Fig. 3
a Dura mater, C57 BL/6 wild-type and TRPA1 knocked out mouse. b Dura mater, TRPV1 knocked out mouse. c Trigeminal ganglion, C57 BL/6 wild-type and TRPA1 knocked out mouse. d Trigeminal ganglion, TRPV1 knocked out mouse. Normalized CGRP release after pre-incubation with butterbur root extract (petasin concentrations 30 μg/mL, n = 8 each; except for trigeminal ganglia of TRPV1 knocked out mice, n = 7) for 1 h. Stimulation steps with 5 × 10− 4 M mustard oil (a and c: minutes 10–15 for C57 BL/6 wild-type and TRPA1 knocked out mice, or minutes 20–25 for TRPV1 knocked out mice). Stimulation steps with 5 × 10− 7 M capsaicin (b and d: minutes 20–25 for C57 BL/6 wild type and TRPA1 knocked out mice, or minutes 10–15 for TRPV1 knocked out mice); other steps with SIF incubation (minutes 5–10 and 15–20); *p < 0.05, **p < 0.01, ***p < 0.001