[The influence of dietary regimen on the stimulation of microsomal monooxygenases in rat liver induced by 2,3-dimethylquinoxaline].

Activities, on the hepatic microsomal fraction, of the following enzymes: aniline aromatic hydroxylase, p-nitroanisole O-demethylase, aminopyrine N-demethylase, N-methylaniline N-demethylases, as well as the P-450 cytochrome level, have been evaluated on female rats. During a period of 26 days, they are fed on 4 diets including either: 20% or 30% proteins, or: 1% or 30% lipids. A parallel study is carried out: animals fed on the same diets are given, orally on the 22nd day and for 4 days, a bactericide, the dimethyl-2.3 quinoxaline; the dose is 500 mg/kg/day, with an interval of 24 hours. 1) A stimulation of the microsomal monooxygenase activity and an increase in the P-450 cytochrome level are induced by the dimethyl-2.3 quinoxaline on all animals regardless the diet they are on. 2) The hyperlipidic diet is the only one to induce an increased activity of the same enzymes, but the P-450 cytochrome level remains unchanged. 3) In rats fed on the hyperlipidic diet and treated with dimethyl-2.3 quinoxaline, the effects of this substance and of this diet, on the drug-metabolizing enzymes, become additive.