Park J, Lemieux S, Lewis G F, Kuksis A, Steiner G
WHO Collaborating Center for the Study of Atherosclerosis in Diabetes and the Department of Medicine, The Toronto Hospital (General Division), University of Toronto, Ontario, Canada.
J Lipid Res. 1997 Dec;38(12):2529-36.
We have investigated hepatic de novo lipogenesis and the ratio of apoB-48/apoB-100 during chronic carbohydrate supplementation with or without administration of exogenous insulin in rats. Two groups received chronic (2 weeks) carbohydrate supplementation either as 10% glucose or 10% fructose (wt/v) in their drinking water. Two other groups received exogenous insulin chronically, in addition to the monosaccharides above. The insulin was given for 2 weeks as daily human ultralente insulin injections in increasing doses up to 6 units per day. A fifth group of rats (normal control) received only chow and water. The fractional synthetic rate (FSR), the fraction of very low density lipoprotein triglyceride (VLDL-TG) palmitate that was newly made during an 8-h infusion with sodium [1-13C]acetate, was evaluated. The glucose and fructose groups had a 4-fold (0.60%/h) and 7.5-fold (1.13%/h) increase in FSR from baseline, respectively, compared to chow-fed controls (0.15%/h). Chronic exogenous insulin administration resulted in a 11.5 (1.73%/h) and 11.0 (1.65%/h)-fold increase over baseline in the synthesis of newly made VLDL-TG palmitate in the glucose and fructose groups, respectively. The ratio of apoB-48/apoB-100, i.e. apoB-48 enrichment, in VLDL was positively correlated with insulin levels (r = 0.41, P < 0.01) and with FSR (r = 0.39, P < 0.01). The present study shows that carbohydrate supplementation significantly increases the FSR of newly made VLDL-TG palmitate and that this increase is further augmented by chronic hyperinsulinemia.
我们研究了在大鼠长期补充碳水化合物期间，给予或不给予外源性胰岛素时肝脏从头脂肪生成及载脂蛋白B-48/载脂蛋白B-100的比例。两组大鼠在饮用水中接受为期2周的长期碳水化合物补充，分别为10%葡萄糖或10%果糖（重量/体积）。另外两组除上述单糖外，还长期接受外源性胰岛素。胰岛素连续注射2周，每天给予人超长效胰岛素，剂量逐渐增加至每天6单位。第五组大鼠（正常对照组）仅给予饲料和水。评估了分数合成率（FSR），即在8小时输注[1-13C]醋酸钠期间新生成的极低密度脂蛋白甘油三酯（VLDL-TG）棕榈酸酯的比例。与喂食饲料的对照组（0.15%/小时）相比，葡萄糖组和果糖组的FSR分别比基线增加了4倍（0.60%/小时）和7.5倍（1.13%/小时）。长期给予外源性胰岛素导致葡萄糖组和果糖组新生成的VLDL-TG棕榈酸酯合成分别比基线增加11.5倍（1.73%/小时）和11.0倍（1.65%/小时）。VLDL中载脂蛋白B-48/载脂蛋白B-100的比例，即载脂蛋白B-48富集，与胰岛素水平呈正相关（r = 0.41，P < 0.01），与FSR也呈正相关（r = 0.39，P < 0.01）。本研究表明，补充碳水化合物显著增加了新生成的VLDL-TG棕榈酸酯的FSR，并且这种增加会因慢性高胰岛素血症而进一步增强。
