Distribution of enteric neural peptide YY in the dog gastrointestinal tract

Various regions of the dog gastrointestinal tract were investigated for the distribution of peptide YY (PYY) neurons using immunocytochemistry and radioimmunoassay. PYY neurons that encircled non-PYY-immunoreactive neurons were mainly observed in the myenteric plexus from the stomach to the colon. There was more PYY-like immunoreactivity in the muscle layer of the stomach and ileum than in the other intestines. The results of high performance liquid chromatography revealed that neural PYY-immunoreactive substance is identical to authentic PYY. PYY was not localized in the cholinergic neurons. These results indicate that PYY, as a neuropeptide, is involved in the regulation of gastrointestinal function.