In vitro study of the action of estrogens on the human Endometrium: Analysis of the Distribution of Chondrocyte Sulfate and Estrogen Receptors

The cellular and molecular bases of endometrial phisiology are still not well stabilished. The endometrium is under influence of sexual hormones and local factors, which determine morphological ciclic changes preparing the tissue for embryo implantation. If pregnancy doen' t happens, the menstruation occurs. Abundant uterine bleeding is a comum problem, and Premarim (R) (conjugated estrogens) is a treatmnent option, but its mechanismo of action is still unknown. In the 70' it was thought that it acted on physical properties of the ground substance. As the proteoglycans are one of the constituents of extracellular matrix (ECM) envolved with these properties, in this study, by an in vitro approach, we analysed a possible action of conjugated estrogens on human endometrial ECM with special enphasis in sulfatated glycosaminoglycans (GAGs) and also the estrogen receptors (ER), using histochemical, biochemical and immunohistochemical techniques. Organotipic culture of endometrium wal treated with high doses of conjugated estrogens and physiological e supra-physiological doses of 17 beta Estradiol for 2 and 4 hours. The most relevant and original result obtained in this study was the predominance of chondroitin sulfate (CS) over the other sulfated GAGs (dermatan and heparan sulfate), wich was distributed in an homogeneous form for all over the stroma, more concentrated around glands and blood vases, and a little bit more abundant in the proliferative phase. A diminution in tehconcentration of CS staining was seen in secretory endometrium after treatment with high doses of estradiol, and less significative with conjugated estrogens. There was an increased of ER content in proliferative endometrium after treatment with estradiol. Our results sugest that human endometrium CS distribution is modulated by oestrogens, in a fast way and probably withot the participation of nuclear receptors, and raise the question of its participation in the rearangement in ECM molecules during decidualization and embryo implantation process.