Biomarker responses in persian sturgeon (Acipenser persicus) exposed to benzo-a-pyrene and beta-naphthoflavone

Abstract

Biotransformation enzymes of xenobiotics (ethoxyresorufin-O-deethylase, cytochrome P4501A1 content and glutathione-S-transferase) were investigated in the liver of Persian Sturgeon (Acipenser persicus) after a 96-hour exposure to polycyclic aromatic hydrocarbons (PAHs), premutagenic benzo[a]pyrene (BaP) and beta-naphthoflavone (BNF). The fish were injected 10 mg/kg wet-body weight in corn oil for 96 hours every days. Ethoxyresorufin-O-deethylase activity (EROD) and glutathione s-transferase activity (GST) were measured in the fish liver. Cytochrome P4501A1 (CYP1A1) content was estimated by indirect enzyme-linked immunosorbent assay (ELISA). The response appeared as early as 12 hours post exposure. A time-dependent response was observed in the EROD activity, being significantly higher at 48 hours post exposure to 10 mg/kg of BaP. The greatest induction occurred in the fish treated with 10 mg/kg BaP, in which a 32.1- fold increase in EROD activity was observed. Results showed that EROD activity in A. persicus is significantly increased by BaP and BNF treatments. Both chemicals showed higher values of EROD activity compared to the liver CYP1A content. There was a rise in glutathione-S-transferase activity in fish exposed to BNF, but no increase was observed in fish treated with BaP. The results showed that hepatic CYP1A expression in terms of induction of EROD activity might be suited as a biomarker of organic contamination in aquatic environments and led to lower sensitivity of the second phase in the detoxification enzyme.

Keywords

• Biomarkers
• Acipenser persicus
• benzo(a)pyrene
• beta-naphthoflavone