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      Dietary resveratrol increases the expression of hepatic 7α-hydroxylase and ameliorates hypercholesterolemia in high-fat fed C57BL/6J mice

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          Abstract

          Background

          Resveratrol (RSV), a naturally occurring polyphenolic stilbenoid, is known to possess potent anti-atherogenic properties; however, the effect of RSV on hypercholesterolemia is not fully understood. We hypothesized that RSV decreases blood cholesterol levels through the activation of cholesterol 7α-hydroxylase (CYP7A1)-mediated bile acid synthetic pathway pathways in vitro and in vivo.

          Methods

          In this study, we evaluated body weight, serum lipid concentrations, hepatic lipid content and the size of the bile acid pool in high-fat diet (HFD)-fed C57BL/6 J mice that were treated with RSV. In addition, we characterized the underlying mechanism of the effects of RSV in HepG2 hepatocytes by Western blot analysis.

          Results

          RSV (200 mg/kg per day) reduced body weight and liver weight gains, improved serum lipid parameters, reduced hepatic cholesterol accumulation and increased the bile acid pool size in mice fed an HFD for 8 wks. RSV significantly increased liver expression of CYP7A1 mRNA and protein and CYP7A1 enzyme activity. Furthermore, RSV treatment upregulated CYP7A1 expression and induced liver X receptor alpha (LXRα) activation in a time- and dose-dependent manner in HepG2 cells. In addition, the specific liver X receptor alpha (LXRα) inhibitor geranylgeranyl pyrophosphate (GGPP) inhibited the RSV-induced expression of CYP7A1 in HepG2 hepatocytes.

          Conclusion

          The beneficial effects of RSV on HFD-induced hypercholesterolemia are mediated through LXRα signaling pathways, suggesting a potential target for the prevention of dyslipidemia.

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          Most cited references26

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          Chemosensitization of tumors by resveratrol.

          Because tumors develop resistance to chemotherapeutic agents, the cancer research community continues to search for effective chemosensitizers. One promising possibility is to use dietary agents that sensitize tumors to the chemotherapeutics. In this review, we discuss that the use of resveratrol can sensitize tumor cells to chemotherapeutic agents. The tumors shown to be sensitized by resveratrol include lung carcinoma, acute myeloid leukemia, promyelocytic leukemia, multiple myeloma, prostate cancer, oral epidermoid carcinoma, and pancreatic cancer. The chemotherapeutic agents include vincristine, adriamycin, paclitaxel, doxorubicin, cisplatin, gefitinib, 5-fluorouracil, velcade, and gemcitabine. The chemosensitization of tumor cells by resveratrol appears to be mediated through its ability to modulate multiple cell-signaling molecules, including drug transporters, cell survival proteins, cell proliferative proteins, and members of the NF-κB and STAT3 signaling pathways. Interestingly, this nutraceutical has also been reported to suppress apoptosis induced by paclitaxel, vincristine, and daunorubicin in some tumor cells. The potential mechanisms underlying this dual effect are discussed. Overall, studies suggest that resveratrol can be used to sensitize tumors to standard cancer chemotherapeutics. © 2011 New York Academy of Sciences.
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            Variation in susceptibility to atherosclerosis among inbred strains of mice.

            Ten inbred strains of mice were fed an atherogenic diet containing 1.25% cholesterol, 0.5% cholic acid and 15% fat. The strains were examined for plasma cholesterol and triglyceride levels and for formation of lipid-containing lesions in the aortic wall. The strains differed considerably in the frequency of lesion formation after 14 weeks on the atherogenic diet with a range of 0-1.8 lesions/mouse. The order of susceptibility to lesion formation from the least susceptible to the most susceptible was BALB/cJ, C3H/J, A/J, SWR/J, NZB/J, less than 129/J, AKR/J, DBA/2J, less than C57L/J less than C57BL/6J. Total plasma cholesterol after 5 weeks on the diet varied from 131 mg/dl to 328 mg/dl among strains; however, there was little correlation between total cholesterol levels and susceptibility to lesion formation (r = 0.29). Plasma triglycerides after 5 weeks on the diet varied less than cholesterol with a range of 137-220 mg/dl. An analysis of the genetic differences among inbred strains of mice might provide useful insights into lipid metabolism and the development of atherosclerosis.
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              Human cholesterol 7alpha-hydroxylase (CYP7A1) deficiency has a hypercholesterolemic phenotype.

              Bile acid synthesis plays a critical role in the maintenance of mammalian cholesterol homeostasis. The CYP7A1 gene encodes the enzyme cholesterol 7alpha-hydroxylase, which catalyzes the initial step in cholesterol catabolism and bile acid synthesis. We report here a new metabolic disorder presenting with hyperlipidemia caused by a homozygous deletion mutation in CYP7A1. The mutation leads to a frameshift (L413fsX414) that results in loss of the active site and enzyme function. High levels of LDL cholesterol were seen in three homozygous subjects. Analysis of a liver biopsy and stool from one of these subjects revealed double the normal hepatic cholesterol content, a markedly deficient rate of bile acid excretion, and evidence for upregulation of the alternative bile acid pathway. Two male subjects studied had hypertriglyceridemia and premature gallstone disease, and their LDL cholesterol levels were noticeably resistant to 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors. One subject also had premature coronary and peripheral vascular disease. Study of the kindred, which is of English and Celtic background, revealed that individuals heterozygous for the mutation are also hyperlipidemic, indicating that this is a codominant disorder.
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                Author and article information

                Journal
                Lipids Health Dis
                Lipids Health Dis
                Lipids in Health and Disease
                BioMed Central
                1476-511X
                2012
                20 May 2012
                : 11
                : 56
                Affiliations
                [1 ]Department of food science, Guangdong Food and Drug Vocational College, Guangzhou, 510635, China
                Article
                1476-511X-11-56
                10.1186/1476-511X-11-56
                3439360
                22607622
                48d0856a-a33c-443c-abb0-0086c44080c5
                Copyright ©2012 Chen et al.; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 4 April 2012
                : 2 May 2012
                Categories
                Research

                Biochemistry
                high-fat diet,lxrα,resveratrol,mice,bile acid pool size
                Biochemistry
                high-fat diet, lxrα, resveratrol, mice, bile acid pool size

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