sentences:  Research has shown that administration of intravenous PACAP-38 (two species of PACAP have been identified, one that is 38 amino acids long and one that is 27 amino acids long) triggers delayed "migraine-like headaches" in most subjects who experience migraine headaches.Treatments with monoclonal antibodies are being developed targeting PACAP or its receptors for the treatment of primary headache disorders.These include