[The effect of cholesterol and the nature of dietary fatty acids on the activities of some microsomal monooxygenases in the rat liver].

For 9 weeks, 2-month old male rats were fed diets containing 0 or 2% cholesterol and 15% corn oil or coconut oil (2 x 2 factorial experiment). The activity of several cytochrome P450-dependent monooxygenases from liver microsomes was measured. Dietary cholesterol increased liver weight; this effect was more marked in rats fed unsaturated fat than in those fed saturated fat. The activity of NADPH-cytochrome c reductase and cytochrome b5 contents was also enhanced by dietary cholesterol. The type of dietary fat mainly affected the activities of NADPH-cytochrome c reductase and aminopyrine demethylase. The latter was 34% higher in rats fed corn oil than in rats fed coconut oil. In contrast, the activities of aniline hydroxylase and laurate hydroxylase were not modified by dietary fat. Briefly, the dietary factors studied affected the activity of microsomal monooxygenases differently.