Influence of progesterone on endometrial nitric oxide synthase expression

ObjectiveTo determine the effect of P on nitric oxide synthase (NOS) expression in human endometrial epithelial cells.DesignLaboratory-based study.SettingUniversity-based research institute.Patient(s)None.Intervention(s)The effect of P on the expression of NOS protein isoforms was examined in an in vitro preparation.Main Outcome Measure(s)The expression of NOS and phosphorylated endothelial NOS (peNOS) protein in human endometrial-derived epithelial cells (HES cells) and messenger RNA (mRNA) in human primary endometrial cell culture.Result(s)Progesterone induced a concentration- and time-dependent stimulation of endothelial NOS (eNOS), inducible NOS (iNOS), and peNOS protein in HES cells. Progesterone also stimulated eNOS and iNOS mRNA in human primary endometrial cells. The effect of P on eNOS and iNOS was completely blocked by RU486 but was partially blocked in case of phosphorylated eNOS. RU486 alone had an inhibitory effect on expression of eNOS but not iNOS protein at a concentration of 10−5 mol/L. Progesterone stimulated phosphorylation of eNOS within 30 minutes, and this effect was completely blocked by an inhibitor of PI3/Akt pathway, wortmannin, and by the extracellular signal–regulated kinase 1,2 pathway blocker UO126.Conclusion(s)Progesterone has both genomic and nongenomic effects to stimulate the expression of NOS in HES cells. The nongenomic action of P on NOS phosphorylation is mediated by the PI3/Akt and extracellular signal–regulated kinase 1,2 pathways.