The Tohoku Journal of Experimental Medicine
Online ISSN : 1349-3329
Print ISSN : 0040-8727
ISSN-L : 0040-8727
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Clofibrate, a Peroxisome-Proliferator, Enhances Reverse Cholesterol Transport Through Cytochrome P450 Activation and Oxysterol Generation
Jing-Zhi GuanNaoki TamasawaHiroshi MurakamiJun MatsuiKazumi YamatoToshihiro Suda
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2003 Volume 201 Issue 4 Pages 251-259

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Abstract

Fibrates are widely used hypolipidemic agents that activate the peroxisome proliferator-activated receptor α (PPARα) and regulate the expression of many genes involved in lipid metabolism. We studied the mechanism of the effect of clofibrate on cholesterol homeostasis. Rats were fed with chow containing clofibrate, cytochrome P-450 inhibitor ketoconazole, or clofibrate plus ketoconazole. Control rats were fed only with normal chow. The levels of six oxysterols in liver microsome were determined. The levels of mRNAs for liver X receptor alpha (LXRα), ATP-binding cassette A1 (ABCA1), PPARα and cholesterol 7α-hydroxylase (CYP7A) in the liver were analyzed by northern blotting. Clofibrate administration decreased plasma levels of total cholesterol and triglyceride and increased high-density lipoprotein-cholesterol (HDL-C). Clofibrate increased the levels of liver microsomal oxysterols including 25- and 27-hydroxycholesterol, which are potent activators of LXRα. Clofibrate also enhanced the expression of mRNAs for PPARα, LXRα, and ABCA1. Simultaneous administration of ketoconazole suppressed the effects of clofibrate on plasma lipids, hepatic oxysterol levels, and the expression of the genes. Clofibrate increases cytochrome P450 content and the resulting oxysterol generation may partly mediate the clofibrate-induced up-regulattion of LXRα and ABCA1, which are related to reverse cholesterol transport.

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© 2003 Tohoku University Medical Press
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