Tissue specificity of induction of hamster monooxygenase activity by ethanol.
The effects of ethanol on liver, kidney and intestine monooxygenases were studied using hamsters chronically fed with isocaloric control and ethanol-containing liquid diets. The inductive effects of ethanol on liver and kidney aniline hydroxylase activities began to approach plateau level after the animals were fed ethanol for two weeks. Intestinal aniline hydroxylation was refractory to ethanol induction. In control and ethanol-fed hamsters, CO-difference spectra of hepatic and extrahepatic microsomes differed in absorption maxima. Chronic alcohol consumption caused significant increases of cytochrome P-450 and cytochrome b5 contents of liver and kidney microsomes. The increases of the heme proteins were associated with the induction of aniline hydroxylase, N-nitrosodimethylamine demethylase and 7-ethoxycoumarin 0-deethylase activities. In contrast to the liver and kidney, intestinal microsomal cytochromes P-450 and b5 contents in ethanol-treated animals were lower than the controls. Ethanol pretreatment was without effect on intestinal monooxygenase activities toward the metabolism of aniline, N-nitrosodimethylamine, 7-ethoxycoumarin and benzo(a)pyrene. Gel electrophoresis of tissue microsomes from control and ethanol-treated hamsters revealed that ethanol treatment enhanced the intensity of the protein band(s) in the cytochrome P-450 molecular weight region in the liver and kidney, but not in the intestine. These results demonstrate that in hamsters the response of monooxygenase to ethanol may vary from tissue to tissue and it is difficult to make a generalization regarding the inducing property of ethanol. The differential effect on cytochrome P-450 may be an important factor in determining the interaction between ethanol and xenobiotic metabolism in animal tissues.
Ueng
T H
TH
Institute of Biochemistry, College of Medicine, National Taiwan University, Taipei, R.O.C.
Ju
J M
JM
Tsai
J N
JN
D000818:Animals; D006224:Cricetinae; D004591:Electrophoresis, Polyacrylamide Gel; D004790:Enzyme Induction; D000431:Ethanol / Q000009:adverse effects*; D007422:Intestines / Q000187:drug effects / Q000201:enzymology*; D007668:Kidney / Q000187:drug effects / Q000201:enzymology*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008647:Mesocricetus; D008861:Microsomes / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000096:biosynthesis*; D009928:Organ Specificity
D000431:Ethanol; D006899:Mixed Function Oxygenases