Estrogen treatment with no side effects in sight, Swedish researchers find

The study is presented in the Proceedings of the National Academy of Sciences.

Many women are affected by osteoporosis after the menopause, when the body's production of estrogen decreases. Estrogen is the hormone that principally strengthens the bone mass in women, and it is also of significance for the skeleton in men. Treatment of osteoporosis with estrogens is, however, associated with serious side effects such as breast cancer and blood clots. In order to develop an estrogen treatment that utilizes the favorable effects of the estrogen but not its side effects, the researchers have analyzed which parts of the estrogen receptor is most important in enabling estrogen to act on bone tissue and other tissues.

Estrogen has recipient molecules known as estrogen receptors, which cause the body to respond to estrogen.

"This is the first study to analyze the significance of different parts of a particular type of estrogen receptor through studies in mice. It enables us to differentiate the favorable effects of estrogen in bone tissue from the adverse effects in other tissues," says Anna Börjesson, a PhD student at the Centre for Bone and Arthritis Research at the Sahlgrenska Academy.

This knowledge improves the prospects of being able to develop new, safer estrogen treatments in the future.

"The development of special estrogens that are tailored to bone and only affect a particular part of this type of estrogen receptor may lead to a more targeted and effective treatment for osteoporosis with minimal side effects," Professor Claes Ohlsson explains.