Raman spectroscopic evaluation of the effects of diet and lipid-lowering therapy on atherosclerotic plaque development in mice.

Quantitative characterization of atherosclerotic plaque composition with standard histopathological methods remains limited to sectioned plaques. Raman spectroscopy enables nondestructive quantification of atherosclerotic plaque composition. We used Raman spectroscopy to study the effects of diet and lipid-lowering therapy on plaque development in apolipoprotein (APO) E*3-Leiden transgenic mice. Raman spectra were obtained over the full width and entire length of the ascending aorta and aortic arch. Spectra were modeled to calculate the relative dry weights of cholesterol and calcium salts, and quantitative maps of their distribution were created. In male mice (n=20) that received a high-fat/high-cholesterol (HFC) diet for 0, 2, 4, or 6 months, Raman spectroscopy showed good correlation between cholesterol accumulation and total serum cholesterol exposure (r approximately 0.87, P<0.001). In female mice (n=10) that were assigned to an HFC diet, with or without 0.01% atorvastatin, a strong reduction in cholesterol accumulation (57%) and calcium salts (97%) (P<0.01) was demonstrated in the atorvastatin-treated group. In conclusion, Raman spectroscopy can be used to quantitatively study the size and distribution of depositions of cholesterol and calcification in APOE*3-Leiden transgenic mice. This study encourages Raman spectroscopy for the quantitative investigation of atherosclerosis and lipid-lowering therapy in larger animals or humans in vivo.

Dietary vegetable oil and wood derived plant stanol esters reduce atherosclerotic lesion size and severity in apoE*3-Leiden transgenic mice.

The hypolipidemic and anti-atherosclerotic effects of vegetable oil- and wood-based dietary plant stanol esters were compared in female apoE*3-Leiden transgenic mice at relevant plasma cholesterol levels. The plant stanol esters derived from vegetable oil (sitostanol 65.7%, campestanol 30.1%) had different contents of sitostanol and campestanol than the plant stanol esters derived from wood (sitostanol 87.6%, campestanol 9.5%) or from a mixture of vegetable oil and wood (sitostanol 73.0%, campestanol 24.7%). The mice (10 per group) received for 38 weeks a control diet or diets containing 1.0% (w/w) plant stanol esters derived from either vegetable oil, wood or a mixture of both. Vegetable oil (-46%), wood (-42%) and vegetable oil/wood (-51%) plant stanol esters decreased the plasma cholesterol levels (P<0.0001) by reducing the cholesterol content in plasma very low density-, intermediate density- and to a lesser extent in low density-lipoprotein. Plant stanol ester feeding did not change plasma triglyceride levels. Dietary plant stanol esters reduced the atherosclerotic lesion area by 91+/-13% (vegetable oil), 97+/-4% (wood) and 78+/-34% (vegetable oil/wood) (P<0.0001) and the severity from regular intimal fatty streaks/mild plaques (on average type 2--3 lesions) in controls to individual intimal foam cells (

Dietary plant stanol esters reduce VLDL cholesterol secretion and bile saturation in apolipoprotein E*3-Leiden transgenic mice.

Dietary plant stanols lower serum cholesterol levels in humans and in hyperlipidemic rodents, mainly by inhibition of the intestinal cholesterol absorption. We used female apolipoprotein E*3-Leiden transgenic mice to investigate the consequences of this effect on serum lipid levels and hepatic lipid metabolism. Five groups of 6 or 7 mice received for 9 weeks a diet containing 0.25% cholesterol and 0.0%, 0.25%, 0.5%, 0.75%, or 1.0% (wt/wt) plant stanols (sitostanol 88% [wt/wt], campestanol 10% [wt/wt]) esterified to fatty acids. Compared with the control diet, plant stanol ester treatment dose-dependently reduced serum cholesterol levels by 10% to 33% (P<0.05), mainly in very low density lipoproteins (VLDLs), intermediate density lipoproteins, and low density lipoproteins. Furthermore, 1.0% of the dietary plant stanols significantly decreased the liver contents of cholesteryl esters (-62%), free cholesterol (-31%), and triglycerides (-38%) but did not change the hepatic VLDL-triglyceride and VLDL-apolipoprotein B production rates. However, plant stanol ester feeding significantly decreased the amounts of cholesteryl esters and free cholesterol incorporated in nascent VLDLs by 72% and 30%, respectively, resulting in a net 2-fold decreased VLDL cholesterol output. Liver mRNA levels of low density lipoprotein receptors, 3-hydroxy-3-methylglutaryl coenzyme A synthase, cholesterol 7alpha-hydroxylase, and sterol 27-hydroxylase were not changed by plant stanol ester feeding. Nevertheless, the serum lathosterol-to-cholesterol ratio was significantly increased by 23%, indicating that dietary plant stanol esters increased whole-body cholesterol synthesis. Plant stanol esters also significantly decreased the cholesterol saturation index in bile by 55%. In conclusion, in apolipoprotein E*3-Leiden transgenic mice, plant stanol ester feeding dose-dependently lowered serum cholesterol levels as a result of a reduced secretion of VLDL cholesterol. This was caused by a decreased hepatic cholesterol content that also resulted in a lowered biliary cholesterol output, indicative of a reduced lithogenicity of bile in these mice.