Table of Contents Author Guidelines Submit a Manuscript
Journal of Lipids
Volume 2011 (2011), Article ID 101242, 9 pages
http://dx.doi.org/10.1155/2011/101242
Research Article

Mechanism of Resistance to Dietary Cholesterol

1Department of Pathology, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
2Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612, USA

Received 25 May 2011; Revised 27 July 2011; Accepted 28 July 2011

Academic Editor: Akihiro Inazu

Copyright © 2011 Lindsey R. Boone et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. Alterations in expression of hepatic genes that could contribute to resistance to dietary cholesterol were investigated in Sprague-Dawley rats, which are known to be resistant to the serum cholesterol raising action of dietary cholesterol. Methods. Microarray analysis was used to provide a comprehensive analysis of changes in hepatic gene expression in rats in response to dietary cholesterol. Changes were confirmed by RT-PCR analysis. Western blotting was employed to measure changes in hepatic cholesterol 7α hydroxylase protein. Results. Of the 28,000 genes examined using the Affymetrix rat microarray, relatively few were significantly altered. As expected, decreases were observed for several genes that encode enzymes of the cholesterol biosynthetic pathway. The largest decreases were seen for squalene epoxidase and lanosterol 14α demethylase (CYP 51A1). These changes were confirmed by quantitative RT-PCR. LDL receptor expression was not altered by dietary cholesterol. Critically, the expression of cholesterol 7α hydroxylase, which catalyzes the rate-limiting step in bile acid synthesis, was increased over 4-fold in livers of rats fed diets containing 1% cholesterol. In contrast, mice, which are not resistant to dietary cholesterol, exhibited lower hepatic cholesterol 7α hydroxylase (CYP7A1) protein levels, which were not increased in response to diets containing 2% cholesterol.