In vitro estrogenic effects of phytoestrogens in rainbow trout and Siberian sturgeon

Soy as several other vegetables is rich in phytoestrogens and we demonstrat ed that these compounds were both estrogenic and endocrine disrupters, in s turgeon and trout, in vivo and in vitro. In our laboratory, we developed se veral in vitro tests in these two species to screen the activity of estroge nic compounds. This paper reports hepatocytes, which synthesise VTG in resp onse to estrogenic stimulation, and in vitro binding tests on hepatic estro gen receptors. These tests showed different reactivities in the two species suggesting a difference of sensitivity, which is also observed in vivo. Fi nally, comparing the two species the in vitro affinity of phytoestrogens fo r estrogen receptors did not reflect the VTG synthesis in hepatocyte cultur es. All these results, together with the tyrosine kinase inhibitory effect of certain phytoestrogens demonstrated by other authors, suggest that the s timulation of the VTG gene transcription may not be explained exclusively b y a simple ligand-receptor-DNA interaction.