Figure 2.

TRPV1-positive sensory neurons but not TRPV1 channels are involved in itch evoked by SL-NH₂ plus acid. (a) Itch-related behaviors in mice were determined as in Figure 1(c) but with a TRPV1 antagonist, AMG9810 (100 µM), injected together with SL-NH₂. First injection: SL-NH₂ (7 mM) and AMG9810 (100 µM) in saline (50 µl); second injection: SL-NH₂ (14 mM), AMG9810 (100 µM), and acid (1.2% acetic acid, v/v) in saline (25 µl). (b) Itch-related behaviors determined by scratching bouts in 5-min bins during the 30-min test period following injection of SL-NH₂ plus acid into the rostral back/neck of control (Ctrl, filled) or RTX-pre-treated (RTX ablated; 100 µg/ml RTX in 50 µl 0.05% ascorbic acid and 7% Tween 80, open symbols) mice. Data are means ± SEM; n = 7–8. ***P < 0.001, Ctrl vs. RTX-ablated, by two-way repeated measures ANOVA. Group, F(1, 90) = 504.597, P < 0.001; time, F(5, 90) = 92.187, P < 0.001; interaction, F(5, 90) =71.342, P < 0.001. (c) Area under curve (AUC, scratching bout × min) calculated from the same set of data in (b). ***P < 0.001, Ctrl vs. RTX-ablated, by unpaired Student’s t test. N.S.: not significant difference, ***P < 0.001, first vs. second, paired Student’s t test. N.S.: not significant difference, ^###P < 0.001, WT vs. ASIC3-KO, unpaired Student’s t test.