Assessing differences between zebrafish and human nuclear receptor activation induced by environmental water extracts

Most in vitro reporter gene bioassays for detecting biological activities in aquatic environments rely on mammalian receptors and may not accurately assess risk for aquatic organisms. This study explored species-specific differences in activation or inhibition of six human and zebrafish nuclear receptors by environmental water extracts from the Czech Republic. Active sampling was conducted at wastewater treatment plants (WWTP) influents and effluents, receiving waters, and ponds; passive sampling in rivers across the Czech Republic, spanning the Bohemian and Moravian regions. A battery of bioassays including human (h) and zebrafish (zf) estrogen receptor-alpha (ERα), androgen (AR), progesterone (PR), glucocorticoid (GR), mineralocorticoid (MR), and pregnane X (PXR) receptors were employed. hERα activity was detected more frequently than zfERα. Detection and responsiveness of AR activity were similar in both human and zebrafish bioassays. hPR activity appeared only in influent of WWTP Protivín, whereas zfPR activity was found in influents of both WWTP Protivín and Vodňany. zfMR activity was detected in both WWTP influents; no hMR activity was observed. zfPXR activity occurred in influents and surface waters, whereas hPXR activity was restricted to WWTP influents. No (anti-)glucocorticoid activity was detected. Our findings indicate that both human and zebrafish nuclear receptor-based bioassays are suitable for monitoring ERα and AR activities, while zebrafish bioassays are better for PR, MR, and PXR activities in fish habitats. These results may guide researchers in selecting the most appropriate bioassay for assessing endocrine activity in waters.