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 10−5M, 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 parathyroid hormone (PTH)-treated cultures after 2 or 5 days. Cortisol inhibited both control and PTH-stimulated resorption at 10−5 and 10−6M. 17β-Estradiol was inhibitory at 3 × 10−4M. However, it was less effective than the estrogenically inactive epimer 17α-estradiol, in 8 day control cultures or in cultures containing low concentrations of PTH. At 10−5M, neither 17β-estradiol nor 17α-estradiol inhibited resorption stimulated by prostaglandin E2 or by osteoclast activating factor. (Endocrinology 98: 1065, 1976)