Accumulation of hydrophobic bile acids during cholestasis leads to generation of oxygen free radicals in the liver. Accordingly, this study investigated whether polyphenols from green tea Camellia sinenesis, which are potent free radical scavengers, decrease hepatic injury caused by experimental cholestasis. Rats were fed a standard chow or a diet containing 0.1% polyphenolic extracts from C. sinenesis starting 3 days before bile duct ligation. After bile duct ligation, serum alanine transaminase increased to 760 U/l after 1 day in rats fed a control diet. Focal necrosis and bile duct proliferation were also observed after 1–2 days, and fibrosis developed 2–3 wk after bile duct ligation. Additionally, procollagen-α1(I) mRNA increased 30-fold 3 wk after bile duct ligation, accompanied by increased expression of α-smooth muscle actin and transforming growth factor-β and the accumulation of 4-hydroxynenonal, an end product of lipid peroxidation. Polyphenol feeding blocked or blunted all of these bile duct ligation-dependent changes by 45–73%. Together, the results indicate that cholestasis due to bile duct ligation causes liver injury by mechanisms involving oxidative stress. Polyphenols from C. sinenesis scavenge oxygen radicals and prevent activation of stellate cells, thereby minimizing liver fibrosis.
Dissociation of bile flow and biliary lipid secretion from biliary lysosomal enzyme output in experimental cholestasis.
