Effects of organochlorines on cytochrome P450 activity and antioxidant enzymes in liver of roundnose grenadier Coryphaenoides rupestris

Abstract

Oceans function as a sink for organochlorine compounds (OCs) such as PCBs and DDTs. Deep-sea fish bioaccumulate OCs to levels 10 to 100 times higher than shallow-water species. OCs induce the cytochrome P450 (CYP) system, the activity of which may increase reactive oxygen species (ROS) production in liver cells. However, the susceptibility of fish to the oxidative stress likely caused by OCs remains unclear. We analysed whether PCB and DDT contamination of roundnose grenadier Coryphaenoides rupestris was associated with higher ethoxyresorufin-O-deethylase (EROD) activity (CYP1A-related), and activities of antioxidant enzymes such as catalase (CAT), superoxide dismutases (SOD) and glutathione peroxidases (GPX). Biological parameters affecting EROD patterns (e.g. gender, ontogeny) were also investigated. Citrate synthase (CS) was used as a proxy for oxidative metabolism, responsible for basal ROS production and recruitment of antioxidant enzymes in liver cells. Hepatic OC levels were determined in individuals of different sizes (89 to 2016 g) from northern Atlantic slopes (depth range = 1000 to 1900 m). Median PCB and DDT values were 2.39 and 1.48 µg g -1 lipid weight, respectively, while median EROD activity was 15 pmol min -1 mg -1 protein. Gender greatly influenced OC levels (females were less contaminated), whilst weight (linked to ontogeny) positively affected DDT levels. EROD increased with PCB levels, and to some extent SOD and CAT were more influenced by EROD than CS, indicating that PCBs strongly affect the redox balance of roundnose grenadier liver cells through increased CYP1A activity. Therefore, OC-related CYP1A induction may be a major source of cellular ROS in liver of roundnose grenadier.

Dietary Pyridoxine Protects against Stress and Maintains Immunohaematological Status in Chanos chanos Exposed to Endosulfan

“…Therefore, the main focus of the present study was to assess the stress-mitigating role of dietary pyridoxine on endosulfan exposure of C. chanos. The exposure to organochlorine pesticides is linked with increased cytochrome P-450 (CYP) 1A1, a source of reactive oxygen species (ROS), and it is measured by 7-ethoxyresorufin-O-deethylase (EROD) activity [40,41]. Further, the activities of antioxidative enzyme (SOD and catalase) protect cells against oxygen radical damage, and the activities of phase II conjugating enzymes viz.…”

“…Further, the activities of antioxidative enzyme (SOD and catalase) protect cells against oxygen radical damage, and the activities of phase II conjugating enzymes viz. GST also increase under pesticide stress , and it helps in the conjugation of products of phase I xenobiotic metabolism. The same results have been observed in the present study as well as in our earlier work .…”

Hepatic biotransformation and antioxidant enzyme activities in Mediterranean fish from different habitat depths

“…A negative trend was revealed between CAT and EROD activities in the six compared species (r = −0.692; p N 0.05) but instead it was significantly and positively correlated to the CYP-related ECOD activity (r = 0.872; p = 0.023). In former studies a good correspondence between CAT and EROD activities was documented in deep-sea fish (Lepidion lepidion, Coryphaenoides guentheri and Bathypterois mediterraneus) in Porte et al (2000); as well as in the deep-sea macrourid Coryphaenoides rupestris (Lemaire et al, 2010) but in these reported cases, a pollution gradient was considered.…”

Molecular adaptation to high pressure in cytochrome P450 1A and aryl hydrocarbon receptor systems of the deep-sea fish Coryphaenoides armatus

“…In 1986 Stegeman et al, reported a correlation between levels of hepatic CYP1A (aka P450E) and EROD activity, and the levels of polychlorinated biphenyls in C. armatus , consistent with induction of CYP1A in this species in situ in the deep ocean [63]. Studies also suggested chemical induction of CYP1A in a congeneric though less deep-living species C. rupestris (200 – 2600 m depth) [67]. However, the extent of CYP1A increase in liver slices of C. rupestris exposed to an AHR agonist suggests that the induction response could be diminished under pressure [68].…”