Light and electron microscopic studies of pituitary adenylate cyclase-activating peptide (PACAP)--immunoreactive neurons in the enteric nervous system of rat small and large intestine.
Pituitary adenylate cyclase-activating peptide (PACAP)-immunoreactive (IR) neurons in the myenteric and submucosal plexus of the rat small and large intestine were examined by immunostaining with purified polyclonal antiserum against PACAP (1-15), using both light and electron microscopy. Many PACAP-IR neuronal cell bodies and fibers were found in the myenteric and submucosal plexus. Many of the PACAP-IR fibers originated from the cell bodies of the myenteric and submucosal ganglia. The ganglia were also innervated by PACAP-IR fibers. PACAP-IR fibers penetrated both the circular and longitudinal muscle layers, confirming the previous observations indicating that PACAP neurons act as motor neurons. Ultrastructural study demonstrated that PACAP-IR nerve terminals formed synaptic contacts with PACAP-IR nerve cell bodies or dendritic processes. This observation suggests that PACAP-IR neurons innervate other PACAP-IR neurons, and that PACAP neurons work as interneurons in the enteric nervous system. PACAP-IR nerve cells received not only PACAP-positive nerve terminal input also PACAP-negative nerve terminal input. It also suggests that PACAP neurons are regulated not only by PACAP-IR enteric neurons, but also by neurons originating elsewhere. Our observations support the view that PACAP-IR neurons are involved in the control of gut motility.
Nagahama
M
M
Institute for Developmental Research, Kasugai, Aichi, Japan.
Tsuzuki
M
M
Mochizuki
T
T
Iguchi
K
K
Kuwahara
A
A
D000818:Animals; D004797:Enzyme-Linked Immunosorbent Assay; D007150:Immunohistochemistry; D007420:Intestine, Large / Q000294:innervation*; D007421:Intestine, Small / Q000294:innervation*; D008297:Male; D016253:Microscopy, Immunoelectron; D009197:Myenteric Plexus / Q000737:chemistry; D009474:Neurons / Q000737:chemistry*; D010455:Peptides / Q000032:analysis; D011817:Rabbits; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone / Q000032:analysis*; D013368:Submucous Plexus / Q000737:chemistry; D013569:Synapses / Q000648:ultrastructure
D010455:Peptides; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone