Induction of mixed-function oxidase by chronic treatment with 2,3,7,8-tetrachloro-dibenzo-p-dioxin in female rats.
The effect of a 45-week treatment with different doses of 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) (0.01, 0.10 and 1.00 microgram/kg/week) was evaluated in female rat liver by determining cytochrome P-450 and b5 content and the activities of the enzymes cytochrome c reductase, aryl hydrocarbon hydroxylase (AHH) and 7-ethoxycoumarin O-deethylase (7-ECD); TCDD content in the liver was also measured. Cytochrome b5 and cytochrome c reductase were unaffected at any of the dose levels and cytochrome P-450 was significantly induced only at the highest TCDD dose, but marked induction of AHH and 7-ECD was apparent when the animals were treated with 0.01 microgram/kg/week; a clear dose-response relationship was present in the induction at the 2 lower doses (0.01 and 0.10 microgram/kg/week). The amount of TCDD found in liver tissue (1050, 4740 and 30 700 ppt, respectively, for 0.01, 0.10 an 1.00 microgram/kg/week) indicated a relatively higher accumulation of this compound at lower doses.
D000818:Animals; D003580:Cytochromes / Q000032:analysis / Q000378:metabolism; D004147:Dioxins / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D008099:Liver / Q000032:analysis / Q000201:enzymology*; D008862:Microsomes, Liver / Q000032:analysis / Q000187:drug effects; D006899:Mixed Function Oxygenases / Q000096:biosynthesis*; D010088:Oxidoreductases / Q000096:biosynthesis*; D000072317:Polychlorinated Dibenzodioxins / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats
D003580:Cytochromes; D004147:Dioxins; D000072317:Polychlorinated Dibenzodioxins; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases