Acute, but not chronic, hyperalgesia induced by nitroglycerin is blocked by sumatriptan. Male and female C57BL/6J mice were treated every other day for 9 days with nitroglycerin (10 mg/kg, i.p.), and 1h15min later with vehicle (0.9% saline) or sumatriptan (0.6 mg/kg i.p.). A) Basal mechanical responses, assessed prior to nitroglycerin administration, significantly decreased in both vehicle and sumatriptan groups during the treatment period. B) Post-treatment mechanical responses, assessed 45 min after sumatriptan/vehicle injection (2h post-nitroglycerin), indicate that nitroglycerin produces an acute hyperalgesia (vehicle group) which is significantly inhibited by sumatriptan. (n=11/group, 2-way RM ANOVA and Holm-Sidak post-hoc analysis. p<0.001 for drug, time and interaction; ***p<0.001 as compared to vehicle. This figure was previously published by Pradhan et al., Characterization of a novel model of chronic migraine, Pain, 155 (2):269-274; http://journals.lww.com/pain/pages/articleviewer.aspx?year=2014&issue=02000&article=00010&type=abstract.