Effect of dietary substitution of sucrose and its constituent monosaccharides on the activity of aromatic hydroxylase and the level of cytochrome P-450 in hepatic microsomes of growing rats

The effect of dietary substitution of starch by sucrose, glucose, fructose or an equimolar mixture of glucose and fructose on the activity of biphenyl hydroxylase and the level of the major terminal mixed function oxygenase, cytochrome P-450, has been studied in hepatic microsomal preparations from growing rats. The substitution of sucrose for starch depressed the concentration and total activity per liver of biphenyl 4-hydroxylase and the concentration, but not the total amount, of cytochrome P-450 in weanling rats. The absolute amount of these enzymes in whole liver was not, however, similarly depressed by the constituents of sucrose, namely glucose and fructose, either when given alone or in equimolar mixture. All these sugars, however, depressed the total activity of biphenyl 2-hydroxylase. The activity of biphenyl 4-hydroxylase in the liver of weanling rats, but not of adults, was reduced when the level of sucrose in the diet was reduced from 60 to 10 %.