Influence of estradiol on the benzo(a)pyrene hydroxylase activity induced by hexachlorocyclohexane.
Basal BP-hydroxylase activity was measured in male Swiss mice from the age of 3 weeks to 20 months. Maximal enzyme activity was at the age of 5 months. Comparison of the inducibility of BP-hydroxylase by HCH was also investigated in male and female mice of different ages. Male mice showed higher induction of BP-hydroxylase by HCH than females of the same ages. Sterilization of female mice enhanced enzyme induction. Estradiol exhibited competitive inhibition of BP-hydroxylase activity. After treatment with HCH for 8 months, female mice had a lower tumour incidence than males, and this paralleled a lower induction of BP-hydroxylase.
D000375:Aging; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D001579:Benzopyrene Hydroxylase / Q000378:metabolism*; D002369:Castration; D004790:Enzyme Induction / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D001556:Hexachlorocyclohexane / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000139:chemically induced / Q000201:enzymology*; D008297:Male; D051379:Mice; D009374:Neoplasms, Experimental / Q000201:enzymology; D012737:Sex Factors
D004958:Estradiol; D001556:Hexachlorocyclohexane; D001579:Benzopyrene Hydroxylase; D001189:Aryl Hydrocarbon Hydroxylases