Objective To investigate the changes of poly-ADP-ribose polymerase (PARP) and NF kappa B (NF-κB) in adenohypophysis in rat model of severe acute pancreatitis (SAP),and their role in the mechanism of adenohypophysis injury in SAP.Methods Forty Wistar rats were randomly (random number) divided into 5 groups:the sham operation group (SO group,n =8),SAP 1 h,3 h,6 h and 12 h groups (n =8 in each group).SAP model was induced by retrograde injection of 5％ sodium taurocholate into the biliopancreatic duct.Serum levels of amylase,lipase and ascites were measured.After sacrifice of experiment rats,pancreas and adenohypophysis tissues were taken for pathological examination under light microscope.Adenohypophysis cells were observed under electronic microscopy as well.PARP and NF-κB expressions in adenohypophysis cell was studied by using immunohistochemisty assay.Results After modelling,serum levels of amylase,lipase and ascites in SAP group increased gradually,which were higher than those in SO group (P ＜ 0.05).Adenohypophysis cell swelling and partial necrosis were observed under light microscope.As the time prolonged,their nuclei became dark and pyknotic more and more,and the endoplasmic reticulum and mitochondrial swelling in adenohypophysis cells were observed under electronic microscopy.The expressions of PARP and NF-κB in SAP group increased gradually,which were higher than those in SO group.Conclusions Significant pathological and ultrastructural injuries were observed in adenohypophysis cells in severe acute pancreatitis.These changes might correlate with PARP and NF-κB signaling pathway.