COMPLEX COLOCALIZATION OF CHROMOGRANINS AND NEUROHORMONES IN THE HUMAN GASTROINTESTINAL-TRACT

Co-localization of chromogranin (Cg) A, B, and C has been studied in d ifferent neuroendocrine cell types in histologically normal mucosa fro m human gastrointestinal tract (corpus, antrum, duodenum, ileum, and c olon) using single-, double-, and triple-immunofluorescence stainings. Virtually all enterochromaffin (EC) cells contained CgA, and those in the luminal two thirds of the antral mucosa and villi of small intest ine often also contained CgB. A few EC cells in the duodenal crypts co ntained CgC. Most gastrin cells harbored both CgB and CgA, although ra ther more CgB than CgA, but some gastrin cells contained all three typ es, i.e., also CgC. Some CCK cells also contained all three chromogran ins. Enteroglucagon cells in the duodenal villi contained CgA and some CgB. CgA (but not B or KEY WORDS C) was found in some secretin, GIP, enteroglucagon/peptide YY, and neurotensin cells. A chromogranin A few somatostatin cells contained CgA but neither CgB nor CgC. CgA and C w ere found chromogranin B mainly in the basal cell region, whereas CgB occurred more diffusely throughout the cytoplasm This varying distribu tion suggests that not all secretory granules contain CgA, or that CgB may occur in a nongranular form. The Varying composition of the diffe rent chromogranins may reflect their complex functional roles in the w idespread neuroendocrine system.