Cocaine- and amphetamine-regulated transcript (CART) is expressed in the ovine pancreas

Indirect immunohistochemistry was applied to demonstrate the presence of cocaine- and amphetamine-regulated transcript (CART) peptide expression in the pancreas of the sheep. Using double immunocytochemical staining, the co-incidence of vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY) or substance P (SP) in CART-immunoreactive (IR) nerve fibers and intrapancreatic neurons was analyzed. Immunoreactivity to CART was detected in endocrine cells predominantly localized at the islet periphery. The exocrine pancreas and blood vessels were intensively innervated by CART-IR nerve fibers. Moderate numbers of CART-IR nerve terminals were found in the connective tissue, while the ductal system and islets were poorly supplied with CART-IR nerve endings. No islet penetrating CART-IR nerve fibers were detected. Approximately 53.7±1.8% of intrapancreatic neurons displayed immunoreactivity to CART and pancreatic ganglia were moderately supplied with CART-IR nerve fibers. Dependent upon the pancreas region, CART-IR nerve fibers showed a varying degree of co-existence of SP, VIP or NPY. CART-IR intrapancreatic neurons very frequently co-localized with SP, moderately with VIP and rarely with NPY. We conclude that abundant immunoreactivity to CART in the ovine pancreas and the co-existence of CART with other regulatory peptides may reflect a possible involvement of CART in hormone and enzyme secretion as well as regulation of pancreatic blood flow.