Immunohistochemical Study on the Innervation of the Chicken Pancreas by Pituitary Adenylate Cyclase-Activating Polypeptides (PACAPs)-Containing Nerves

Pituitary adenylate cyclase-activating polypeptide (PACAP), a member of secretin/glucagon/VIP family, has a potent action on the pancreatic secretion in mammals. The present study aimed to clarify the distribution of neural elements containing PACAP27 or 38 in the chicken pancreas. These two peptides were detected in the neural elements and showed the similar distributional pattern in the chicken pancreas. Intrapancreatic ganglia containing PACAPs-immunoreactive cells were found in the interlobular connective tissue. Nerve fibers showing immunoreactivity for PACAPs made the dense network around arterioles and were distributed in lamina propria of secretory ducts and the exocrine pancreas. Double labeling immunohistochemistry for PACAPs and islet hormones revealed that PACAPs-immunoreactive nerve fibers were in contact with B and D cells in B islets, but rarely distributed in A islets. These data suggest that PACAPs have relation to the regulation of the secretion from exocrine tissue and B and D cells in B islets of the chicken pancreas.