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KMID : 0893420070080010027
Journal of Veterinary Science
2007 Volume.8 No. 1 p.27 ~ p.38
Estrogen receptor independent neurotoxic mechanism of bisphenol A, an environmental estrogen
Lee Yoot Mo

Seong Min Jae
Lee Yong Kyung
Lee Tae Myoung
Nam Sang-Yoon
Kim Dae-Joong
Yun Young Won
Kim Tae Seong
Han Soon Young
Hong Jin Tae
Abstract
Bisphenol A (BPA), a ubiquitous environmental contaminant, has been shown to cause developmental toxicity and carcinogenic effects. BPA may have physiological activity through estrogen receptor (ER) -¥á and -¥â, which are expressed in the central nervous system. We previously found that exposure of BPA to immature mice resulted in behavioral alternation, suggesting that overexposure of BPA could be neurotoxic. In this study, we further investigated the molecular neurotoxic mechanisms of BPA. BPA increased vulnerability (decrease of cell viability and differentiation, and increase of apoptotic cell death) of undifferentiated PC12 cells and cortical neuronal cells isolated from gestation 18 day rat embryos in a concentration-dependent manner (more than 50 ¥ìM). The ER antagonists, ICI 182,780, and tamoxifen, did not block these effects. The cell vulnerability against BPA was not significantly different in the PC12 cells overexpressing ER-¥á and ER-¥â compared with PC12 cells expressing vector alone. In addition, there was no difference observed between BPA and 17-¥â estradiol, a well-known agonist of ER receptor in the induction of neurotoxic responses. Further study of the mechanism showed that BPA significantly activated extracellular signal-regulated kinase (ERK) but inhibited anti-apoptotic nuclear factor kappa B (NF-¥êB) activation. In addition, ERK-specific inhibitor, PD 98,059, reversed BPA-induced cell death and restored NF-¥êB activity. This study demonstrated that exposure to BPA can cause neuronal cell death which may eventually be related with behavioral alternation in vivo. However, this neurotoxic effect may not be directly mediated through an ER receptor, as an ERK/NF-¥êB pathway may be more closely involved in BPA-induced neuronal toxicity.
KEYWORD
bisphenol A, estrogen receptor, extracellular signal regulated kinase, neurotoxicity
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