Gene Expression Characteristics in the Japanese Medaka (Oryzias latipes) Liver after Exposure to Endocrine Disrupting Chemicals

Endocrine disrupting chemicals (EDCs) are of concerning chemicals due to their ability to make damage or alter hormonal activities in living organisms. In this study, therefore, toxicogenomic analyses using a real time RT-PCR tech- nique have been conducted to characterize the responses of male Japanese Medaka and to provide valuable information about the toxicological properties and their hazardous effects of three EDCs, i.e., 17-beta estradiol (E 2 ), nonylphenol (NP) and bisphenol A (BPA), to Japanese medaka fish. For doing that, the expression kinetics of female-related genes and other cellular toxicity representative genes, including vitellogenin (yolk protein precursor), choriogenin L (inner membrane precursor of egg), cytochrome P450 1A (CYP1A) and heat shock protein 70 (HSP70) were used. Gene expression levels at three different times after exposure with two different concentrations of EDCs were quantified by measuring messenger RNA (mRNA) concentrations in the liver extracts using the Taqman based real-time PCR method. The results showed that E 2 causes a strong estrogenic effect even at a concentration of only 1 ppb, while NP and BPA were found to cause some form of cellular toxicity, and an estrogenic effect with inducing the production of HSP 70, respectively.