Background: In migraineurs pituitary adenylate cyclase activating peptide1-38 (PACAP1-38)
is a potent migraine provoking substance and the accompanying long lasting flushing
suggests degranulation of mast cells. Infusion of the closely related vasoactive intestinal
peptide (VIP) either induces headache or flushing. This implicates the pituitary adenylate
cyclase activating peptide type I receptor (PAC1) to be involved in the pathophysiology
of PACAP1-38 provoked headaches. Here we review studies characterizing the effects
of mainly PACAP but also of VIP on cerebral and meningeal arteries and mast cells.