Cholestasis induces murine hepatocyte apoptosis and DNA synthesis with preservation of the immediate-early gene response

Background. Major hepatic resection in patients with unrelieved obstructive jaundice carries an increased risk of postoperative liver failure. We hypothesized that cholestasis induces hepatocyte apoptosis and impairs hepatic regeneration by inhibiting up-regulation of the known immediate-early response genes, nuclear factor kappa B (NF-kappaB) and activating protein-1 (AP-1). The aim of this study was to determine whether the immediate-early gene response in hepatic regeneration remains intact in extrahepatic cholestasis. Methods. Eight-week-old BALB/c mice underwent either sham operation (SO) or common bile duct ligation (BDL). Two-thirds partial hepatectomy (PH) was performed at 4 and 7 days, with remnant liver harvested 0, 15, 30, or 60 minutes after PH. Serum analysis for markers of cholestasis and histopathology was obtained. Proliferating cell nuclear antigen and terminal deoxyuridine triphosphate nick end labeling (TUNEL) immunohistochemistry for detection of DNA synthesis and apoptosis, respectively, was performed 4, 7, or 10 days after SO or BDL. Liver samples from 0, 15, 30, or 60 minutes after PH were analyzed for XF-kappaB and AP-1 DNA binding activity by using electrophoretic mobility shift assays. Results. Increased serum bilirubin level and hematoxylin-eosin-stained liver sections confirmed cholestasis in BDL mice. BDL induced marked DNA synthesis and hepatocyte apoptosis in prehepatectomy liver at both 4 and 7 days. Substantially higher basal levels of both NT-kappaB and AP-1 binding activity were present in BDL compared with SO mice. Fold induction of NT-kappaB and AP-1, however was similar between BDL and SO mice. Cholestasis induced hepatocyte DATA synthesis and apaptosis. Basal AT-kappaB and AP-1 DNA binding activity was increased in BDL mice, but fold induction of these immediate-early genes did not differ from controls. Conclusions. Although basal AT-kappaB and AP-1 DNA binding is increased in cholestasis, the immediate-early gene response to PH remains intact in BDL mice.