Effects of graded levels of dietary casein and corn oil on total cholesterol and triacylglycerol in plasma and liver of rats.

With the intention of examining the effects of dietary protein and oil levels on total cholesterol (T-CHOL) and triacylglycerol (TG) concentrations in the plasma and liver, male Wistar rats, weighing about 170 g, were fed diets containing graded levels of casein and corn oil for 2 wk. At the 5, 20, and 30% levels of dietary corn oil, plasma T-CHOL concentrations were generally enhanced in proportion to the rise of dietary casein level, but plasma TG contents were scarcely influenced by the level. At the 8 to 35% casein levels, plasma T-CHOL and TG concentrations were the highest at the 5% corn oil level, followed in order by the 20 and 30% levels of oil. At the 5 and 20% oil levels, hepatic T-CHOL contents were hardly changed at the 8 to 30% casein levels, but enhanced at the 35% casein level. At the 30% oil level, the T-CHOL contents tended to be changed proportionally to casein levels. At all levels of casein, hepatic T-CHOL contents tended to be relatively high at the 30% corn oil, middle at the 20% oil, and low at the 5% one. At each corn oil level, TG contents in the liver tended to be elevated at the 8 to 15% casein levels and highly preserved at the 15 to 25% ones. Then, the raised TG contents declined at the 5 and 20% levels of corn oil and remained constant at the 30% oil. At each casein level, the contents of hepatic TG were generally high at the 30% oil level, followed in order by the 20 and 5% oil levels. These results indicated that plasma and liver T-CHOL concentrations were proportionately enhnaced by the increase in casein level, and plasma TG contents were hardly affected by the level and hepatic TG ones were lowered by relatively lower or higher casein level, and the rise in corn oil level generally reduced plasma T-CHOL and TG concentrations, but raised hepatic ones.