Expression of cocaine- and amphetamine-egulated transcript in the pancreas of the European bison

Cocaine- and amphetamine-regulated transcript (CART) is a recently discovered neuropeptide thought to mainly act in most laboratory mammals and humans as anorexigenic factor. The expression of CART in wild living animals is barely known. In the present study immunohistochemical stainings were applied to identify CART-immunoreactive (IR) structures in the pancreas of European bison. Antibodies against neuronal marker Hu C/D were used to visualize intrapancreatic neurons. The expression of CART was detected in approx. 75% of Hu C/D-IR intrapancreatic neurons which may thus also act as interneurons. Additionally, in most intrapancreatic ganglia single CART-IR non-varicose nerve fibers running between neurons were found. Pancreatic blood vessels as well as intralobular ducts were sparsely innervated with CART-IR nerve fibers. Moderately numerous CART-IR nerve terminals were found to innervate the pancreatic endocrine and exocrine tissue. None of islet endocrine cells showed the expression of CART. No presence of CART-IR neuronal elements were found in external connective tissue capsule and septa penetrating inside to the organ. Our study is the first to outline the presence of some differences in CART-ergic innervation pattern of the pancreas between domestic and wild mammals. The lack of CART-IR endocrine islet cells in the pancreas of European bison is an interesting finding, nevertheless its significance is largely unknown at the moment and needs to be further investigated.