Exploring the role of hormones in osteoporosis
For many years it was believed that estradiol was recognised by a single form of the estrogen receptor (ER) in human osteoblasts (bone-forming cells). The hormone then activated specific molecular mechanisms, set in motion by the activation of that form of ER. New findings suggest, however, that there is at least one other form of the ER, with which estradiol is found to interact in human osteoblasts. The 'new' form of ER is of smaller size compared to the one identified originally. Although the implications of this observation are unclear, it suffices to assume that a number of conclusions on the action of estradiol in human tissue will have to be re-evaluated. In other words, this new information will have to be included in the models used to explain the involvement of estradiol in bone formation. In terms of developing new chemotherapeutic regimens targeting the estradiol-ER interaction, current approaches will have to be altered. Further research is required to elucidate the mechanism of action and interaction of estradiol with the new forms of the ER. Once a clear model can be presented, groups involved in the development of novel therapeutics will be in a position to ascertain the importance of these new findings.