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Diet-Induced Occlusive Coronary Atherosclerosis, Myocardial Infarction, Cardiac Dysfunction, and Premature Death in Scavenger Receptor Class B Type I-Deficient, Hypomorphic Apolipoprotein ER61 Mice

Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Circulation (Impact Factor: 14.95). 07/2005; 111(25):3457-64. DOI: 10.1161/CIRCULATIONAHA.104.523563
Source: PubMed

ABSTRACT Normal chow (low fat)-fed mice deficient in both the HDL receptor SR-BI and apolipoprotein E (SR-BI/apoE dKO) provide a distinctive model of coronary heart disease (CHD). They exhibit early-onset hypercholesterolemia characterized by unesterified cholesterol-rich abnormal lipoproteins (lamellar/vesicular and stacked discoidal particles), occlusive coronary atherosclerosis, spontaneous myocardial infarction, cardiac dysfunction, and premature death ( approximately 6 weeks of age). Mice in which similar features of CHD could be induced with a lipid-rich diet would represent a powerful tool to study CHD.
To generate a diet-inducible model of CHD, we bred SR-BI-deficient (SR-BI KO) mice with hypomorphic apolipoprotein E mice (ApoeR61(h/h)) that express reduced levels of an apoE4-like murine apoE isoform and exhibit diet-induced hypercholesterolemia. When fed a normal chow diet, SR-BI KO/ApoeR61(h/h) mice did not exhibit early-onset atherosclerosis or CHD; the low expression level of the apoE4-like murine apoE was atheroprotective and cardioprotective. However, when fed an atherogenic diet rich in fat, cholesterol, and cholate, they rapidly developed hypercholesterolemia, atherosclerosis, and CHD, a response strikingly similar to that of SR-BI/apoE dKO mice fed a chow diet, and they died 32+/-6 days (50% mortality) after initiation of the high-fat feeding.
The SR-BI KO/ApoeR61(h/h) mouse is a new model of diet-induced occlusive coronary atherosclerosis and CHD (myocardial infarction, cardiac dysfunction and premature death), allowing control of the age of onset, duration, severity, and possibly regression of disease. Thus, SR-BI KO/ApoeR61(h/h) mice have the potential to contribute to our understanding of CHD and its prevention and treatment.

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    • "Hypercholesterolemia diets have been recognized as the major cause of cardiac hypertrophy and are associated with various heart diseases [4] [5] [7] [32]. Our experimental results indicate the significant reduction of the WHW/BW and LVW/BW ratios in hamsters from Li-Fu formula group compared with those from cholesterol group. "
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    • "Reverse cholesterol transport (RCT) driven by SR-BI in the liver, therefore, represents a key pathway for hepatic clearance of HDL cholesterol and prevention of the build-up of cholesterol in inflammatory cells in the artery wall, thereby protecting against atherosclerosis [3] [4]. Studies from gene-targeted mouse models have demonstrated that knocking out SR- BI expression results in impaired hepatic clearance of HDL cholesterol leading to increased amounts of cholesterol in the blood associated with abnormally large HDL particles, as well as reduced levels of cholesterol in bile [5] [6] [7] [8] [9] [10] [11]. On the other hand, overexpression of SR-BI in livers of mice results in increased clearance of HDL cholesterol and is accompanied by reduced levels of cholesterol associated with HDL in blood, and increased levels of cholesterol in bile [12– 14]. "
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