Androgen-accelerated bone maturation in mice is not attenuated by Faslodex, an estrogen receptor blocker

Androgens accelerate bone maturation, but it is unclear to what extent this process may be mediated by estrogens derived from aromatization of androge ns, In this study, we investigated whether an estrogen-blocking agent, Fasl odex (ICI 182,780), can attenuate testosterone-accelerated skeletal maturat ion in immature mice. On days of Life 2-8, mouse pups received either testo sterone propionate (50 mug/100 g body weight), Faslodex (100 mug/100 g body weight), a combination of Faslodex + testosterone, or vehicle alone, Skele tal maturation was assessed in the forepaw and the lumbar spine, Testostero ne caused acceleration of bone maturation (p < 0.05, compared with vehicle) , predominantly of axial bones, Faslodex, however, failed to block the effe ct of testosterone, such that the mice receiving Faslodex + testosterone ha d skeletal maturation scores similar to those treated with testosterone alo ne. These results suggest that androgens have the capacity to stimulate bon e maturation directly, probably via their own receptors, (Bone 28:410-413; 2001) (C) 2001 by Elsevier Science Inc. All rights reserved.