[Immunocytochemical demonstration of nitric acid synthase in rat pancreatic tissue]

To investigate the age-related alterations of pancreatic distribution of nitric oxide synthase in rats, we applied light microscopic immunocytochemistry. Tissue samples were obtained from the pancreata of 5-day-old rat newborns and 120-day-old adult rats and processed for immunocytochemistry using anti neuronal nitric oxide synthase primary serum with the avidin-biotin-streptavidin complex method. Nitric oxide synthase immunopositive intrinsic nerve cells and perivascular/periacinar nerve fibers could be seen in both the newborn and the adult rat pancreas. In addition to the labelled neuronal structures we detected some immunoreactive acinar cells in the newborns, while the neonatal ductal epithelium and the islet cells were immunonegative. Strong staining for nitric oxide synthase was observed in the adult ductal epithelial cells and moderate positivity was displayed by the adult islet cells. The localization of nitric oxide shows age-related changes mainly in the non-neuronal structures of the rat pancreas: these findings could form the morphological base of pancreatic dysfunctions in the aged.