Figure 3.

Effects of tadalafil on STZ-induced cold hypersensitivity and TRPA1 sensitization. Mice were administered with saline or STZ (50 mg/kg, i.p.) for seven consecutive days. Two weeks after the administrations, the PDE-5 inhibitor tadalafil (10 mg/kg, i.p.), which is a vasodilator, or its vehicle was administered 1 h before the behavioral tests. (a) Skin blood flow of the hindpaw was measured and expressed as the percentage of the saline-treated nondiabetic group injected with vehicle. n = 6. (b) Cold-escape behavior scores for the cold-plate test. n = 12. (c) Duration(s) of nocifensive behavior (licking) evoked by intraplantar injection of 0.05% AITC was measured for 5 min. n = 11–13. Data are expressed as means ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001.

AITC: allyl isothiocyanate; STZ: streptozotocin.