Estrogen enhances induction of cytochrome P-4501A1 by 2,3,7, 8-tetrachlorodibenzo-p-dioxin in liver of female Long-Evans rats.
A human carcinogen, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces liver tumors in female rats. In this study, we examined the effects of estrogen on an arylhydrocarbon receptor (AhR)-responsible protein, CYP1A1 expression induced by TCDD in female rat livers. The induction of CYP1A1 by a dose of 300 ng TCDD/kg and its resultant enzymatic activity were significantly enhanced by 5 microg 17beta-estradiol/kg body weight treatment to both intact and ovariectomized rats. Immunoblot analysis showed a increase in nuclear AhR due to estrogen, TCDD or both, suggesting that estrogen is involved in the activation of CYP1A1 gene after the formation of AhR-TCDD complex.
Sarkar
S
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Chemical Exposure and Health Effects Research Team, Regional Environment Division, National Institute for Environmental Studies, Ibaraki 305-0053, Tsukuba, Japan.
Jana
N R
NR
Yonemoto
J
J
Tohyama
C
C
Sone
H
H
D000818:Animals; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis* / Q000235:genetics; D004347:Drug Interactions; D004790:Enzyme Induction; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D015151:Immunoblotting; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D051381:Rats; D020318:Rats, Long-Evans; D018336:Receptors, Aryl Hydrocarbon / Q000032:analysis; D011960:Receptors, Estrogen / Q000032:analysis; D013723:Teratogens / Q000633:toxicity*
D004967:Estrogens; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D011960:Receptors, Estrogen; D013723:Teratogens; D019363:Cytochrome P-450 CYP1A1