The importance of bile and pancreatic juice for fat-induced release of neurotensin-like immunoreactivity (NTLI) from the small intestine of the rat.

The aim of the present study in the rat was to localize the gastrointestinal site(s) of NTLI release and to investigate the importance of bile and pancreatic juice for fat-induced NTLI release. Administration of Intralipid (2 ml) into the stomach and oleic acid (0.5 ml) into the duodenum increased the plasma concentration of NTLI (p-NTLI). The increase in p-NTLI levels occurred only when the jejunum and ileum were exposed to Intralipid but not when the exposure was limited to the stomach and duodenum. Exclusion of pancreatic juice significantly reduced the p-NTLI response and exclusion of both bile and pancreatic juice completely abolished the p-NTLI response to duodenally-administered oleic acid. The results indicate that neurotension is released by a direct luminal exposure of the neurotensin containing N-cells to fatty acids. It seems probable that fatty acids have to be transformed to a micellar form in order to release NTLI.