The endometrium is characterised by its ability to respond to steroids which exert their effects largely through their receptors. The development of antioestrogenic agents with tissue specific properties such as tamoxifen or raloxifene has shown the classical model of steroid receptor action where a hormone is responsible for switching a receptor on or off as too simplistic. It has been shown that steroid receptors require a number of coregulators for their activation and do not necessarily need the steroidal ligand to function but rather depend on peptide growth factors for their activation. The discovery of an additional oestrogen receptor subtype β and the knowledge about interactions between different members of the nuclear receptor family has finally led to a re-evaluation of steroid hormone receptor biochemistry. This review describes the growing understanding regarding the mechanisms of action of steroid receptors in the endometrium.
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