Steroid hormone receptor expression and action in bone

The skeleton is a complex tissue, and hormonal control of bone remodelling is elaborate. The important role that steroid hormones play in bone cell de velopment and in the maintenance of normal bone architecture is well establ ished, but it is only relatively recently that it has become possible to de scribe their precise mechanism of action. This review focuses not only on t he steroid hormones (oestrogens, corticosteroids, androgens and progesteron e), but also on related hormones (vitamin D, thyroid hormone and the retino ids), all of which act via structurally homologous nuclear receptors that f orm part of the steroid/thyroid receptor superfamily. By examining the acti ons of all of these hormones in vivo and in vitro, this review gives a gene ral overview of the current understanding of steroid hormone action in bone . In addition, a comprehensive review of steroid hormone receptor expressio n in bone cells is included. Finally, the role that future developments, su ch as steroid hormone receptor knockout mice, will play in our understandin g of steroid hormone action in bone is considered.