Effects of two hexachlorobiphenyl isomers on ornithine decarboxylase induction: inhibitory effects correlate with aryl hydrocarbon hydroxylase activity.
The effects of 2,2',4,4',5,5'-hexachlorobiphenyl (2,4,5-HCB) or 3,3',4,4',5,5'-hexachlorobiphenyl (3,4,5-HCB) on hepatic ornithine decarboxylase (ODC) induction by dexamethasone were investigated. At one week after a single i.p. dose of corn oil or 2,4,5,-HCB and 4 h after administration of dexamethasone, rats exhibited 50- to 60-fold increases of ODC activity. However, rats that had received 3,4,5-HCB in place of 2,4,5-HCB exhibited only a 8-fold increase in ODC activity in response to dexamethasone administration. 2,4,5-HCB administration resulted in increased hepatic aryl hydrocarbon hydroxylase (AHH) activity. Administration of 3,4,5-HCB produced increased AHH activity and decreased N-demethylase activity. It is suggested that the ODC-inhibitory effects may have resulted from Ah-receptor-mediated events.
D000633:Aminopyrine N-Demethylase / Q000378:metabolism; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D001835:Body Weight / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology; D004790:Enzyme Induction; D007536:Isomerism; D008099:Liver / Q000201:enzymology; D008297:Male; D009955:Ornithine Decarboxylase / Q000096:biosynthesis*; D011078:Polychlorinated Biphenyls / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D003907:Dexamethasone; D011078:Polychlorinated Biphenyls; D001189:Aryl Hydrocarbon Hydroxylases; D000633:Aminopyrine N-Demethylase; D009955:Ornithine Decarboxylase; C027309:3,4,5,3',4',5'-hexachlorobiphenyl; C014024:2,4,5,2',4',5'-hexachlorobiphenyl