INHIBITORY EFFECTS OF ALUMINUM ON VITELLOGENIN INDUCTION BY ESTRADIOL-17-BETA IN THE PRIMARY CULTURE OF HEPATOCYTES IN THE RAINBOW-TROUT ONCORHYNCHUS-MYKISS

Effects of Al on estradiol-induced vitellogenin (VTG) induction were e lectrophoretically examined in primary hepatocyte cultures in rainbow trout. Hepatocytes were precultured for 2 days and then estradiol-17 b eta (E-2, 6 x 10(-6) M) and Al (10(-6) - 10(-4) M) were added to the i ncubation medium. The hepatocytes were cultured for 5 more days. Spent media were analyzed by SDS-PAGE and the relative rate of VTG synthesi s was evaluated by a measurement of the integrated optical density of the main VTG band and was expressed as the percentage of VTG to total proteins including the VTG. The addition of Al to the incubation mediu m had no effect on the viability of hepatocytes in the culture. Howeve r, it specifically reduced VTG synthesis by hepatocytes in a concentra tion-dependent way and there was a significant reduction at AZ concent rations greater than 6 x 10(-5) M. VTG synthesis by E-2-primed hepatoc ytes was also reduced by Al concentrations of more than 6 x 10(-5) M 2 -6 days after Al addition. Enriched Ca concentrations (1.8 to 2.5 or 5 .0 mM) in the incubation medium had no protective effect on the reduct ion of VTG synthesis by Al. These results suggest that the synthesis o f VTG is more susceptible to Al than are other hepatocyte-derived prot eins. (C) 1998 Academic Press.