Dexamethasone-induced changes in endometrial growth and inducible nitric oxide synthase during decidualization in rats

Influence of progesterone on endometrial nitric oxide synthase expression

OBJECTIVE

To determine the effect of P on nitric oxide synthase (NOS) expression in human endometrial epithelial cells.

DESIGN

Laboratory-based study.

SETTING

University-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.

Expression and regulation of inducible nitric oxide synthase from human primary airway epithelial cells

Elevated levels of exhaled nitric oxide are seen in inflammatory airway diseases such as asthma, but the cellular source remains unknown. This study investigated whether human airway epithelial cells express inducible nitric oxide synthase (iNOS). Human bronchial epithelial cells stimulated with 50 ng/ml interleukin-1beta, tumor necrosis factor-alpha, and interferon-gamma express iNOS mRNA, protein and increased nitrite in the cell culture media, which was inhibited by the selective iNOS inhibitor 1400W. Cells derived from subjects with asthma produced less nitrite than cells from normal subjects (6.59 +/- 0.99 microM nitrite, n = 15 versus 3.89 +/- 0.42 microM nitrite, n = 20; P < 0.05). This was not attributed to steroid treatment of subjects with asthma because there was no difference in the amount of nitrite released from steroid-naive and steroid-treated cells (3.51 +/- 0.46 versus 4.27 +/- 0.7 microM nitrite, n = 10). Neither dexamethasone nor budesonide inhibited iNOS mRNA induction, protein expression, or nitrite accumulation. The cells were not steroid insensitive because steroids inhibited GM-CSF release. Therefore, although these cells express iNOS under inflammatory conditions, they do not appear to be regulated directly by glucocorticosteroids.