In vitro effects of polycyclic aromatic hydrocarbons on sex steroid production by Arabian sea bream Acanthopagrus arabicus ovarian cells

Abstract

Polycyclic aromatic hydrocarbons (PAHs), considered endocrine disruptors, affect the animals reproduction by interfering with the production of sex steroids. In the present study, the in vitro effects of selected PAHs (naphthalene, phenanthrene and BaP) on steroid production of cultivated ovarian cells from Arabian sea bream (Acanthopagrus arabicus) was assessed. Ovarian cells were cultured in Leibovitz L-15 (L-15) medium containing naphthalene, phenanthrene and benzo(a)pyrene with or without androstenedione (AD) as precursors and17b-estradiol (E2), progesterone (P4) and testosterone (T) were then measured. The effects of selected PAHs on the steroidogenic enzyme systems cytochrome P450 17, 20-lyase (P450-17,20l) and cytochrome P450 aromatase (P450-arom) were also compared with the ketoconazole (KCZ) action as inhibitor of cytochrome P450 steroidogenic enzymes (cytochrome P450 17, 20-lyase (P450-17,20l)) and cytochrome P450 aromatase (P450-arom). Adding exogenous androstenedione as a steroid precursor significantly increased the production of all three steroid hormones by cultured ovarian cells. On the other hand, the addition of ketoconazole significantly reduced the production of E2 and P from ovarian cells, while it had no effect on the production of T. This result showed that ketoconazole only affects the cytochrome P450 steroidogenic enzymes and has no effect on the 17-beta-hydroxysteroid dehydrogenase (17-βHSD) enzyme that convert androstenedione to testosterone. On the other hand, a significant decrease in the production of all three steroids (17β-estradiol, progesterone, and testosterone) from ovarian cells exposed to the studied pollutants (naphthalene, phenanthrene, and benzo(a)pyrene) even in the presence of androstenedione indicated that PAHs inhibit all three steroidogenic enzyme systems including P450-17,20l, P450-arom, and 17b-HSD. In conclusion, PAHs are potent inhibitors of the steroidogenic enzyme system including P450-17,20l, P450-arom, and 17b-HSD, and therefore, they can disturb the reproduction of fish living in contaminated areas due to impairment of steroid biosynthesis.