ABSTRACT
<p><b>OBJECTIVE</b>To study the estrogen-like action mechanism of Menoprogen on ovariectomized female rats.</p><p><b>METHOD</b>Ovariectomized rat model (OVX) was established and estradiol (17beta-estradiol, E2) was used as positive control. The uterine coefficient and serum E2 level were determined after administration of Menoprogen for 2 weeks. The uterine vascular endothelial growth factor (VEGF), water channel protein (aquaporin, AQP), estrogen receptor (ER), progesterone receptor (PR) and the expression of proto-oncogenes (c-jun, c-fos) were observed by immunohistochemical method. Yeast two-hybrid assay was applied to detect the existence of components combining with ERalpha or ERbeta in Menoprogen.</p><p><b>RESULT</b>Both Menoprogen and E2 could significantly elevate the uterine coefficient of OVX rats, increase the level of serum E2 and up-regulate the expressions of VEGF, AQP2 as well as AQP5 in uterus. E2, not as E2 Menoprogen couldn't promote the expressions of ERalpha, PR, c-jun and c-fos in OVX rat uterus. And yeast two-hybrid assay showed no components combining with ERalpha or ERbeta in Menoprogen.</p><p><b>CONCLUSION</b>Menoprogen has estrogen-like effect, and can be used to treat menopause syndrome. The risk of estrogen-mediated endometrial cancer is low for this treatment because its mechanism is different from estrogen-like substances.</p>