| Summary: | Effect of epigallocatechin gallate Epigallocatechin gallate (EGCG), the major green tea catechin, has been shown to be protective in various experimental models of liver injury. Since its effect on biliary physiology and liver cholesterol homeostasis has not been thoroughly studied, the present study investigated effect of EGCG on bile flow, bile acid homeostasis and cholesterol metabolism in healthy and ethinylestradiol-treated rats. Compared to controls, EGCG treatment in rats decreased bile flow by 23%. Hepatic paracellular permeability and biliary bile acid excretion were not altered by EGCG administration, but biliary glutathione excretion was reduced by 70%. Accordingly, the main glutathione transporter at the hepatocyte canalicular membrane, multidrug resistance-associated protein 2 (Mrp2), was significantly decreased at the protein level. Interestingly, EGCG markedly enhanced biliary excretion of cholesterol and phospholipids. These changes tightly correlated with increased expression of ATP- binding cassette transporter G5 and G8 (Abcg5/8) and scavenger receptor class B type 1 and with decreased expression of acyl-CoA:cholesterol acyltransferase (Acat2). EGCG administration to rats also doubled plasma bile acid concentrations compared to controls. While protein expression of the main...
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