title: A time-course investigation of vitamin A levels and drug metabolizing enzyme activities in rats following a single treatment with prototypic polychlorinated biphenyls and DDT.
abstract: Xenobiotics previously characterized as selective inducers of drug-metabolizing enzymes were chosen to probe possible relationships between enzyme induction and vitamin A metabolism. Liver, kidney and serum retinol and retinyl palmitate levels were investigated in male Sprague--Dawley rats receiving a single i.p. injection of the polychlorinated biphenyls (PCBs), 2,2',5,5'-tetrachlorobiphenyl, 3,3',4,4'-tetrachlorobiphenyl or 2,2',4,4',5,5'-hexachlorobiphenyl (300 mumol/kg) or 1,1,1-trichloro-2,2-bis-(4-chlorophenyl)-ethane (DDT) (150 mumol/kg). While 2,2',5,5'-tetrachlorobiphenyl, a weak or non-inducer, and 2,2',4,4',5,5'-hexaclorobiphenyl and DDT, phenobarbital-type inducers of cytochrome P-450, led to no reduction in total vitamin A content of liver or kidney during the 7 day time-course, administration of 3,3',4,4'-tetrachlorobiphenyl, a toxic PCB and a potent 3-methylcholanthrene-type inducer of cytochrome P-450, resulted in progressively lowered liver vitamin A levels (to 40% of control values by day 7). During this time, kidney total vitamin A content increased 3-fold. The increase in kidney vitamin A (due primarily to increased retinol content) was only equal to 1/40 of total vitamin A which had disappeared from the liver. Although 3,3',4,4'-tetrachlorobiphenyl specifically induced certain drug-metabolizing enzyme activities, e.g. aryl hydrocarbon hydroxylase and UDP-glucuronosyltransferase (toward 4-nitrophenol), no highly significant correlations were found among the vitamin A levels and drug-metabolizing enzyme activities in the liver (aminopyrine N-demethylase, aryl hydrocarbon hydroxylase, aldrin epoxidase, microsomal epoxide hydrolase, UDP-glucuronosyltransferase toward 4-nitrophenol, glutathione transferase toward 1-chloro-2,4-dinitrobenzene and cytochrome P-450 content) as determined by multiple linear regression analysis.
mesh_terms: D000818:Animals; D003634:DDT / Q000633:toxicity*; D004790:Enzyme Induction / Q000187:drug effects; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008297:Male; D006899:Mixed Function Oxygenases / Q000096:biosynthesis*; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D014801:Vitamin A / Q000097:blood / Q000378:metabolism*
chemical_list: D014801:Vitamin A; D003634:DDT; D011078:Polychlorinated Biphenyls; D006899:Mixed Function Oxygenases