Estrogenic Potency of a Bisphenol A Metabolite on Vitellogenin Synthesis in Medaka, Oryzias latipes

Abstract

We investigated the estrogenic activity of a bisphenol A (BPA) metabolite (4-methyl-2,4-bis(p-hydroxyphenyl)-pent-1-ene; MBP) in male medaka (Oryzias latipes) using vitellogenin (Vg, Vg1 and Vg2) as a biomarker. Male d-rR medaka were exposed to various concentrations of estradiol-17β (E₂), MBP and BPA for 3 days, and then the serum Vg concentration was measured using specific chemiluminescent immunoassays. The estimated relative estrogenic activities of MBP and BPA compared with E₂ (100%) were 1.3-1.4% and 0.00010-0.00023%, respectively. These findings indicated that MBP has about 10⁴-fold higher estrogenic potency than the parent BPA and about 1/50 that of E₂ for Vg synthesis in medaka. This is the first study to show that MBP can act as a highly potent estrogen agonist in living organisms.