Does diabetic state affect co-localization of peptide YY and enteroglucagon in colonic endocrine cells?

Abstract

Changes in the numbers of PYY- and enteroglucagon-immunoreactive cells in colon of animal models of human diabetes have been reported. As these peptides co-localize in the same cells it is possible that the observed changes are a result of changes in co-localization. Animal models of human type 1 and type 2 diabetes, namely the non-obese diabetic (NOD) mouse and the obese (ob/ob) mouse, were studied. As controls for the NOD mice, BALB/cJ mice were used and for ob/ob mice, homozygous lean (+/+) mice were used. Tissue samples from colon were double-immunostained for PYY and enteroglucagon according to the indirect immunofluorescence method. Co-localization of enteroglucagon and PYY was found in colonic endocrine cells in all groups investigated. Compared with controls, pre-diabetic NOD mice showed a decreased proportion of enteroglucagon/PYY co-localization. There was no difference in diabetic NOD mice or diabetic ob/ob mice when compared with controls. Whereas the number of cells containing solely enteroglucagon and solely PYY increases in pre-diabetic NOD mice, production of enteroglucagon in PYY-immunoreactive cells decreases. Although the numbers of PYY and enteroglucagon cells have been reported to be changed in both diabetic NOD mice and in obese mice, the balance between co-expressing and mono-expressing cells seems to be preserved.