Estradiol 17-β and Progesterone Modulate Inducible Nitric Oxide Synthase and High Mobility Group Box 1 Expression in Human Endometrium

The aim of the present study is to investigate the effects of ovarian sex steroid hormones on the expression and the release of several locally active substances by human endometrium. Specific objectives are (1) to ascertain if estradiol 17-β (E2) and progesterone modulate inducible nitric oxide synthase (iNOS) expression and nitric oxide release; (2) to determine whether human endometrium can express High Mobility Group Box 1 (HMGB1), a multifunctional cytokine, and whether sexual steroid hormones can modulate this expression; and (3) to evaluate whether nitric oxide can influence HMGB1 expression in this tissue. Endometrial tissue was obtained from 40 healthy premenopausal women who underwent hysteroscopy for suspected benign gynecological conditions. Endometrium was incubated with E2, progesterone, or sodium nitroprusside, a nitric oxide donor. Nitrite assay was used to quantify stable nitric oxide metabolites in culture medium, and Western blot analysis was used to detect iNOS and HMGB1. Incubation of...