Using ovarian and brain cell culture from the Mullet, Liza klunzingeri, to assess the inhibitory effects of benzo[a]pyrene on aromatase activity

We assessed the toxic effects of benzo[a]pyrene (BaP) on cell viability, aromatase (Aro) activity and steroid production using ovarian and brain cell cultures obtained from Mullet, Liza klunzingeri. The brain and ovary were minced and digested, and the cells were suspended in Leibovitz's L-15 medium supplemented with 15% and 20% fetal bovine serum. The cell suspensions were seeded on 25-cm(2) cell-culture flasks at 1 x 10(6) cells/mL and incubated at 25 degrees C for 2 weeks. A BaP concentration of 10(-5) mol/L was accepted as the half-maximal inhibitory concentration. Ovarian and brain cells were exposed to different concentrations of BaP [0 (control), 10(-6) , 2 x 10(-6) , 3 x 10(-6) mol/L] and incubated at 30 degrees C. At different sampling times (0, 12, 24 and 48 h) 40 ng/10(5) cells of 1,4,6-androstatriene-3,17-dione (ATD) was added to each well. Aro activity, 17beta-estradiol (E2) and ATD production were determined. The sensitivity of the cultivated ovarian and brain cells to BaP increased dose dependently. BaP was a potent inhibitor of Aro activity at 2 x 10(-6) and 3 x 10(-6) mol/L, both in the cultivated brain and ovarian cells at different sampling times, with 10(-6) mol/L BaP found to be the least potent Aro inhibitor. E2 production decreased from cultivated ovarian and brain cells treated by different concentrations of BaP. In conclusion, BaP is able to change the activity of Aro and disrupt the biosynthesis of estrogens, and thus affects reproduction in fish.