Roles of protein kinase C and fructose in hepatic injury caused by obstructive jaundice

Abstract

The regulating mechanism in hepatic injury caused by obstructive jaundice (OJ) was examined in this study. Rat hepatocytes were harvested by in situ collagenase perfusion and subjected to primary culture. The heptocytes were pre-treated with various concentrations of protein kinase C (PKC) agonist PMA and its inhibitor chelerythrine and cultured for 20 min. After the treatment, 50 micromol/L glycochenodeoxycholate (GCDC) was added and the cells were cultured for an additional 24 h. Cells were then detected by flow cytometry (FCM) and TUNEL. After hepatocytes were treated with different concentrations of fructose and 100 microM GCDC, the cells were examined by FCM and TUNEL. Experimental obstructive jaundice (BDL) was induced by double ligation of the bile duct. After BDL, the rats were fed with or without fructos and sacrificed 3, 7, 14 and 21 days after the ligation. The apoptotic status was observed in liver of all rats with TUNEL and PKC protein in liver of OJ was studied by immunohistochemical method. Our results showed that PMA increased GCDC-induced apoptosis and chelerythrine decreased GCDC-induced apoptosis in a concentration-dependent manner. After the treatment with fructose of different concentrations, 100 microM GCDC decreased the apoptotic rate and the apoptotic rate decreased with the increase of fructose concentration. The apoptotic rate of liver was related to the time of OJ. Without the treatment of fructose, PKC and apoptosis index (AI) were highest 14 days after the bile duct ligation. With the treatment of fructose, apoptosis index (AI) and PKC were decreased from the 14th day after the bile duct ligation. It is concluded that PKC is involved in the regulation of apoptosis in the liver cells with OJ and plays important roles in the development and progression of liver injury caused by OJ. Fructose can protect hepatocytes in the bile salt-induced apoptosis by regulating PKC.