No estrogen-like effects of an isopropanolic extract of Rhizoma Cimicifugae racemosae on uterus and vena cava of rats after 17 day treatment

Uterus wet weight was increased after estradiol treatment compared to the negative controls but none of the other treatments including the treatment with iCR had a uterotrophic effect. While estradiol-induced changes in uterine gene expression were mainly analogous to those detectable in shorter term experiments, iCR showed no or slightly antiestrogenic effects on gene expression in the uterus. This is mirrored in the vena cava where iCR had a very minor impact on the expression of the genes analyzed. While C. racemosa is effectively used for treatment of peri- and post-menopausal symptoms for a long time its mechanism of action remains unresolved. Contrary to earlier suggestions C. racemosa does not seem to act as an estrogen agonist, but possibly as a weak antiestrogen.