Epigallocatechin gallate enhances biliary cholesterol secretion in healthy rats and lowers plasma and liver cholesterol in ethinylestradiol-treated rats
Abstract
The present paper describes our investigation of the effect of epigallocatechin-gallate (EGCG), the major active ingredient from the green tea, on liver cholesterol metabolism in control and ethinylestradiol-treated rats. The results demonstrated that EGCG administration to control rats did not change plasma total cholesterol, but reduced VLDL cholesterol.
However, EGCG markedly enhanced biliary cholesterol and phospholipid secretion, despite the decrease in bile flow and biliary bile acid secretion. In ethinylestradiol treated rats, EGCG caused reduction in hepatic cholesterol accumulation and consequently also mitigation of drug-induced hepatomegaly.
These effect of EGCG were attributable to its inducing effect on protein expression of ATP-binding cassette transporter G5 and 8 (ABCG5/8) - i.e. cholesterol biliary exporter, and the reduced expression of acyl-CoA:cholesterol acyltransferase (ACAT2) protein - i.e. limiting step for cholesterol liver storage and VLDL production. Our data for the first time demonstrated these metabolic effect for such a commonly used substance.