Pancreatic peptide YY in alloxan diabetic mice.

Peptide YY (PYY) immunoreactive material was detected in the splenic and duodenal portions of the adult mouse pancreas, using immunocytochemical and immunochemical methods. Cells displaying PYY immunoreactivity generally occurred at the islet periphery. Double immunostaining enabled localization of PYY to a major subpopulation of the glucagon cells and to subpopulations of the pancreatic polypeptide (PP) cells and the somatostatin cells. In contrast, no PYY immunoreactivity occurred in the insulin cells. In alloxan-treated hyperglycemic mice, PYY immunoreactive cells were increased in number and distributed throughout the islets, in parallel with the glucagon, PP, and somatostatin cells. Analysis by radioimmunoassay indicated a significant increase in the concentration of pancreatic PYY after alloxan treatment in the splenic portion of the pancreas, but not in the duodenal portion. Pancreatic glucagon concentrations were not significantly changed. It is concluded that the islet content of PYY increases in alloxan diabetes, which might contribute to the accompanying alterations in islet function.