Fourth Military Medical University, Institute of Neurosciences, Xi'an.
Pituitary adenylate cyclase activating polypeptide(PACAP) is a new bioactive polypeptide originally isolated from ovine hypothalamus. It is widely distributed in the central and peripheral nervous systems, and some non-nervous tissues as well. Mediated by PACAP receptors, it stimulates adenylate cyclase and subsequently increases the cAMP level in target cells. PACAP is not only a new type of hypophysiotropic hormone, but also functions as a neurotransmitter and neuromodulator. In addition, it plays a role in paracrine and autocrine regulation of certain types of cells.