In vivo and in vitro effects of dimethylbenz(a)anthracene on nuclear uptake of estrogen-receptor complex in rat uterus.

A single oral carcinogenic (20 mg) dose of 7,12-dimethylbenz(a)anthracene (DMBA) significantly reduced the uterine nuclear uptake of estrogen-receptor complex with immature Sprague-Dawley rats were injected with 0.05 microng of tritiated estradiol-17beta (E2) 24 hours after DMBA. Incubation experiments with whole uteri or with isolated uterine nuclei showed that DMBA in vitro does not act by reducing estrogen-receptor transformation or transport into nuclei. DMBA may act in vivo by stimulating hepatic degradation of injected estradiol-17beta so that less active form of the steroid reaches target tissues.