Fig. 1
a Dura mater, rat. b Trigeminal ganglion, rat. Normalized CGRP release after pre-incubation with butterbur root extract (petasin concentrations 3, 10, 30, 100 μg/mL, n = 6 each) compared to pre-incubation with the vehicle ethanol (n = 12) for 1 h. Stimulation steps with 5 × 10− 4 M mustard oil (minutes 10–15 min) or 5 × 10− 7 M capsaicin (minutes 20–25); other steps with SIF incubation (minutes 5–10 and 15–20); *p < 0.05, **p < 0.01, ***p < 0.001