on day 14 after Veh and PTX treatment. TRPM8 expression was normalized to β-actin expression. Histograms show the relative amount of TRPM8 protein in Veh and PTX-treated rats. The data were analyzed using an unpaired t-test. *** p < 0.001, n = 5. (D,F) The response of DRG neurons to menthol was significantly reduced in the PTX-treated group compared with the Veh-treated group. (D) Representative images of the calcium signals in DRG neurons isolated from Veh and PTX-treated rats after menthol (200 μM) stimulation. White arrows indicate the DRG neurons responsive to menthol. (F) Statistical analysis of the F340/F380 ratio in the Veh and PTX groups following menthol stimulation. Data were analyzed using a two-way ANOVA followed by Bonferroni post hoc tests (3 independent experiments). *** p < 0.001, n = 26, 22. (E,G) The response of DRG neurons to WS-12 (a selective agonist of TRPM8) was significantly decreased in the PTX-treated group compared with the Veh-treated group. (E) Representative calcium images of DRG neurons isolated from Veh- and PTX-treated rats after WS-12 (10 μM) stimulation. White arrows indicate the DRG neurons responsive to WS-12. (G) Statistical analysis of the F340/F380 ratio following WS-12 stimulation. Data were analyzed using a two-way ANOVA followed by Bonferroni post hoc tests, 3 independent experiments, *** p < 0.001, n = 7, 16. Scale bars in (D,E) represent 100 μm. Veh: vehicle, PTX: paclitaxel, BL: baseline.