Modulations of P450 mRNA in liver and mammary gland and P450 activities and metabolism of estrogen in liver by treatment of rats with indole-3-carbinol.

Indole-3-carbinol (I3C), found in cruciferous vegetables, has been shown to suppress tumorigenesis at estrogen-responsive sites. This effect may be mediated through modification by I3C of the cytochrome P450 (CYP) complement and activities leading to estrogen detoxication. In this study, we examined the effects of 4- and 10-day treatments of female Sprague-Dawley rats with I3C at 5, 25, and 250 mg/kg body weight, administered by oral gavage, on CYP mRNA expression in the liver and mammary gland, CYP-dependent activities, and the metabolism of 17beta-estradiol (E2) and estrone (E1) by liver microsomes.