PITUITARY ADENYLATE-CYCLASE ACTIVATING POLYPEPTIDE IS EXPRESSED IN AUTONOMIC NEURONS

Pituitary adenylate cyclase activating polypeptide (PACAP) is a novel vasoactive intestinal peptide (VIP)-like peptide, which is present in neuronal elements of several peripheral organs, and thus a putative ne urotransmitter/modulator. In the present study, the expression of PACA P in two parasympathetic ganglia (otic, sphenopalatine) and one mixed parasympathetic/sensory ganglion (jugular-nodose) in rat was character ized by use of in situ hybridization and immunocytochemistry and compa red to that of VIP and calcitonin gene-related peptide (CGRP). PACAP a nd VIP were expressed in virtually all nerve cell bodies in the otic a nd sphenopalatine ganglia; PACAP and VIP were also expressed in subpop ulations of nerve cell bodies in the jugular-nodose ganglion. CGRP was expressed in numerous nerve cell bodies in the jugular-nodose ganglio n and in a few, scattered, nerve cell bodies in the sphenopalatine gan glion. In the otic and sphenopalatine ganglia, PACAP- and VIP-like imm unoreactivities were frequently co-localized; in the jugular-nodose ga nglion, PACAP-like immunoreactivity was frequently co-localized with C GRP-like immunoreactivity in presumably sensory neurons and to a lesse r extent with VIP in parasympathetic neurons. Thus, PACAP is synthesiz ed and stored in autonomic parasympathetic neurons as well as in vagal sensory neurons, which provides an anatomical basis for the diverse e ffects of PACAP previously described.