Stimulation of cyclic AMP, 17β-oestradiol and protein synthesis by human chorionic gonadotrophin in human endometrial cells

Abstract

Human endometrial tissue was collected from 30-37 year old ovulatory women and enzymatically dispersed and processed to obtain endometrial stromal cells. Cells (2 x 104/well) were incubated in vitro in the absence (control) or presence of human chorionic gonadotrophin (HCG) (10 IU/well) either for 1 h (to determine cAMP) or for 4 h (to estimate protein synthesis, 17β-oestradiol and aromatase activity). HCG significantly stimulated cellular cAMP content and release in comparison to control. Both cellular accumulation and release of cAMP reached the peak at 10 min and then sharply declined in the absence of phosphodiesterase (PDE) inhibitor or remained steady for 1 h in the presence of PDE inhibitor. Content and release of 17β-oestradiol from stromal cells steeply increased from 30 min to 1 h and then slowly increased for 4 h in response to HCG. Incubation of cells with HCG significantly stimulated (P < 0.01) cellular aromatase activity in comparison to control. HCG stimulated protein synthesis of the cells in two phases, initially at 15 min which remained steady for 1 h and then significantly increased (P < 0.01) between 1 and 2 h. The initial phase of protein synthesis appears to be the direct effect of HCG while the later phase was due to the higher concentration of oestradiol caused by HCG. The initial phase of protein synthesis was inhibited by cycloheximide but not by actinomycin D, whereas the later phase of protein synthesis was inhibited both by cycloheximide and actinomycin D. Results therefore indicate a probable mechanism of HCG action on stromal cells and demonstrate the physiological relevance of gonadotrophin receptor in human endometrial cells reported earlier from this laboratory.