Abstract
Treatment of immature female rats with phenobarbital for 4 days stimulates the activity of liver microsomal enzymes that metabolize estradiol-17β and estrone, inhibits the estradiol- or estrone-induced increases in uterine wet weight and decreases the amount of tritiated estrogen found in the uterus after an injection of tritiated estradiol or estrone. Treatment of rats with as little as 1 mg of phenobarbital per kg twice daily for 4 days causes a 37% inhibition in the uterotropic action of a 0.2-µg injection of tritiated estrone, and the concentration of radioactive steroid in the uterus is decreased. The metabolism of estradiol by liver microsomes in vitro is enhanced when the microsomes are harvested from animals pretreated with several unrelated microsomal enzyme inducers such as phenobarbital, chlordane, orphenadrine, chlorcyclizine, norchlorcyclizine and phenylbutazone. Pretreatment of rats with these chemicals also inhibits the action of estradiol on the uterus and decreases the concentration of estradiol in this organ.
Footnotes
- Received August 18, 1967.
- Accepted October 25, 1967.
- © 1968 by The Williams & Wilkins Company
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