AMYLIN-CONTAINING CELLS IN THE GASTROENTEROPANCREATIC (GEP) ENDOCRINESYSTEM OF THE RAT AND HUMANS - AN IMMUNOHISTOCHEMICAL STUDY

Amylin (Islet Amyloid Polypeptide, IAPP)-containing cells were immunoh istochemically investigated in the pancreas and gastrointestinal tract of the rat and humans with reference to its co-existence with gut hor mones. Immunoreactivity for amylin was found in pancreatic islets and in endocrine cells dispersed in the pyloric antrum. The major populati on of islet cells in the rat was immunoreactive for amylin, being iden tified as B and D cells. Weak immunoreactivity for calcitonin gene-rel ated peptide (CGRP) was recognizable in the rat B cells as reported pr eviously. However it disappeared when the CGRP antiserum was pretreate d with amylin, suggesting that the CGRP antiserum might have cross-rea cted with an amylin molecule contained in the B cells. Amylin-immunore active cells in the pyloric antrum corresponded to gastrin (G) cells i n rats and also in humans. This is in contrast to a previous study sho wing the amylin immunoreactivity in non-G cells of the human pyloric a ntrum. The amylin immunoreactivity in the pancreatic islets was recogn ized in rat fetuses, whereas in the pyloric G cells it first appeared on day 28 after birth. Immunohistochemistry at the electron microscopi c level demonstrated that amylin was localized in the secretory granul es of B, D and G cells.