PCR-ELISA detection of estrogen receptor mRNA expression and plasma vitellogenin induction in juvenile sole (Solea solea) exposed to waterborne 4-nonylphenol

In this study, the effect of 4-nonylphenol (4NP) on reproductive axis of sole (Solea solea) has been investigated by using selected biomarkers of estrogenic effects: vitellogenin (VTG) and estrogen receptor beta (ERb) mRNA. Furthermore, an enzyme linked immunosorbent assay (ELISA) detection system of reverse transcriptase-polymerase chain reaction (RT-PCR) products for the analysis of sole ERb mRNA expression was developed and validated. The proposed method allows large-scale analyses of different mRNAs in fast and not expensive way. Our results have demonstrated that the PCR–ELISA method developed shows high sensitivity, good reproducibility and also the potential for semi-quantitative analysis of hepatic ERb mRNAs. Both plasma VTG level and ERb mRNA expression were increased in tested animals following a short exposure to environmental relevant concentrations (10-6 M) of 4NP, confirming the functional role of ERb in the regulation of xenoestrogens-induced production of VTG. The methodology provided in the present study together with the preliminary results on the hepatic expression of ERb may be useful in environmental xenoestrogens monitoring studies, using flatfish as ‘‘sentinel’’ species.