Figure 2

TRPV1-mediated aversion to capsaicin during oral cancer progression (A) Timeline for the two-bottle drinking assay using the oral cancer xenograft mouse model. Baseline water consumption using vehicle water (0.01% EtOH) was recorded prior to cancer cell injection into the tongue. (B) Tumor-bearing female athymic nude mice demonstrate greater aversion to 1 µM capsaicin in the drinking water compared to sham at 3 and 4 weeks post inoculation. We measured water consumed by cage; each cage housed 3 mice; each dot represents a cage of three female mice. Time x treatment, p = 0.0013. *p < 0.05, **p < 0.01 (C) There was a similar reduction in total consumption with cancer progression in tumor-bearing mice regardless of time and treatment. p > 0.05. (D) Standard CPA box in which mice were conditioned with either saline or 500 nM capsaicin oral swabbing on post inoculation days 22–24. Place aversion was measured on day 25 and CPA was assessed as the difference in time spent in the capsaicin-paired chamber compared to saline-paired chamber. (E,F) Tumor-bearing female mice (white and red bars) spent less time in the capsaicin-paired chamber compared to baseline. Time x treatment p = 0.0056, *p < 0.05, **p < 0.01. Capsaicin treatment had no effect in sham female mice. Time x treatment p = 0.1207.