OPA1 and migraine disorder: Namely, NTG, a vasodilator which provokes migraine via nitric oxide mechanisms [38, 39, 41] and PACAP, a vasodilatory and inflammatory neuropeptide which provokes migraine via the PAC1 or VPAC receptors [40], are the ones that seem to most commonly provoke PS, whereas CGRP less so [40], though it has a high affinity for provoking migraine-like headache in patients with migraine [42].