Effects of neurotensin on the transit of gastrointestinal contents in the rat.

In this study the influence of neurotensin on gastric emptying, transit of gastrointestinal contents and ileo-cecal emptying was studied in the conscious rat. A bolus of radioactive marker was deposited in the gastrointestinal lumen and was monitored at different time intervals during its passage along the bowel. Gastric emptying was inhibited in a dose-dependent manner by i.v. infusion of 6 and 12 (p less than 0.01) pmol x kg-1 x min-1 of neurotensin. The transit of the gastrointestinal contents was retarded by 3 (p less than 0.001) and 6 (p less than 0.001) pmol x kg-1 x min-1. In addition, at 12 pmol x kg-1 x min-1 the distribution of the radioactivity was spread out and the radioactive front migrated farther. Infusion of 6 pmol x kg-1 x min-1 of neurotensin also produced spreading of the radioactivity in the intestine with proximal pooling and rapid migration of the front of the radioactive bolus (p less than 0.001). Ileo-cecal emptying was inhibited by neurotensin at 6 pmol x kg-1 x min-1, with pooling of the radioactivity proximal to the ileo-cecal valve (p less than 0.001). These data indicate that neurotensin prolongs the transit time of the chyme in the stomach and small intestine. Thus, neurotensin may facilitate thorough digestion of the chyme in the small intestine and enhance the absorption of nutrients.