Fig. 1.

Electrical stimulation (ES) decreased the mechanical threshold and increased the CGRP level in rats. a, ES induced marked mechanical face pain hypersensitivity. *p < 0.05 and **p < 0.01 vs. sham, one-way ANOVA. For animal behaviour data, N = at least 7 rats for each group. b, ES induced a significant increase in the CGRP level in the external jugular vein of rats. ***p < 0.001 vs. sham, unpaired t-test. All experiments were performed in triplicate with similar results. c, Immunostaining data indicating that ES significantly increased the protein expression of CGRP in trigeminal nucleus caudalis (TNC) sections. d, Size distribution of TG neurons isolated from sham and ES-treated groups. e, colocalization of NeuN (red) with CGRP (green) in rat TG sections from the sham and ES-treated groups. Arrows show the colocalization. Scale bars: 50 μm. f, bar graph showing the increased percentage of CGRP-positive (CGRP⁺) TG neurons in rats with ES-induced migraine. **p < 0.01 vs. sham, unpaired t-test