Hannah J S, Yamane K, Kataoka S, Anthony M, Howard B V
Medlantic Research Institute, Washington, DC 20010, USA.
Atherosclerosis. 1997 Jul 11;132(1):19-27. doi: 10.1016/s0021-9150(97)00070-1.
The purpose of this study was to examine the effects of various dietary fats on low density lipoprotein (LDL) binding in an in vitro system where receptor number is not regulated. Cynomolgus monkeys were fed diets containing 37% of energy from fat, with various degrees of saturation, and 0.4 mg/kcal cholesterol or low-fat (13% of energy), low cholesterol (0.03 mg/kcal) chow. Plasma LDL was isolated after 16 weeks. The fatty acid composition of LDL showed enrichment corresponding to the dietary fats consumed, and the high fat, high cholesterol diets produced marked hypercholesterolemia compared to chow feeding. Of those fed the high fat diets, monkeys fed the fish oil diet had the highest LDL cholesterol concentrations, 13.25 +/- 0.77 mmol/l, while those fed the safflower oil diet had the lowest, 7.51 +/- 3.31. LDL from chow fed monkeys had the lowest binding affinity; the Kd was 26.2 +/- 8.7 microg/ml, nearly twice that of the high fat diets (P = 0.003). No significant differences in binding were found between the different high fat diets, although there was a trend toward lower affinity in the diets enriched in polyunsaturated fat. LDL size was affected by diet with chow fed monkeys having the smallest average LDL, 259.3 +/- 1.7 A compared to the other groups (P = 0.03). Monkeys fed the fish oil diet tended to have smaller LDL, but this was not significantly different from the other high fat diets. Binding affinity was correlated with LDL size, r = 0.54, P < 0.01. LDL composition, as measured by apo B/cholesterol ratio, was altered by feeding a high fat, high cholesterol diet. The ratio was reduced in the LDL samples from monkeys fed the high fat diets compared to those fed chow, but this ratio was not significantly correlated with binding. Thus, it appears that increasing dietary fat and cholesterol intake increases LDL size and binding affinity, such that LDL metabolism may be altered independently from effects on receptor number; the type of dietary fat does not seem to influence this process when fat and cholesterol content is very high.
本研究的目的是在一个受体数量不受调控的体外系统中，检测各种膳食脂肪对低密度脂蛋白（LDL）结合的影响。将食蟹猴喂以脂肪供能占37%、饱和度不同且胆固醇含量为0.4mg/kcal的膳食，或低脂（供能占13%）、低胆固醇（0.03mg/kcal）的食物。16周后分离血浆LDL。LDL的脂肪酸组成显示出与所摄入膳食脂肪相对应的富集，与喂食普通食物相比，高脂、高胆固醇膳食导致显著的高胆固醇血症。在那些喂食高脂膳食的猴子中，喂食鱼油膳食的猴子LDL胆固醇浓度最高，为13.25±0.77mmol/l，而喂食红花油膳食的猴子LDL胆固醇浓度最低，为7.51±3.31。喂食普通食物的猴子的LDL结合亲和力最低；解离常数（Kd）为26.2±8.7μg/ml，几乎是高脂膳食的两倍（P=0.003）。尽管富含多不饱和脂肪的膳食有亲和力较低的趋势，但不同高脂膳食之间在结合方面未发现显著差异。LDL大小受膳食影响，喂食普通食物的猴子平均LDL最小，为259.3±1.7 Å，与其他组相比有差异（P=0.03）。喂食鱼油膳食的猴子的LDL往往较小，但与其他高脂膳食相比无显著差异。结合亲和力与LDL大小相关，r=0.54，P<0.01。通过载脂蛋白B/胆固醇比值测定的LDL组成因喂食高脂、高胆固醇膳食而改变。与喂食普通食物的猴子相比，喂食高脂膳食的猴子的LDL样本中该比值降低，但该比值与结合无显著相关性。因此，似乎增加膳食脂肪和胆固醇摄入量会增加LDL大小和结合亲和力，从而使LDL代谢可能独立于对受体数量的影响而改变；当脂肪和胆固醇含量非常高时，膳食脂肪的类型似乎不影响这一过程。
