Œstradiol et cartilage : données récentes et hypothèses d'action.

Abstract

Cartilage is a hormone-sensitive tissue and since cartilage cells were recently shown to contain nuclear receptors for estradiol (ER), this tissue should be considered as a target organ for this hormone. The cartilage ER is a high affinity receptor, but the number of ERs in cartilage cells is Io rv and there is no information about its variability with age or ageing process. The mechanism by which estradiol interacts with cartilage cells is poorly understood. Estradiol seems to act on chondrocytes as a differentiating factor with no effect on cellular proliferation. In human as well as in animal cartilage cells in vitro, estradiol increases the amount of proteoglycans and collagen type II secreted into culture medium. This effect of estradiol is observed at physiological concentrations and is dose-dependent, due either to increased biosynthesis or decreased degradation of these proteins. On the contrary, pharmacological doses of estradiol decrease the extracellular content of proteins. Recent observations suggest that estradiol could also prevent tile degradative or the local inflammatory processes occurring in cartilage during degenerative cartilage diseases.