Peptide YY-like immunoreactivity in normal colon mucosa, muscle layer and adenocarcinoma

Peptide YY (PYY)-like immunoreactivity was detected in the mucosa and muscle layer of normal human colon and rectum and in well to moderately differentiated adenocarcinoma derived from the mucosa of the colon and rectum, using a sensitive and specific radioimmunoassay for PYY. The content of PYY-like immunoreactivity in the mucosa was markedly higher than those in the muscle layer and adenocarcinomatous tissue of any part of the colon and rectum. A high concentrations of PYY-like immunoreactivity was demonstrated throughout the colon mucosa (ascending colon 94.14 +/- 15.34 pmol/g, transverse colon 137.19 +/- 13.44 pmol/g, descending colon 168.89 +/- 15.63 pmol/g, and sigmoid colon 223.69 +/- 35.31 pmol/g), the highest being observed in the rectum (313.15 +/- 45.90 pmol/g). The major molecular form of PYY-like immunoreactivity both in the mucosa and muscle layer of normal human colon and rectum and in adenocarcinomatous tissue was judged by gel exclusion chromatography to be identical to pure porcine PYY. This study revealed the presence of PYY-like immunoreactivity not only in normal tissue of the colon and rectum but also in adenocarcinomas with the same elution pattern, and the mucosal concentrations of PYY-like immunoreactivity were found to be increasing distally throughout the colon and rectum.