The role of PACAP and its vasodilatory properties related to migraine are supported by previous findings showing that intravenous infusion of PACAP38 dilates extracerebral arteries [11–14], as well as induces headache in healthy volunteers (100%) [12, 13] and migraine attacks in people with migraine (58–73%) [12, 14]. This evidence concerns the gene ADCYAP1 and migraine disorder.