[Neurotensin--structure, origin and biological function]

Neurotensin is a 13-amino acid hormonal peptide which was first isolated from bovine hypothalamus. It is present in the digestive tract as well as in the central nervous system. It has a variety of biological activities as a central neurotransmitter or neuromodulator, and a peripheral hormone. NT receptors have been characterized in a variety of tissues and cell lines of peripheral and central organs. The physiological functions of NT include stimulation of pancreatic and biliary secretion, stimulation of colonic motility, inhibition of small bowel and gastric motility, trophic effect on numerous tissues of the gastrointestinal tract. NT exerts hypothermic and analgesic effect when injected into the central nervous system. From a clinical standpoint, studies with NT have led to implications of its involvement in schizophrenia, Parkinson's disease and Alzheimer's disease.