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Type: Journal article
Title: A Green Tea Catechin Extract Upregulates the Hepatic Low-Density Lipoprotein Receptor in Rats
Author: Bursill, Christina Anne
Roach, Paul D.
Citation: Lipids, 2007; 42 (7):621-627
Publisher: Amer Oil Chemists Soc A O C S Press
Issue Date: 2007
ISSN: 0024-4201
School/Discipline: School of Earth and Environmental Sciences
Abstract: Green tea extracts have hypocholesterolaemic properties in epidemiological and animal intervention studies. Upregulation of the low-density lipoprotein (LDL) receptor may be one mechanism to explain this as it is the main way cholesterol is removed from the circulation. This study aimed to determine if a green tea extract could upregulate the hepatic LDL receptor in vivo in the rat. A green tea extract (GTE) enriched in its anti-oxidant constituents, the catechins, was fed to rats (n = 6) at concentrations of either 0, 0.5, 1.0 or 2.0% (w/w) mixed in with their normal chow along with 0.25% (w/w) cholesterol for 12 days. Administration of the GTE had no effect on plasma total or LDL cholesterol concentrations but high-density lipoprotein significantly increased (41%; p < 0.05). Interestingly, there was a significant increase in LDL receptor binding activity (2.7-fold) and LDL receptor protein (3.4-fold) in the 2% (w/w) treatment group compared to controls. There were also significant reductions in liver total and unesterified cholesterol (40%). Administration of the GTE significantly reduced cholesterol absorption (24%) but did not affect cholesterol synthesis. These results show that, despite no effect on plasma cholesterol, the GTE upregulated the LDL receptor in vivo. This appears to be via a reduction in liver cholesterol concentration and suggests that the green tea extract was able to increase the efflux of cholesterol from liver cells.
Keywords: Green tea; LDL receptor; Cholesterol synthesis; Cholesterol absorption; Lathosterol; Phytosterols
DOI: 10.1007/s11745-007-3077-x
Appears in Collections:Earth and Environmental Sciences publications

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