Effects of benzo[a]pyrene on gilthead seabream (Sparus aurata L.) hepatocytes exposed in vitro to short and long term trials

In the present study, cytotoxic effects of the polycyclic aromatic hydrocarbons benzo[a] pyrene (B[a]P) were investigated in Sparus aurata hepatocytes primary cultures after acute and chronic exposure. Cells were treated with a wide range of B[a]P doses (1 pg/mL to 100 µg/mL) for 24, 48 and 72 h. B[a]P toxicity was quantified in sea bream hepatocytes by MTT assay and immunofluorescence analysis of apoptosis after the various exposure periods, in order to evaluate the hepatic damage and toxicity range. Results showed three cytotoxic responses: B[a]P cell death for primary necrosis after exposure to high concentrations for short times, apoptosis induction with the use of sublethal doses and cell proliferation allied with neoplastic foci formation after exposure to low concentrations for long times. This responses provided an interesting correlation between the damage caused on hepatocytes and the metabolism of this toxic compound, to date mainly studied in vivo. Additionally, the statistical analysis revealed that the effects of time and dose were significant for both parameters and especially the time was extremely significant (P<0.0001), in fact B[a]P induced damage that increased over time. Our findings demonstrated and confirmed that S. aurata is a very sensitive species to B[a]P exposure since adverse effects were found at all tested doses. Furthermore, the new in vitro animal model can be considered a useful tool for studying the cellular effects induced by any contaminant harmful for farmed fish.