title: Regulation of cytochrome P450 2B1/2 mRNAs by Kepone (chlordecone) and potent estrogens in primary cultures of adult rat hepatocytes on Matrigel.
abstract: We previously reported that when primary cultures of rat hepatocytes were treated with phenobarbital (PB) or one of several organochlorine pesticides, including Mirex, there was co-induction of cytochrome P450 2B1 and 2B2 mRNAs and immunoreactive proteins, whereas Kepone selectively induced 2B2 (Kocarek et al. (1991) Mol. Pharmacol. 40, 203-210). Indeed, Kepone treatment actively suppressed induction of 2B1 and 2B2 mRNAs in hepatocytes cotreated with phenobarbital. Because Kepone differs chemically from Mirex only in the replacement of 2 chlorine atoms with a ketone group, which exists in aqueous solution as a gem-diol and appears to confer weak estrogenic properties, we treated hepatocyte cultures with one of 3 potent estrogens, beta-estradiol, 17 alpha-ethinylestradiol or diethylstilbestrol. Treatment with each of these estrogens induced 2B1 and 2B2 mRNA only at very high doses (10(-4) M). Beta-Estradiol (10(-4) M) treatment also induced 2B1/2 mRNA in hepatocyte cultures prepared from a prepubescent female rat. The anti-estrogen tamoxifen failed to reverse 2B1/2 mRNA induction following beta-estradiol or Kepone treatment of adult hepatocyte cultures. High doses of beta-estradiol or 17 alpha-ethinylestradiol failed to induce 2B1/2 mRNA in treated rats. We also examined the effects of chloral hydrate, a simple gem-diol, on 2B1/2 mRNA induction in the hepatocyte cultures. Treatment with chloral hydrate (3 x 10(-3) M), like Kepone (10(-5) M), suppressed 2B1/2 mRNA induction following phenobarbital (10(-4) M) treatment, while Kepone alcohol (10(-5) M), which is not a gem-diol, produced less suppression. Our results suggest that selective induction by Kepone of 2B2 is unlikely related to its effects as a weak classical estrogen, while the ability of Kepone to suppress induction of 2B1 and 2B2 by PB may be related to its properties as a gem-diol.
authors.affiliation: Department of Medicine, Medical College of Virginia, Richmond 23298.
authors.forename: T A
authors.initials: TA
authors.lastname: Kocarek
authors.forename: E G
authors.initials: EG
authors.lastname: Schuetz
authors.forename: P S
authors.initials: PS
authors.lastname: Guzelian
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D015152:Blotting, Northern; D002478:Cells, Cultured; D002697:Chloral Hydrate / Q000494:pharmacology; D007631:Chlordecone / Q000633:toxicity*; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000235:genetics; D004054:Diethylstilbestrol / Q000633:toxicity; D004958:Estradiol / Q000633:toxicity; D004967:Estrogens / Q000633:toxicity*; D004997:Ethinyl Estradiol / Q000633:toxicity; D005260:Female; D008099:Liver / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D010634:Phenobarbital / Q000633:toxicity; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013250:Steroid Hydroxylases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D004967:Estrogens; D012333:RNA, Messenger; D002697:Chloral Hydrate; D004997:Ethinyl Estradiol; D004958:Estradiol; D004054:Diethylstilbestrol; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C025619:steroid 16-beta-hydroxylase; D007631:Chlordecone; D010634:Phenobarbital