抄録
Retinoic acid receptor (RAR) α and retinoid X receptor (RXR) α are key factors in a nuclear receptor-dependent signal. To evaluate the effects of bisphenol A (BPA), a candidate endocrine disruptor (ED), on embryonic development, we examined the mRNA levels of RARα and RXRα in murine embryos, exposed in utero to BPA (2 μg/kg/day) at 6.5-17.5 days post-coitum (dpc), by the real-time reverse transcription-polymerase chain reaction (RT-PCR) method. Higher levels of RARα mRNA in cerebra of male and female embryos of control groups were detected at 14.5 dpc. In utero BPA reduced the RARα mRNA expression. Higher levels of RXRα mRNA in cerebra of male and female embryos were seen at 12.5 dpc. The exposure decreased RXRα mRNA expression in male but not female embryos. No remarkable change in the RARα mRNA expression level was noted in cerebella of male or female embryos of the control group during embryonic development. Exposure to BPA increased expression levels of RARα mRNA in cerebella of male and female embryos at 12.5 dpc. Higher levels of RXRα mRNA in cerebella of male and female embryos were seen, but no remarkable changes were noted during embryonic development. BPA significantly decreased the expression levels of RXRα mRNA in cerebella of female embryos at 12.5, 14.5 and 18.5 dpc. RARα and RXRα mRNAs were expressed in gonads (testes and ovaries) of murine embryos from 12.5 to 18.5 dpc. In utero exposure to BPA decreased levels of RARα mRNA in testes of 14.5- and 18.5-dpc-embryos, levels of RXRα mRNA in testes of 14.5-dpc-embryos, and levels of RXRα mRNA in ovaries of 14.5-dpc-embryos. The present findings indicate that RARα and RXRα play crucial roles in organogenesis, and the growth and development of murine embryos, and will contribute to the assessment of the toxic effects of BPA on retinoid signals in embryogenesis.
