PACAP neuropeptide, which belongs to the vasoactive intestinal polypeptide (VIP)/glucagon/secretin family. PACAP exists in two forms: Studying Pituitary adenylate cyclase-activating peptide 38 (PACAP38), which consists of 38 amino acids and PACAP27 which contains 27 amino acids at its N-terminus. PACAP38 is implicated in migraine pathophysiology however PACAP27 is not studied well. Therefore, the investigators will study PACAP27's effect on extra- and intracerebral arteries assessed by MRA on healthy volunteers.
