ヒブナ

Intraperitoneal injection of 25 mg/l00g of PCB (polychlorinated biphenyls, Aroclor 1248) to goldfish stimulated the metabolism of progesterone, estradiol-17β, testosterone and cortisol by liver microsomes : the activity of progesterone hydroxylase was increased by 52% in the PCB treated group 6 days after injection, while those of estradiol-178, testosterone and cortisol hydroxylases were elevated by 25%, 51% and 44%, respectively. Significant decreases in plasma levels of progesterone, estradiol-17β, and testosterone were also observed in the fish treated with PCB: the plasma levels of progesterone and estradiol-17β in female fish were lowered by 56% and 35%, respectively, while that of testosterone in male fish was reduced by 53%. This reduction in circulating sex hormones is probably attributable to the elevated metabolism of these hormones in the liver microsome. As an exception, the plasma level of cortisol was not reduced by PCB treatment. This may be due to an influence of stress on fish.The ability of PCB to change the plasma levels of steroid hormones raises the possibility that PCB accumulated in fish at high concentrations could have a deleterious effect on fish reproduction.