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Regulatory Mechanism of Plasma Cholesterol Concentration by Dietary Protein : Evidence that plasma cholesterol is not regulated by modification of entero-hepatic circulation of steroids.

膳食蛋白质对血浆胆固醇浓度的调节机制：证据表明血浆胆固醇不受类固醇肠肝循环改变的调节。

基本信息

批准号：
63480053
负责人：
KIRIYAMA Shuhachi
金额：
$ 3.2万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

We carried out a series of experiments to elucidate the possible mechanism by which dietary soybean protein isolate (SPI) produced a reduction of plasma cholesterol concentration compared with dietary casein in rats fed a cholesterol-bile acid-free diet. Within 3 days after the diet crossover, plasma cholesterol concentration in each group of intact rats reached rapidly the same level as that in its previous counterpart. The inherent responses of plasma cholesterol concentration to casein and13EA\ : SPI were not changed by the resection of the jejunum or the ileum and the administration of cholestyramine or beta-sitosterol. The rates of cholesterol biosynthesis in vivo (in liver and small intesine) were significantly higher in SPI-fed rats tha13EA\ : n in casein-fed rats.The hypocholesterolemic effect of SPI disappeared when methionine (Met) was supplemented at a level equivalent to casein. The effects of casein and SPI were reproduced by their equivalent amino acid mixtures. The ratio of Met/glycine (Gly) in postpr13EA\ : andial portal blood was significantly higher when casein or casein-simulated amino acids mixture was fed than when SPI or SPI-simulated amino acid mixture was fed. The casein-induced increase in the level of plasma cholesterol concentration was attr13EA\ : ibuted to an increase in high density lipoprotein (HDL) cholesterol. HDL-cholesterol concentration showed a positive correlation with the lecithin : cholesterol acyltransferase activity. HDL-apolipoprotein level in aortic blood and synthetic rate of13EA\ : HDL-apolipoproteins in vivo was higher in casein-fed rats than in SPI-fed rats. From all of these observations, we conclude that the dietary protein-induced alterations of the plasma cholesterol concentration would be caused through the change in a13EA\ : polipoproteins composing HDL.

我们进行了一系列实验，以阐明在饲喂不含胆固醇-胆汁酸饮食的大鼠中，大豆分离蛋白（SPI）与酪蛋白相比降低血浆胆固醇浓度的可能机制。在饮食交叉后3天内，各组正常大鼠血浆胆固醇浓度迅速达到与前一组相同的水平。血浆胆固醇浓度对酪蛋白和13ea \: SPI的固有反应不因切除空肠或回肠以及给予胆胺或β -谷甾醇而改变。spi喂养的大鼠体内（肝脏和小肠）胆固醇的生物合成率显著高于酪蛋白喂养的大鼠。当蛋氨酸（Met）添加到与酪蛋白相当的水平时，SPI的降胆固醇作用消失。酪蛋白和SPI的作用可通过它们的等效氨基酸混合物再现。饲喂酪蛋白或酪蛋白模拟氨基酸混合物的大鼠门脉血中蛋氨酸/甘氨酸（Gly）比饲喂SPI或SPI模拟氨基酸混合物的大鼠门脉血中蛋氨酸/甘氨酸（Gly）比饲喂酪蛋白或SPI模拟氨基酸混合物的大鼠门脉血中蛋氨酸/甘氨酸（Gly）比饲喂酪蛋白或SPI模拟氨基酸混合物的大鼠门脉血中蛋氨酸/甘氨酸（Gly）显著升高。高密度脂蛋白胆固醇浓度与卵磷脂-胆固醇酰基转移酶活性呈正相关。酪蛋白喂养的大鼠主动脉血hdl -载脂蛋白水平和体内13ea \: hdl -载脂蛋白合成率高于spi喂养的大鼠。从所有这些观察中，我们得出结论，膳食蛋白质引起的血浆胆固醇浓度的改变可能是通过组成HDL的a13EA\：脂蛋白的改变引起的。