THE EFFECT OF CADMIUM ON VITELLOGENIN METABOLISM IN ESTRADIOL-INDUCED FLOUNDER (PLATICHTHYS-FLESUS (L)) MALES AND FEMALES

The effect of cadmium on metabolic processes related to vitellogenic reproduction was investigated in flounder males and females. One injection of 2 mg cadmium per kg body wt reduced the ratio of RNA to DNA in the liver to less than half of the control value and significantly depressed the concentration of the yolk-precursor protein vitellogenin in the plasma of estradiol-injected female flounders. A dose of 0.5 mg cadmium per kg body wt had no effect. In estradiol-induced flounder males cadmium treatment had a significant reducing effect on the level of circulating vitellogenin in the combined estradiol-cadmium treated group compared to the estradiol treated group. No effect of cadmium was observed on the ratio of hepatic RNA to DNA in the male fish. Of the investigated tissues the liver was the most important organ accumulating cadmium in male as well as in female flounders. By gel fractionation, it was found that 88% of the accumulated cadmium in the cadmium-estradiol treated group and only 49% in the cadmium treated group were bound to small cytosol proteins (metallothioneins) indicating that estradiol interferes with the cadmium accumulating ability of the liver. © 1990.