Ovarian steroid receptors and activated MAPK in the regional decidualization in rats.

Though the decidua serves a critical function in implantation, the hormonal regulated pathway in decidualization is still elusive. Here we describe in detail the regional distribution and the effects of progesterone receptors (PGR), estrogen receptors (ESR), and MAPK activation on decidualization. We showed an increase in PGR A, PGR B, ESR1, and phosphorylated MAPK3-1 proteins (p-MAPK3-1), but not in ESR2, in the decidual tissue up to Day 8 of pregnancy. PGR was predominantly found in the nuclei of mesometrial decidual cells and of undifferentiated stromal cells where it colocalizes with ESR2 and ESR1. In the antimesometrial decidua, all the receptors showed cytoplasmic localization. MAPK was activated exclusively in undifferentiated stromal cells of the junctional zone between the antimesometrial and mesometrial decidua and at the border of the antimesometrial decidua. Treatment with the progesterone antagonist onapristone and/or the estrogen antagonist faslodex reduced the extent of decidual tissue and downregulated the levels of PGR and ESR1. The expression level of ESR2 was affected only by the progesterone receptor antagonist, while neither the antiprogestin nor the antiestrogen significantly modified the p-MAPK3-1 level. The inhibition of MAPK3-1 phosphorylation by PD98059 impaired the extent of decidualization and the closure reaction of the implantation chamber, and significantly downregulated ESR1. These results confirm a role of both steroid receptors in the growth and differentiation of the different decidual regions and suggest a new function for p-MAPK3-1 in regulating expression levels of ESR1, thereby maintaining the proliferation capacity of stromal cells and limiting the differentiation process in specified regions of decidual tissues.

Progestins inhibit expression of MMPs and of angiogenic factors in human ectopic endometrial lesions in a mouse model.

Progestins are successfully used in the treatment of endometriosis; however, the exact mechanisms of their action are still unsolved. We here focused on the effect of different progestins on parameters of extracellular matrix degradation and angiogenesis involved in the establishment and maintenance of ectopic endometrial lesions. Human endometrium was intraperitoneally transplanted into nude mice. After 7 and 28 days of treatment with progesterone, dydrogesterone, or its metabolite dihydrodydrogesterone, respectively, ectopic lesions were evaluated for proliferation and apoptosis. Expression of estrogen receptor alpha, progesterone receptor-AB, the angiogenetic factors, cysteine-rich angiogenic inducer (CYR61), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGFA) and the matrix metalloproteinase (MMP)-2, -3, -7 and -9 was investigated. Functional impact on angiogenesis was evaluated by density of microvessels and of vessels stabilized by pericytes within the ectopic lesions. Although dydrogesterone significantly reduced proliferation of endometrial stromal cells after 28 days, suppression of apoptosis was independent from progestins. Expression of MMP-2 was significantly reduced by all progestins and MMP-3 by dydrogesterone. In the grafted endometrial tissue, transcription of bFGF was suppressed by progesterone and dihydrodydrogesterone, and VEGFA and CYR61 by dihydrodydrogesterone and dydrogesterone. In parallel, microvessel density was slightly suppressed by progestins, whereas number of stabilized vessels increased. Thus, progestins regulate factors important for the establishment and maintenance of ectopic endometrial lesions.