Measurement of hepatic sterol synthesis in the Mongolian gerbil in vivo using [3H]water: diurnal variation and effect of type of dietary fat.
Measurement of hepatic sterol synthesis in the Mongolian gerbil in vivo using [3H]water: diurnal variation and effect of type of dietary fat.
复制标题
使用[3H]水测量蒙古沙鼠体内肝脏甾醇合成：昼夜变化和膳食脂肪类型的影响。
作者：
N. J. Mercer;B. Holub
通过监测毛地黄皂苷可沉淀甾醇的放射性掺入，在体内测定了给予[3 H]水后雄性长爪沙鼠（Meriones unguiculatus）的甾醇肝脏合成。在自由采食的条件下，交替12小时的光照（0200至1400小时）和黑暗（1400至0200小时），胆固醇合成呈现昼夜节律。天顶在1500和2100小时之间到达，最低点在大约10-12小时后的0200和0400小时之间到达，这提供了9.6到1.0的天顶/最低点比。在沙鼠体内的肝甾醇合成率和血浆胆固醇水平进行了测定，喂食半纯化的饮食含有19.5%牛油+0.5%红花，20%猪油，或20%红花油和广泛不同比例的多不饱和：饱和脂肪酸。所有日粮均含有0.01%的胆固醇和0.05%的植物甾醇。实验饮食3天后，平均胆固醇合成率（nmol/g肝脏/小时）分别为41.5，26.6和13.8的动物喂养的饮食含有牛脂，猪油，红花油，分别。7天和14天后，喂食红花油的沙鼠合成率最低，血浆胆固醇水平也最低。这些结果表明，饲料脂质的类型可以显着影响在体内沙鼠肝脏甾醇的生物合成速率。这种反应可能至少部分导致观察到的血浆胆固醇水平差异。
The hepatic synthesis of sterol was measured in the male Mongolian gerbil (Meriones unguiculatus) in vivo following the administration of [3H]water by monitoring the incorporation of radioactivity into digitonin-precipitable sterol. A diurnal rhythm in cholesterol synthesis was exhibited under conditions of ad libitum feeding with alternating 12-hour periods of light (0200 to 1400 hr) and dark (1400 to 0200 hr). The zenith was reached between 1500 and 2100 hr and the nadir approximately 10-12 hours later between 0200 and 0400 hr, which provided a zenith/nadir ratio of 9.6 to 1.0. The in vivo rates of hepatic sterol synthesis and plasma cholesterol levels were measured in gerbils fed semi-purified diets containing either 19.5% beef tallow + 0.5% safflower, 20% lard, or 20% safflower oil and widely differing ratios of polyunsaturated: saturated fatty acids. All diets were equalized to contain 0.01% cholesterol and 0.05% plant sterol. After 3 days on the experimental diets, the mean rates of cholesterol synthesis (nmol/g liver per hr) were 41.5, 26.6, and 13.8 for animals fed the diets containing beef tallow, lard, and safflower oil, respectively. After 7 and 14 days, synthetic rates were lowest in the gerbils fed safflower oil as were also the plasma cholesterol levels. These results indicate that the type of dietary lipid can significantly influence the in vivo rate of sterol biosynthesis in gerbil liver. This response may contribute, at least in part, to the observed differences in plasma cholesterol levels.