ABSTRACT
Neurotensin is a 13-amino acid polypeptide produced by neurons of the ileum, as well as endocrine N-cells. Its release is stimulated by fatty acids, and it reduces ileal blood flow and motility.
Substance P (pain) is a polypeptide containing 11 amino acid residues that is found in the intestine, various peripheral nerves, and several parts of the CNS. It is one of a family of six mammalian polypeptides called tachykinins that differ at the amino terminal end, but have in common a 4 amino acid carboxyl terminal sequence. Substance P is found in neurons and endocrine EC1 cells of the GI tract, and it may enter the circulation. Unlike neurotensin, it increases small intestinal motility.
