Fig. 1

Intracisternal capsaicin injection-induced spontaneous headache-related pain behaviors. Mice were injected with capsaicin into the cisterna magna to induce headache symptoms. The spontaneous headache-related pain behaviors, locomotor activity and freezing behavior, were evaluated 90 min after capsaicin infusion. a The illustration of injection site in the cisterna magna. b The trace of body movement after saline or capsaicin injection. c The locomotor activity was calculated by the distance that mice moved (cm) in every 3 min for a total session of 30 min. Bar graph illustrates cumulated counts within 30 min. d The freezing behavior was calculated by the mice immobility time (sec) in every 3 min for a total session of 30 min. Bar graph illustrates cumulated counts within 30 min. Data are represented as mean ± SEM and were analyzed by two-way ANOVA with Bonferroni’s multiple comparison test or unpaired Student’s t-test. *p < 0.05, **p < 0.01, ***p < 0.001, comparing capsaicin and saline treated groups (N = 5 per group)