The role of human chorionic gonadotropin on decidualization of endometrialstromal cells in vitro

Although decidualization of endometrial stromal cells (ESC) is crucial for blastocyst implantation and maintenance of pregnancy, its complex mechanism still remains largely unknown. It has long been believed that hCG can dire ctly induce in vitro decidualization of ESC via cAMP signaling. Recently, h owever, it has been reported that the LH/CG receptor is not present in huma n endometrium, and the direct effect of hCG on decidualization has become c ontroversial. To reevaluate the exact effect of hCG; on decidualization, hu man ESC were isolated and cultured with hCG and/or ovarian steroids. ESC treated with 17 beta -estradiol plus progesterone (E-2/P) transformed m orphologically and produced significant PRL, whereas ESC treated with hCG a lone showed no significant increase in PRL in culture medium and exhibited no morphological changes. Moreover, hCG did not promote E-2/P-induced PRL p roduction or intracellular cAMP accumulation, and protein kinase A inhibito r failed to block E-2/P-induced PRL production. These results suggest that hCG does not directly affect in vitro decidualiz ation of human ESC and that the process of E-2/P-indueed in vitro deciduali zation might consist of several pathways, including the intracellular cAMP signaling cascade.