Aluminium and Cadmium Interfere with the Estrogen Receptor Level in the Primary Culture of Hepatocytes in the Rainbow Trout Oncorhynchus mykiss

Al and Cd-induced inhibition of vitellogenin (VTG) production was examined at the estrogen receptor (ER) level in rainbow trout Oncorhynchus mykiss hepatocytes. The binding of $[^3H]$ $estradiol-17\beta\;(E_2)$ to hepatocytes reached a plateau 3 days after addition of $E_2\;(2\times\;10^{-6} M)$to the medium. The binding activity was linearly reduced with the increased concentrations $(-10^{-5}\;M)$ of 4-hydroxy-tamoxifen (4-OHT) and specific binding linearly increased with the increased doses of $[^3H]\;E_2$, indicating that the radioligand bound to ER. Al $(-10^{-4}\;M)$and Cd $(10^{-6}\;M)$ as well as 4-OHT $(10^{-6}\;M)$ significantly reduced the $[^3H]\;E_2$-binding activity by $30­40\%$, while they completely inhibited VTG production. Al and Cd had no effect on $E_2-human$ $ER\alpha$ binding activity at any concentrations used $(-10^5\;nM\;each)$. These results suggested that Al and Cd inhibited VTG production in part by interfereing with the ER level. Inhibitory effects of these metals on the $E_z-dependent$ upregulation of ER activity are also discussed.