LOCALIZATION OF MOTILIN-IMMUNOPOSITIVE CELLS IN THE RAT INTESTINE BY LIGHT-MICROSCOPIC IMMUNOCYTOCHEMISTRY

Motilin-immunopositive cells (Mo cells) are known to exist in the uppe r small intestine of many species including man. However, the was foun d not to cross-react with motilin in the rat gastrointestine. The pres ent study was designed to investigate the distribution of Mo cells in the rat gastrointestine by the peroxidase-conjugated second antibody m ethod using newly raised chicken anti-motilin serum (CPV3). This antis erum was suggested to recognize the N-terminal region of the motilin m olecule by enzyme-linked immunosorbent assays and immunocytochemical a bsorption test. Mo cells detected in the rat gastrointestine by immuno cytochemistry were found to be distributed in the duodenum (1.5 cells/ mm(2)), jejunum (2.2 cells/mm(2)), and ileum (0.028 cells/mm(2)), and no positive cells were found in the gastric body, gastric antrum, cecu m, colon, or pancreas. The immunopositive cells in the rat intestine w ere spindle shaped or polygonal, scattered throughout the epithelium o f the villi and crypts, and similar to those commonly observed in the upper small intestine of other species. These results indicate for the first time that motilin-immunopositive cells do exist in the rat inte stine.