Differential induction of hepatic drug metabolizing enzymes in Japanese quail by 1,2,4-trichlorobenzene.
The effects of single oral administration of 1,2,4-trichlorobenzene (TCB), 200, 400, 800 or 1600 mg/kg, and of daily oral administration of TCB, 400 mg/kg, for 3 consecutive days, on components of the microsomal monooxygenase system, glutathione, and the activities of cytosolic glutathione S-transferase and microsomal epoxide hydrolase in Japanese quail liver were studied. Cytochromes P-450 and b5 contents of liver microsomes and the activities of 7-ethoxyresorufin deethylase (7-ERD) and glutathione S-transferase were significantly increased 1 day after administration of single doses of TCB. Liver GSH and 7-ethoxycoumarin deethylase (7-ECD) activity were unchanged. Microsomal epoxide hydrolase activity was significantly decreased at TCB doses above 400 mg/kg. Increases in cytochromes and activities of 7-ERD and glutathione S-transferase were also seen following the 3-day administration of TCB, 400 mg/kg. In addition, liver GSH and the activity of NADPH-cytochrome c reductase were significantly increased whereas 7-ECD was significantly decreased by the 3-day treatment. These findings indicate that in Japanese quail, TCB is an inducer of 7-ERD and glutathione S-transferase but not of 7-ECD and epoxide hydrolase.
D015660:7-Alkoxycoumarin O-Dealkylase; D000818:Animals; D002722:Chlorobenzenes / Q000378:metabolism / Q000494:pharmacology*; D003370:Coturnix / Q000378:metabolism*; D019363:Cytochrome P-450 CYP1A1; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis; D003573:Cytochrome b Group / Q000096:biosynthesis; D015786:Cytochromes b5; D004790:Enzyme Induction / Q000187:drug effects; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D010088:Oxidoreductases / Q000096:biosynthesis; D010105:Oxygenases / Q000096:biosynthesis; D011784:Quail / Q000378:metabolism*
D002722:Chlorobenzenes; D003573:Cytochrome b Group; C009947:1,2,4-trichlorobenzene; D015786:Cytochromes b5; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D010105:Oxygenases; D015660:7-Alkoxycoumarin O-Dealkylase; D019363:Cytochrome P-450 CYP1A1