Effects of methylsulphonyl polychlorinated biphenyl homologues and 7,8-benzoflavone on aryl hydrocarbon hydroxylase activity.
First, we investigated the effects of eleven methylsulphonyl polychlorinated biphenyl (MSF-PCB) homologues at 1.5 micrograms/ml and 7,8-benzoflavone (ANF) at 1.4 micrograms/ml on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 15 ng/ml)-induced aryl hydrocarbon hydroxylase (AHH) activity of cultured human lymphoblastoid cells and the following results were obtained. 1) The relative AHH activity (TCDD-induced AHH activity treated with each of the MSF-PCB compounds or ANF/the enzyme activity treated with acetone, %) of the ANF-treated culture was the smallest value (about 9%). 2) Among MSF-PCB homologues, 3-MSF-4,5,3',4'- and 4-MSF-3,5,3',4'-tetrachlorobiphenyls (TCBs) showed the highest inhibition and their relative enzyme activities were about 20%. 3) In the rest of MSF-PCB compounds, the relative AHH activities were as follows: 4-MSF-3,5,3',4',5'-pentachlorobiphenyl (PenCB); 37%, 3-MSF-4,5,2',3',4'-PenCB; 50%, 3-MSF-4,5,2',3'-TCB, 3-MSF-4,5,2',3',4',5'-hexachlorobiphenyl and 3-MSF-4,5,6,2',3',4',5'-heptachlorobiphenyl; 60 to 64%, 4-MSF-2,5,2',3',4'-PenCB; 77%, 3-MSF-2,5,3',4'-TCB; 88%, 4-MSF-2,5,2',5'-TCB; 93% and 3-MSF-4,5,3',4',5'-PenCB rather enhanced the TCDD-induced enzyme activity. Second, we prepared the hepatic microsomes of BALB/c (Ah responsive) and AKR/J (Ah nonresponsive) strains of mice after the treatment of olive oil (as control), 3-methylcholanthrene (MC, 42 mg/kg, once) and TCDD (20 micrograms/kg, 6 times, once every other week) in order to examine the effects of 3-MSF-4,5,3',4'-TCB (1.5 to 45 micrograms/ml) and ANF (1.4 to 42 micrograms/ml) on the respective hepatic microsomal AHH activities.(ABSTRACT TRUNCATED AT 250 WORDS)
Nagayama
J
J
Laboratory of Environmental Health Sciences, School of Health Sciences, Kyushu University, Fukuoka.
Masuda
Y
Y
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D001571:Benzoflavones / Q000494:pharmacology*; D002478:Cells, Cultured; D004790:Enzyme Induction; D006801:Humans; D066298:In Vitro Techniques; D008214:Lymphocytes / Q000187:drug effects / Q000201:enzymology; D008748:Methylcholanthrene / Q000494:pharmacology; D051379:Mice; D008806:Mice, Inbred AKR; D008807:Mice, Inbred BALB C; D008862:Microsomes, Liver / Q000201:enzymology; D011078:Polychlorinated Biphenyls / Q000494:pharmacology*; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology
D001571:Benzoflavones; D000072317:Polychlorinated Dibenzodioxins; D008748:Methylcholanthrene; C011512:alpha-naphthoflavone; D011078:Polychlorinated Biphenyls; D001189:Aryl Hydrocarbon Hydroxylases