Location of 5-HT and 5-HT4R Immunoreactivities
in Colonic Epithelial Cells
To identify enterochromaffin cells, immunostaining with two types of
5-HT markers (polyclonal rabbit anti 5-HT and monoclonal mouse anti
5-HT) was performed which showed 100% co-localization in all sections
of the colon. Immunostaining of monoclonal mouse anti 5-HT with both
enzyme-induced epitope retrieval and heat-induced epitope retrieval
showed similar results (P = 0.965). This verified the reliability of the
mouse 5-HT antibody. 5-HT and 5-HT4R-positive cells were
completely co-localized in the colonic epithelium in all sections. They
were both scattered amongst other epithelial cells in transverse
(Figures 4A,B), descending (Figure 4C), sigmoid colons (Figure 4D) and
rectum (Figure 4E), mainly in the bottom crypts. A number of
5-HT-positive cells dispersed in the lamina propria were
5-HT4R negative (Figure 4B). These are likely mucosal
5-HT-positive mast cells.