Cocaine- and amphetamine-regulated transcript : identification and distribution in human gastrointestinal tract.

Cocaine- and amphetamine-regulated transcript (CART) was identified in the central and peripheral nervous system, including the gastrointestinal tract of rodents and pig. CART was also expressed in neuroendocrine cells of the rats stomach antral mucosa. The knowledge of the presence and functional role of CART peptide in the human alimentary tract is very limited due to difficulties in obtaining human samples (especially from healthy individuals). The presence of CART peptide in the gastrointestinal tract of the human was investigated immunohistochemically. CART-immunoreactive (IR) neural structures were observed in all studied fragments of alimentary tract. CART-like immunoreactive nerve fibers were numerous within the muscle in layers of muscularis externa and in the myenteric plexus of all gastrointestinal segments (from esophagus to colon), while they were moderate or few in density in other layers of gastrointestinal tract. The presence of CART peptides in the neuroendocrine cells was demonstrated predominantly in the pyloric, duodenum and fundus, and only few in the rest parts of the small intestine. CART-IR neuroendocrine cells could not be detected in the mucosa of large intestine. The present study reports for the first time a detailed description of the CART distribution pattern within the human alimentary tract. Our findings may hopefully provide some contribution towards a more complete and comprehensive understanding of the function and role of the CART peptide in the alimentary system.