Rate of alteration of hepatic mixed-function oxidase system in rats fed different dietary fats.

Studies were carried out to evaluate and relate the rate of alteration in mixed-function oxidase system with the changes of the fatty acid composition of rat microsomes induced by different dietary lipids. Male weanling rats were fed from day 21 to 120 with a commercial rat diet or a semisynthetic diet containing no fat or 10% fat consisting of peanut-rapeseed oil, sunflower oil, or salmon oil. In rats fed a fat-free diet, the cytochrome P-450 concentration and aniline hydroxylase, aminopyrine N-demethylase, and NADPH-cytochrome-c reductase activities of liver microsomes at 120 days were, respectively, 26, 16, 10, and 24% lesser than those of rats fed the control diet. However, cytochrome b5 concentration and NADH-cytochrome-b5 reductase activity were, respectively, 33 and 43% higher than those of the control group at the same time. When rats were fed the sunflower oil diet, the cytochrome P-450 concentration and NADH-cytochrome-b5 reductase activity at 120 days were, respectively, 11 and 23% lesser than those of control group. But the cytochrome b5 concentration was 10% higher than that of the control group. In rats fed the fish oil diet, the cytochrome P-450 concentration and NADPH-cytochrome-c reductase, aniline hydroxylase, and aminopyrine N-demethylase activities at 120 days were, respectively, 30, 48, 41, and 31% higher than those of rats fed the control diet. These enzymes were correlated very well (0.84 < r < 0.93), P < 0.05 with dietary sigma polyunsaturated fatty acids (n-3).(ABSTRACT TRUNCATED AT 250 WORDS)