Cellular changes in hepatocytes and intestinal endothelium after hepatoduodenal ligament occlusion and protective effects of caspase inhibition.

INTRODUCTION

Hepatic vascular control is used by many surgeons to prevent massive hemorrhage during hepatectomy. However, this may carry a risk of ischemic damage to the hepatocytes. Another major drawback of intraoperative occlusion of the hepatoduodenal ligament is portal stasis with resultant intestinal congestion which may cause adverse effects on the intestinal functions. CD44 is a transmembrane glycoprotein present in many types of epithelial cells. By mediating the attachment of dividing crypt cells to the basal lamina via hyaluronan, CD44 is considered to play a role in maintaining the intestinal villus integrity. Apoptosis is a pathway of cell death orchestrated by a family of proteases called caspases. ZVAD-fmk is a cell-permeable irreversible inhibitor of caspase and might block the processing of many caspases. This study is designed with the purpose to evaluate the impact of intraoperative occlusion of the hepatoduodenal ligament on hepatocyte and intestine functions and also to evaluate the potential influence of ZVAD-fmk on the hepatocyte and intestine functions.

MATERIALS AND METHODS

Male Sprague-Dawley rats were randomized to 5 groups. Group 1(C) underwent sham operation. Group 2 (HDL30) underwent occluding the hepatoduodenal ligament by for 30 minutes. Group 3 (HDL 15) underwent occluding the hepatoduodenal ligament by for 15 minutes, releasing for 5 minutes, underwent occlusion for another 15 minutes. Group 4 (ZHDL30) first received ZVAD-fmk, then underwent occluding the hepatoduodenal ligament by for 30 minutes. Group 5 (ZHDL15) first received ZVAD-fmk, then underwent occluding the hepatoduodenal ligament for 15 minutes, releasing for 5 minutes, underwent occlusion for another 15 minutes. After removing the temporary occlusion, liver tissue and proximal jejunum were harvested. Hepatocyte and intestine apoptosis were quantitated using the TUNEL method. CD 44 status of jejunum were determined by immunohistochemical staining.

RESULTS

Hepatocyte apoptosis was significantly increased in group (HDL30) and group (HDL15) when compared with group (C). ZVAD-fmk effectively attenuated this phenomenon in both groups. There was no significant difference between group (HDL30) and group (HDL15). Jejunal apoptosis was significantly increased in group (HDL30) and group (HDL15) when compared with group (C). ZVAD-fmk effectively attenuated this phenomenon in both groups. There was no significant difference between group (HDL30) and group (HDL15). CD44 expression on jejunum was significantly increased in group (HDL30) and group (HDL15) when compared with group (C). ZVAD-fmk failed to effectively diminish this phenomenon.

CONCLUSION

Occlusion of the hepatoduodenal ligament significantly increased both hepatocyte and jejunal apoptosis and pretreatment with ZVAD-fmk could effectively diminish such phenomenon. CD44 expression on jejunum was also significantly increased by intraoperative occlusion of the hepatoduodenal ligament, yet pretreatment with ZVAD-fmk failed to show significant effect on such phenomenon.