Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide belonging to the vasoactive intestinal polypeptide/glucagon/ secretin family. It is widely distributed in the body, and a variety of biological actions have been reported. Recent studies have shown that there is a family of PACAP receptors (PACAPRs), and two members of this family have been identified. Mouse PACAPR-3 is a protein of 437 amino acids that has 50% and 51% identity with rat PACAP type I and type II rec