| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2004: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
The effects of dietary fat and protein on the ovarian hormone deficiency-associated increase in plasma cholesterol concentration were studied in ovariectomized 6-month-old female rats. Oleic acid-rich safflower oil, linoleic acid-rich safflower oil, perilla oil, fish oil, hydrogenated palm oil, milk fat were used as dietary fat source. Casein, rice protein, soybean protein, potato protein, wheat protein and cod protein were used as dietary protein source. Ovariectomized rats were fed the diets based on AIN93G containing each test fat or protein for 28 days.
The plasma cholesterol concentration of the fish oil group was significantly lower than those of other groups, and that of the perilla oil group was a tendency lower than those of other groups. α-linoelenic acid is changed into EPA and DHA in a body, which suggests that the plasma cholesterol concentration lowering effect of fish and perilla oil might depend on EPA and DHA. The level of LDL-receptor mRNA was a tendency lower in fish
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oil and perilla oil groups than in other groups. The level of CYP7A1 mRNA was not affected by dietary fat source. The fecal excretion of bile acid was higher in fish oil, hydrogenated palm oil and milk fat groups than in other groups. However, the increased fecal excretion of bile acid did not necessarily lead to the reduction of plasma cholesterol.
The plasma cholesterol concentrations of potato protein, soybean protein and cod protein groups were significantly lower than that of casein group, but those of rice protein and wheat protein were not. I has been suggested that the higher plasma cholesterol concentration of casein might depend on the higher methionine contnt, lysine/arginine ratio and methionine/glycine ratio compared other dietary protein. The content of methionine was lower in wheat protein, rice protein, soybean protein and potato protein than that in casein, however was not significant difference between wheat protein, rice protein, soybean protein and potato protein. The content of methionine, lysine/arginine ratio and methionine/glycine ratio of cod protein was lower than those of casein. The levels of LDL-receptor mRNA and CYP7A1 were not affected by dietary protein. It was clarified that the plasma cholesterol concentration was affected by the quality of the protein, but a further examination is necessary on the relation to the amino acid composition and hypocholesterolemic effect of dietary protein. Less
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