Effects of vitamin A deficiency on selected xenobiotic-metabolizing enzymes and defenses against oxidative stress in mouse liver.
Male and female C57B1/6 mice were rendered vitamin A-deficient, and the effects of this deficiency on certain xenobiotic-metabolizing enzymes and defenses against oxidative stress were examined. Vitamin A deficiency significantly increased the levels of DT-diaphorase, glutathione transferase, and catalase in the hepatic cytosolic fraction from male mice (5.2-, 1.6-, and 3.5-fold, respectively), as well as from female mice (4.8-, 3.3-, and 2.4-fold, respectively). In the hepatic mitochondrial fraction (containing peroxisomes) from male animals, the activities of urate oxidase and catalase were increased 3.4- and 1.7-fold, respectively. The activity of catalase in the mitochondrial fraction from female mice was not affected by vitamin A deficiency, whereas the activity of peroxisomal urate oxidase was increased 2.9-fold. The hepatic level of ubiquinone was increased somewhat. The significance of the increases observed here is presently unclear, but it may be speculated that vitamin A and/or its metabolites are somehow involved in the down-regulation of these proteins. Another possibility is that these enzymes are increased as a result of hepatic oxidative stress caused by vitamin A deficiency. However, vitamin A deficiency had no effect on the activity of superoxide dismutase in this study, whereas the activity of glutathione peroxidase was slightly decreased (27%) in the hepatic cytosolic fraction from male mice. In addition, the hepatic level of alpha-tocopherol was decreased dramatically in the vitamin A-deficient animals.
Sohlenius-Sternbeck
A K
AK
Unit for Biochemical Toxicology, Department of Biochemistry, Stockholm University, Sweden.
Appelkvist
E L
EL
DePierre
J W
JW
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D005260:Female; D008099:Liver / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009929:Organ Size; D018384:Oxidative Stress / Q000502:physiology*; D012727:Sex Characteristics; D014451:Ubiquinone / Q000378:metabolism; D014802:Vitamin A Deficiency / Q000201:enzymology* / Q000503:physiopathology; D014810:Vitamin E / Q000378:metabolism; D015262:Xenobiotics / Q000378:metabolism
D000975:Antioxidants; D015262:Xenobiotics; D014451:Ubiquinone; D014810:Vitamin E