Immunohistochemical distribution of neuropeptide Y, peptide YY, pancreatic polypeptide-like immunoreactivity and their receptors in the epidermal skin of healthy women

Abstract Few studies have suggested that neuropeptide Y (NPY) could play an important role in skin functions. However, the expression of NPY, the related peptides, peptide YY (PYY) and pancreatic polypeptide (PP) and their receptors have not been investigated in human skin. Using specific antisera directed against NPY, PYY, PP and the Y 1 , Y 2 , Y 4 and Y 5 receptor subtypes, we investigated here the expression of these markers. NPY-like immunoreactivity (ir) in the epidermal skin could not be detected. For the first time we report the presence of positive PP-like ir immunofluorescent signals in epidermal cells, i.e. keratinocytes of skin from three areas (abdomen, breast and face) obtained as surgical left-overs. The immunofluorescent signal of PP-like ir varies from very low to high level in all three areas. In contrast, PYY-like ir is only expressed in some cells and with varied level of intensity. Furthermore and for the first time we observed specific Y 1 and Y 4 receptor-like ir in all epidermal layers, while the Y 2 and Y 5 subtypes were absent. Interestingly, as seen in human epidermis, in Episkin, a reconstituted human epidermal layer, we detected the presence of PP-like as well as Y 1 -like and Y 4 -like ir. These data have shown the presence and distribution of PYY, PP and Y 1 and Y 4 receptors in the human skin and Episkin, suggesting possible novel roles of NPY related peptides and their receptors in skin homeostasis.