Estrogen withdrawal results in bone loss, research shows that the Estrogen Receptor has a fundamental role

Professor Lance Lanyon, Principal of The Royal Veterinary College, Karla Lee, Helen Jessop, Rosemary Suswillo, Gul Zaman from the Department of Basic Sciences at The Royal Veterinary College have shown in their research that the Estrogen Receptor has a fundamental role in bone cells by adjusting the bone architecture to match the loads individuals place on them. Their paper is published in the latest edition of Nature.

The strain imposed by mechanical loading on bone tissue normally stimulates a response by bone cells that results in an adjustment to bone architecture and enables the bone to withstand reasonable loads. This research centred on why this process should become less effective in some 50 per cent of post-menopausal women who suffered fractures as a result.

This research shows why estrogen withdrawal results in bone loss – the number of Estrogen Receptors is reduced by the estrogen levels. When estrogen levels decline (as at menopause) ER levels also decline to the extent that they limit the bone cells’ adaptive responses to load bearing thus producing an effective environment of disuse or underuse which permits bone loss.

Previous research has concentrated on the effects of estrogen on various processes assuming the Estrogen Receptor is more or less constant. One of the Estrogen Receptor’s possible early reproductive functions may be to induce skeletal remodelling to release calcium for egg-laying or embyonic delvelopment.

Professor Lanyon says: “the ER is amenable to therapy and there may be a way either to regulate it in bone or to affect its activity. For instance Hormone Replacement Therapy will restore the ER number and thus eliminate the restriction on the loading-related response.”