Plasma steroid levels in female flounder (Platichthys flesus) after chronic dietary exposure to single polycyclic aromatic hydrocarbons

The chronic effects of polycyclic aromatic hydrocarbons (PAHs) on ovary dev elopment, total hepatic lipids and plasma sex- and corticosteroid levels in female flounder (Platichthys flesus) were examined. Sexually mature feral female flounder were exposed via the diet to phenanthrene (0.5, 2.5 or 12.5 nmol/g food) or chrysene (0.4 nmol/g food) for 12 weeks, during the previt ellogenic phase of the annual reproductive cycle. PAH exposure did not dire ctly affect germ cell development since no structural and/or developmental differences were observed between control and exposed fish. On the contrary , all treatments resulted in altered plasma steroid levels. The most pronou nced effect was the significant decrease in plasma 17 beta-estradiol to 19 +/- 11%, 27 +/- 7%, 63 +/- 20% and 61 +/- 12% in relation to control fish, respectively, in flounders exposed to 12.5, 2.5 or 0.5 nmol phenanthrene/g food and 0.4 nmol chrysene/g food. Impaired ovarian growth was not observed , most likely because experiments were ended before the period of vitelloge nesis, even though a non-significant general decline in total hepatic lipid s could be observed. Moreover, all exposed flounders, except fish fed with the highest amount of phenanthrene, showed a negative correlation between p lasma 17 beta-estradiol and 17 alpha-hydroxyprogesterone levels (r = -0.46) . One possible explanation is that PAH action may be mediated by a specific inhibition of steroidogenic enzymes. These findings provide evidence that selected PAHs are antiestrogenic xenobiotics with the capability to impair female teleost reproductive function. (C) 2000 Elsevier Science Ltd. All ri ghts reserved.