IMMUNOHISTOCHEMICAL LOCALIZATION OF THE PRO-PEPTIDE PROCESSING ENZYMES PC1 PC3 AND PC2 IN THE HUMAN ANAL-CANAL/

The distribution of prohormone/pro-peptide convertases PC1/PC3 and PC2 was investigated in the human anal canal by immunohistochemistry. Bot h prohormone convertases exhibited region-specific distribution patter ns and were observed in neural and neuroendocrine cells and in nonneur oendocrine cellular elements. PC1/PC3 immunoreactivity was present in enteric neurons, subsets of nerve fibers, and neuroendocrine cells, an d also in epithelial cells like intestinal stem cells, and a subpopula tion of squamous cells. Enteric neurons were PC2 immunoreactive, where as PC2 immunostaining in nerve fibers was slightly above background le vels. Few neuroendocrine cells contained PC2 immunoreactivity, which w ere located predominantly in the anal transitional zone. In the squamo us epithelium, the basal cell layer stained for PC2. The tissue specif ic distribution of PC1/PC3 and PC2 indicates region-specific processin g of peptides with regulatory functions in the anal canal and further supports the hypothesis that neuropeptides are important regulators of anal functions. (C) 1997 Elsevier Science Inc.