Veratrum nigrum inhibits the estrogenic activity of salvia miltiorrhiza bunge in vivo and in vitro.

BACKGROUND: As recorded in the 18 incompatible medicaments of Traditional Chinese Medicine theory, the combined use of Salvia miltiorrhiza bunge (SM) and Veratrum nigrum (VN) could induce toxicity and has been prohibited for thousands of years in China. However, the theory has been validated due to lack of evidence. Previous studies have focused on the chemical constituents that are responsible for the toxicity of the two agents.

PURPOSE: This study offers preliminary insight into the pharmacodynamics and mechanism of estrogenic activity responsible for their incompatibility.

STUDY DESIGN: We undertook a characterization of the interaction between estrogenic activities of SM and VN using in vivo models of immature and ovariectomized (OVX) mice, and in vitro studies focused on the estrogen receptor (ER) pathway for further mechanism.

METHODS: Immature and OVX mice were treated intragastrically with SM at doses of 1.6, 3.2 g/kg, or combine with 0.045 g/kg VN and 0.005 g/kg the ER antagonist ICI182, 780 for elucidating the effects on estrogenic activity in reproductive tissues, E2 secretion, and the ER mechanism. ERα/β binding experiments and ERα/β transcriptional activity were performed in order to evaluate the biological action exerted through ERs.

RESULTS: VN decreased the estrogenic efficacy of SM in promoting the development of the uterus and vagina in immature mice, and reversing the atrophy of reproductive tissues in OVX mice. VN interfered with the estrogenic efficacy of SM by decreasing the serum estradiol and the upregulation of ERα and ERβ expressions in reproductive tissues by treatment with SM. VN antagonized the estrogenic efficacy of SM in promoting the viability of MCF-7 cells and stimulating the binding ability with ERα and ERβ, and increasing ERα/β-estrogen response element (ERE) luciferase activity.

CONCLUSIONS: This study provided evidence that the combined use of SM and VN could induce unfavorable effects. VN decreased the estrogenic activity of SM, which might be related to the regulation of estrogen secretion and ERs through the ER-ERE pathway.