Distribution of neurotensin in the canine gastrointestinal tract.

The distribution of immunoreactive neurotensin in the canine gastrointestinal tract from the esophagus to the rectum, as well as in the pancreas, was determined by a specific neurotensin radioimmunoassay. Immunoreactive neurotensin was found throughout the gastrointestinal tract and in the pancreas. The highest concentrations of immunoreactive neurotensin were found in the mucosal extracts of the jejunum (422 +/- 68 ng/gm) and ileum (3025 +/- 289 ng/gm). Small but substantial amounts of immunoreactive neurotensin were found in the esophagus, fundus (includes fundus and corpus), antrum, duodenum, colon, and pancreas. The concentrations of neurotensin in the mucosal extracts of the jejunum and ileum increased in a graded fashion from the proximal jejunum to the distal ileum. The neurotensin concentration in extracts of the seromuscular layers of jejunum (73 +/- 14 ng/gm) and ileum (187 +/- 38 ng/gm) were statistically higher in comparison with other gut loci.