Acute effects of benzo[a]pyrene on liver phase I and II enzymes, and DNA damage on sea bream Sparus aurata

Abstract

In the present study biotransformation and detoxification responses to acute exposure to the polycyclic aromatic hydrocarbons benzo[a]pyrene (B[a]P) were investigated in the liver of Sparus aurata (sea bream). Sexually immature gilthead sea bream were treated by intraperitoneal injection of B[a]P (20 mg kg(-1)) for 6, 12, 24, and 48 h. B[a]P accumulation was quantified in sea bream liver by mean of gas phase chromatography (GPC-MS) after the various exposure periods. The following biological responses were measured: (1) ethoxyresorufin-O-deethylase (EROD) activity, as a phase I biotransformation parameter; (2) liver glutathione S-transferase (GST) activity as a phase II conjugation enzyme. DNA damage was assessed over time using the single-cell gel electrophoresis comet assay. B[a]P bioaccumulation in the liver resulted in a biphasic curve with an increasing uptake up to 5.55 +/- 0.67 microg g(-1) dry weight after only 6 h exposure and 4.67 +/- 0.68 microg g(-1) dry weight after 48 h exposure. EROD activity showed a nonsymmetrical bell-shaped kinetic with a maximum at 24 h and lower but significant activities at 12 and 48 h with respect to control animals. Hepatic GST activities were only significant after 48 h exposure. Comet assay showed an increase in liver cells DNA damage with a maximum after 48 h exposure reaching up to 12.17 % DNA in the tail.

Effects of Benzo[a]pyrene on Gilthead Sea Bream (Sparus AurataL.) Hepatocytes Exposedin Vitroto Short and Long Term Trials

“…On the contrary, the data showed a pronounced Phase I biotrasformation, measured as EROD activity, when liver B[a]P uptake was minimal (after 24 h) suggesting a maximum B[a]P liver metabolism after only 24 h. Such results demonstrate a strong liver induction of Phase I enzymes (mediated by cytochrome P450-dependent monooxygenases) involved in the metabolism of B[a]P. Since their activity is evident only few hours after the exposure and reaches the plateau within 24 h (Banni et al, 2009). The early activation hepatic enzymes in sea bream after B[a]P treatment is also confirmed in other in vivo studies (Viarengo et al,1997;Gravato and Santos, 2002).…”

“…Particularly, cells treatment with the highest concentrations of B[a]P led to a significant cell death for primary necrosis within 24 h. This early lethal effect agrees with the B[a]P metabolism studied in vivo in Teleosts by several authors. Banni et al(2009) found that liver uptake of B[a]P after intraperitoneal injection of S. aurata shows a bifasic behaviour reaching the maximum level after 6 h, followed by a decreasing phase till 24 h and a subsequent new increase.…”

“…PAHs exert their toxicity following biotransformation to toxic metabolites, which can be bound covalently to DNA, RNA and proteins causing cell damage, mutagenesis, teratogenesis and carcinogenesis, particularly in the liver (Tuvikene, 1995;Xu et al, 2011). Although sev-eral in vivo studies have been focused on the hepatic metabolism, adduct formation and erythrocytic genotoxic responses to PAHs in sea bass and gilthead sea bream as they are considered very sensitive species (Lamaire et al, 1990(Lamaire et al, , 1992Rodriguez-Ariza et al, 1999;Gravato et al, 2000;Santos, 2002, 2003;Ortiz-Delgado and Sarasquete, 2004;Banni et al, 2009), no data are available in literature on the toxic effect of benzo[a]pyrene in Sparus aurata hepatocytes. Consequently, this work was carried out to overcome this lack applying an innovative in vitro animal model as S. aurata hepatocytes in primary culture, as required by the latest European directives on replacement of in vivo studies (EC, 2006).…”

The Dose–Response Relationships for EROD and GST Induced by Polyaromatic Hydrocarbons in Carassius auratus

“…These results are supported by previous studies on other species, treated by different intraperitoneal PAHs injections. Benzo(a)pyrene displayed strong liver EROD and GST induction potency in S. aurata (Banni et al 2008). Phenanthrene was found to induce a concentration-dependant formation of the enzyme EROD in the tilapia, Oreochromis mossambicus.…”

Mixtures of benzo(a)pyrene, dichlorodiphenyltrichloroethane and tributyltin are more toxic to neotropical fish Rhamdia quelen than isolated exposures

“…The use of IP injections to expose aquatic animals to chemical pollutants is a common approach in ecotoxicological investigations (Banni et al, 2009;Nacci et al, 2002;Nahrgang et al, 2009;Padrós et al, 2003;Wang et al, 2006Wang et al, , 2008. A previous study of our research group (unpublished data) showed that intra-peritoneal injection of radiolabelled 14 C-BaP and 113 Sn-TBT in Fundulus heteroclitus did not differ from dietary exposure in regard to tissue distribution of the contaminants.…”