Teratogenic Effects of Blue Cohosh (Caulophyllum thalictroides) in Japanese Medaka (Oryzias latipes) are Mediated through GATA2/EDN1 Signaling Pathway

Abstract

Blue cohosh (Caulophyllum thalictroides) (BC) has been used widely to induce labor and to treat other uterine complications [1]. However, the safety and effectiveness of this herbal product has not yet been evaluated by the Food and Drug Administration (FDA) of the USA. Several conflicting reports indicated that the root extract of BC is a teratogen, and by some unknown mechanisms, is able to induce cardiovascular malfunctions in newborn babies. To understand the mechanism we have used Japanese medaka (Oryzias latipes) embryo-larval development as the experimental model and methanolic extract of BC root as the teratogen. The embryo mortality, hatching efficiency, morphological abnormalities in craniofacial and cardiovascular systems and several biochemical parameters are considered for the evaluation of BC toxicity. Our results indicate that BC is able to disrupt cardiovascular and craniofacial cartilage development in medaka embryo in a dose and developmental stage-specific manner. Moreover, embryos precirculation are to some extent more resistant to BC than ones with circulation. Biochemical analyses are unable to establish an effect of BC in total protein, RNA and DNA contents and in the expression of emx2, en2, iro3, otx2, shh, wnt1 and zic5 mRNAs in circulating embryos. However, in precirculating embryos, total RNA content and shh mRNA expression was reduced after BC treatment. By using subtractive hybridization, we are able to demonstrate that gata2 mRNA was differenzially expressed in the circulating embryos after BC treatment. Further analysis identified the rapid expression of gata2 mRNA followed by preproendothelin1 (edn1) mRNA by BC which might be able to induce vasoconstriction and cardiovascular defects in medaka embryo. We therefore conclude that cardiovascular disruption in medaka embryogenesis by BC is probably mediated through Gata2-Edn1 signaling pathway. Acknowledgements: This work was supported by the United States Food and Drug Administration (FDA) 5U01FD002071–09, National Center of Natural Product Research, Environmental Toxicology Research Program and Department of Pharmacology of the University of Mississippi.