Neurotensin is a neuropeptide that is distributed throughout the CNS and in enteroendocrine cells of the small intestine that has diverse biological activities. In vivo, neurotensin (10-50 μg per hour, i.c.v.) induces hypothermia in rats. Neurotensin signaling is increased and induces analgesia in wild-type mice, and neurotensin knockout mice are defective in basal nociceptive and stress-induced analgesic responses in a cold water swim stress test. It acts as an indirect dopamine antagonist that inhibits dopamine-induced effects at pre- and postsynaptic dopamine receptors. Neurotensin inhibits small bowel motility and secretion of gastric acid, stimulates pancreatic and biliary secretion, increases fatty acid absorption, and stimulates growth of the stomach, colon, pancreas, and small bowel in rats. It also increases growth of breast, pancreatic, and hepatocellular carcinoma cells via induction of IL-8 secretion and activation of epithelial mesenchymal transition (EMT) in vitro and in vivo.