Vasoactive intestinal peptide ( VIP ) and pituitary adenylyl cyclase-activating polypeptide ( PACAP ) are two structurally-related neuropeptides with widespread expression in the central and peripheral nervous systems .
B-GeneOrGeneProduct I-GeneOrGeneProduct I-GeneOrGeneProduct O B-GeneOrGeneProduct O O B-GeneOrGeneProduct I-GeneOrGeneProduct I-GeneOrGeneProduct I-GeneOrGeneProduct O B-GeneOrGeneProduct O O O O O O O O O O O O O O O O