Response kinetic of EROD in Pejerrey (Odontesthes bonariensis) exposed to a model polycyclic aromatic hydrocarbon

RABUFFETTI, G.; PEREZ, D.E.; BROLA, J.; SOMOZA, G.M.; CARRIQUIRIBORDE, P.

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

SETAC Latin America

Cytochrome p450 plays an important role in xenobiotic compounds detoxification. In particular, the induction of the cyp1a1 gene is regulated by the aryl hydrocarbon receptor (AhR), which is activated by agonist ligands represented by organic aromatic compounds, such as PCBs, dioxins, and polycyclic aromatic hydrocarbon (PAHs). The activity of cyp1a1 encoded enzyme, the 7-ethoxyresorufin-O-deethylase (EROD), has been successfully used as a biomarker to assess exposure to the mentioned pollutants. The aromatic PAH β-naphthoflavone (BNF) is a proven AhR agonist model. The pejerrey, Odontesthes bonariensis, is a native fish from the southern sector of the Del Plata Basin, highly appreciated as a game fish and the quality of its flesh, and very sensitive to aquatic pollution. This study aimed to evaluate the response kinetic of EROD activity in juveniles of O. bonariensis exposed for a duration to a given concentration of BNF and followed by a depuration period. Fish were exposed to a concentration of 100 μg/L BNF for 0 (preexposure), 24, 48, 72, and 96 h (exposure period) and then switched to clean water the following 120, 144, 168, and 192 h (depuration period). The assay was run by quintuplicate, under laboratory conditions, and fish were daily fed, 1 h before media renewal. The enzymatic activity was measured by a fluorometric method. The EROD activity was significantly increased compared to the control group (13 fold) at 24 h of exposure. The highest difference (27 fold) was observed at the end of the exposure period (96 h). In the depuration period, the EROD activity begins to decrease at 120 h, becoming significantly lower than the maximum at 144 h. However, it remained higher than the control (9 fold) even at the end of the experiment. We can conclude the EROD activity is quickly induced by BNF and show a strong response in exposed juveniles of O. bonariensis. The activity is reduced during the depuration period but the recovery is slow remaining significantly induced 96 h after exposure was retired