Role of dietary corn oil in the function of hepatic drug and carcinogen metabolizing enzymes of starved-refed rats: response to the mixed function oxidase inducer, 3-methylcholanthrene.
Hepatic microsomes from rats starved 48 hours and refed diets containing zero, 3 or 20% corn oil metabolized benzo(a)pyrene, aniline and N-nitrosodimethylamine in proportion to the quantity of corn oil in the diet. No diet-related changes in apparent Km for these reactions were evident. The content of microsomal cytochrome P-450 was also clearly dependent upon the content of corn oil in the refed diets. When metabolism of these three substrates is expressed as product formed per unit of cytochrome P-450, the activities are least in microsomes from rats fed the 20% corn oil diet, suggesting that P-450 species responsible for metabolizing substrates other than these are enhanced preferentially. Cytosolic glutathione S-transferase activities are also increased with increasing corn oil in the diet. The administration of 3-MC increased cytochrome P-448 content of microsomes from all rats, regardless of diet, however highest content was present in microsomes from rats fed the 20% corn oil diet. Induction of benzo(a)pyrene hydroxylase was not influenced by dietary corn oil and, as anticipated, 3-MC caused significant repression of DMN N-demethylase in microsomes from rats fed the 20% corn oil diet. In like manner, 3-MC induced glutathione S-transferase only in cytosol from rats fed the fat-free diet.
D000818:Animals; D002273:Carcinogens / Q000378:metabolism*; D003314:Corn Oil / Q000008:administration & dosage*; D019388:Cytochrome P-450 CYP1A2; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis; D003580:Cytochromes / Q000096:biosynthesis; D004041:Dietary Fats / Q000008:administration & dosage*; D004790:Enzyme Induction / Q000187:drug effects; D007700:Kinetics; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000096:biosynthesis*; D010938:Plant Oils / Q000008:administration & dosage*; D051381:Rats; D011919:Rats, Inbred Strains
D002273:Carcinogens; D003580:Cytochromes; D004041:Dietary Fats; D010938:Plant Oils; D008748:Methylcholanthrene; D003314:Corn Oil; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C017170:Cyp1a2 protein, rat; D019388:Cytochrome P-450 CYP1A2