Abstract
The effects of casein and soybean protein on plasma lipoproteins, apoproteins and liver lipids in cholesterol-fed rats were studied.
1) The diet composition for the standard group was (%) : casein 20, corn oil 5, vitamin mix. 1, salt mix. 4, choline chloride 0.2 and corn starch to 100%. The control diet contained 0.5% of cholesterol and 0.3% of sodium cholate and 5% of lard replaced for corn oil.
In rats given a control diet, the concentration of total cholesterol was higher in VLDL and LDL and lower in HDL2, and the concentration of ApoC in VLDL, ApoE, ApoA-1 and ApoC in HDL2 and ApoE in HDL3 were lower than in the animals given a standard diet. On feeding the control diet, much cholesterol and triglyceride were stored in the liver.
2) In order to investigate the effects of qualities and quantities of proteins, the diets containing 5% of lard, 0.5% of cholesterol and 0.125% of sodium cholate was used. The concentrations of serum total cholesterol was 134.7, 108.5, 95.5 and 81.6mg/dl on the diets of casein 20%, casein 40%, soybean protein 20% and soybean protein 40%, respectively. Especially in rats fed soybean protein diets the concentration of triglyceride also decreased.
On the pattern of polyacrylamide gel disc electrophoresis of serum lipoproteins, the percentage of preβ and β fmaction s decreased and that of α3 and α1 increased in rats given a casein 40% diet. Meanwhile that of preβ and β also decreased and α3 and α2 increased in the soybean protein diet groups.
In the casein 40% diet group, ApoC had a tendency to increase.
It was indicated that the biochemical response of lipoproteins was different between casein and soybean protein, and the cholesterol lowering effect was obtained by the feeding of soybean protein and high casein diets.
