van Jaarsveld H, Pool G F, Barnard H C
Department of Chemical Pathology, University of the Orange Free State/Universitas Hospital, Bloemfontein, Republic of South Africa.
Res Commun Mol Pathol Pharmacol. 1998 Jan;99(1):69-80.
Low-density lipoprotein (LDL) cholesterol participates in the atherosclerotic process only after oxidative modification (o-LDL). Persons with elevated body iron concentrations are at higher risk of atherosclerosis. Iron in vitro is capable of oxidizing LDL, but it is unknown whether or not high dietary iron concentrations alter LDL in vivo. The aim of this study was, therefore, to investigate (i) whether dietary iron concentrations cause LDL-cholesterol oxidation and (ii) whether antioxidants can prevent such changes. Rats received diets differing only in iron concentration: 35 mg/kg, 150 mg/kg or 300 mg/kg diet. A LDL-VLDL particle was isolated and the following parameters measured: malondialdehyde and lipid hydroperoxide concentrations (as an indication for lipid peroxidation); alpha-tocopherol and retinol concentrations (as antioxidants); protein sulfhydryl and carbonyl concentrations (as an indication of protein modification); agarose gel electrophoresis and cholesterol/protein ratio. Dietary iron increased LDL-VLDL lipid peroxidation (malondialdehyde and lipid hydroperoxide concentrations), protein modification (sulfhydryl concentration), agarose migration distance and band width as well as cholesterol/protein ratio. Increased quantities of dietary iron led to a higher degree of oxidative change in LDL-VLDL. Lipid peroxidation, as well as protein modification, occurred, suggesting apoB changes. This was probably due to diminished antioxidant concentrations of alpha-tocopherol and beta-carotene. Antioxidant supplementation (alpha-tocopherol and beta-carotene), however, prevented all the above changes and could be helpful in the prevention of atherosclerosis.
低密度脂蛋白（LDL）胆固醇只有在发生氧化修饰（氧化型LDL，o-LDL）后才会参与动脉粥样硬化过程。体内铁浓度升高的人患动脉粥样硬化的风险更高。体外实验表明铁能够氧化LDL，但高膳食铁浓度是否会在体内改变LDL尚不清楚。因此，本研究的目的是调查：（i）膳食铁浓度是否会导致LDL胆固醇氧化；（ii）抗氧化剂是否能预防此类变化。给大鼠喂食仅铁浓度不同的饲料：35毫克/千克、150毫克/千克或300毫克/千克饲料。分离出LDL-VLDL颗粒并测量以下参数：丙二醛和脂质氢过氧化物浓度（作为脂质过氧化的指标）；α-生育酚和视黄醇浓度（作为抗氧化剂）；蛋白质巯基和羰基浓度（作为蛋白质修饰的指标）；琼脂糖凝胶电泳和胆固醇/蛋白质比率。膳食铁增加了LDL-VLDL的脂质过氧化（丙二醛和脂质氢过氧化物浓度）、蛋白质修饰（巯基浓度）、琼脂糖迁移距离和条带宽度以及胆固醇/蛋白质比率。膳食铁含量增加导致LDL-VLDL的氧化变化程度更高。发生了脂质过氧化以及蛋白质修饰，提示载脂蛋白B发生了变化。这可能是由于α-生育酚和β-胡萝卜素等抗氧化剂浓度降低所致。然而，补充抗氧化剂（α-生育酚和β-胡萝卜素）可预防上述所有变化，可能有助于预防动脉粥样硬化。
