Amylin Coexisting With Peptide YY (PYY) and Amylin/PYY Cells Correspond to Subpopulations of Glucagon- and Glucagon-Like Peptide-1-Immunoreactive Cells in the Japanese Eel (Anguilla japonica) Pancreas.

The distribution of amylin-like substances was investigated by immunohistochemistry in the pancreas of the Japanese eel (Anguilla japonica). Amylin-immunoreactive cells were observed in pancreatic islets. These immunostaining profiles were not observed by the preabsorption of the anti-amylin serum with synthetic amylin, indicating that the serum specifically recognized eel amylin-like peptide. Almost all amylin-immunoreactive cells were immunopositive for peptide YY, suggesting that amylin and peptide YY co-secreted from the islet cells might participate in the modulation of insulin and glucagon secretion in the pancreatic islets. In addition, weakly glucagon-immunopositive cells, but not densely glucagon-immunopositive cells, also corresponded to amylin-immunoreactive cells. The subpopulation of glucagon-immunoreactive and glucagon-like peptide-1-immunoreactive cells was also immunopositive for peptide YY. These results suggest that amylin and peptide YY, and also presumably glucagon-like peptide-1, are co-secreted from the amylin/peptide YY cells, and these three peptides modulate food intake through the central nervous system in addition to intrainsular functions.