Naphthalene and β-naphthoflavone effects on Anguilla anguilla L. hepatic metabolism and erythrocytic nuclear abnormalities

Abstract

The effects of a polycyclic aromatic hydrocarbon (PAH) such as naphthalene (NAP)—an environmental contaminant—and β-naphthoflavone (BNF)—a model substance (PAH-like compound)—were investigated in European eel ( Anguilla anguilla L.) over 3-, 6-, and 9-day exposure (0.1–2.7 μM). Both xenobiotics revealed to be strong biotransformation (phase I) inducers. After 3-day exposure, liver ethoxyresorufin O-deethylase (EROD) activity was significantly increased by all NAP and BNF tested concentrations. At 6 and 9 days, liver EROD activity was significantly induced mainly by the highest NAP and BNF concentrations. Liver cytochrome P450 content was significantly induced after 3-day exposure to 0.9 and 2.7 μM BNF and 9-day exposure to 0.1, 0.3 and 0.9 μM NAP. Liver alanine transaminase (ALT) activity was measured as an indicator of hepatic health condition, revealing a significant decrease after 6-day exposure to 0.9 μM BNF. Genotoxicity measured as erythrocytic nuclear abnormalities (ENA) was detected in all BNF treated fish on day 6, whereas on day 9, ENA frequencies returned to control levels, significantly decreasing at 0.9 μM BNF exposure. Immature erythrocytes (IE) frequency demonstrated a decreasing tendency along the BNF experiment and concomitantly with the above ENA response. The present experimental results elect EROD activity in A. anguilla as a useful short- to medium-term biomarker of exposure to both PAH and PAH-like compounds. However, some problems can emerge in the presence of high xenobiotic concentrations. Concerning genotoxicity, it is hypothesized that ENA response depends on different factors such as the exhaustion of the detoxification process, the balance erythropoiesis/erythrocytic catabolism and the DNA repairing capacity.