New insights into the central PACAPergic system from the phenotypes in PACAP- and PACAP receptor-knockout mice

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a structurally highly conserved neuropeptide and displays pleiotropic activity, including functioning as a neurotransmitter, neuromodulator, and neurotrophic factor. A series of recent experiments, including genetic manipulation of PACAP and its receptors, has led to better understanding of both normal and pathological processes in which PACAP has been proposed to play a role, and sheds light on previously uncharacterized functions of endogenous PACAP. The aim of this article is to briefly review the recent advances in understanding the role of PACAP in the central nervous system from PACAP- and PACAP receptor-deficient mice, particularly with respect to behavioral and neurological features, including psychomotor behavior, feeding, stress responses, memory performance, ethanol sensitivity, chronic pain, and circadian rhythms. This article also discusses their potential involvement in human diseases.