Failure of Estrogens and Androgens to Inhibit Bone Resorption in Tissue Culture

The effects of estrogens, androgens, and glucocorticoids on bone resorption were compared in organ culture. At a concentration of 10(-5) M, corticosterone, testosterone, dihydrotestosterone, dehydroepiandosterone, estradiol, ethinyl estradiol and estrone did not inhibit the release of 45Ca from 19-day fetal rat long bone shafts in control or para-thyroid hormone (PTH)-treated cultures after 2 or 5 days. Cortisol inhibited both control and PTH-stimulated resorption at 10(-5) M and 10(-6) M. 17beta-Estradiol was inhibitory at 3 X 10(4) M. However, it was less effective than the estrogenically inactive epimer 17alpha-estradiol, in 8 day control cultures or in cultures containing low concentrations of PTH. At 10(-5) m, neither 17beta-estradiol nor 17alpha-estradiol inhibited resorption stimulated by prostaglandin E2 or by osteoclast activating factor.