Environmentally induced oxidative stress in aquatic animals

Molecular biomarkers of oxidative stress in aquatic organisms in relation to toxic environmental pollutants.

Oxygen in its molecular state O2, is essential for many metabolic processes that are vital to aerobic life. Aerobic organisms cannot exist without oxygen, which nevertheless is inherently dangerous to their lives. Like all aerobic organisms, fish are also susceptible to the effects of reactive oxygen and have inherent and effective antioxidant defenses that are well described in the literature. This review investigates the influence of different biotic and abiotic factors (age, phylogenetic position, feeding behavior, environmental factors, oxygen, temperature, presence of xenobiotics) on antioxidant defenses in fish. Studies of antioxidant activity in fish open a number of novel research lines providing greater knowledge of fish physiology, which will benefit various aspects of fish farming and artificial production.

Antioxidant Defenses in Fish: Biotic and Abiotic Factors

Levels of Zn, Cu, Cd, As, and Pb in the kidney, Liver, Gills and Heart of African cat fish (Clarias gariepinus) from the Ogun River in Ogun State located close to six major industries in the South Western part of Nigeria, were determined using Bulk Scientific Atomic Absorption Spectrophotometer. Fishes were also collected from Government owned fish farm in Agodi, Ibadan which was considered a reference site. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione (GSH) concentration and malondialdehyde (MDA) formation were also determined. The trend of accumulation of the metals in the organs is as follows: Heart - Zn > Cu > Pb > As > Cd; Gills - Zn > Cu > Pb > Cd > As; Kidney - Zn > Cu > Pb > As > Cd; Liver - Zn > Cu > Pb > As > Cd. The order of concentration of the metals in the organs is as follows: Arsenite - Kidney > Liver > Gills > Heart; Zinc - Gills > Liver > Kidney > Heart; Lead- Liver > Kidney > Gills > Heart; Copper- Kidney > Liver > Gills > Heart; Cadmium > Liver > Gills > Kidney > Heart. The levels of heavy metals ranged between 0.25- 8.96 ppm in the heart, 0.69- 19.05 ppm in the kidneys, 2.10-19.75 ppm in the liver and 1.95-20.35 ppm in the gills. SOD activity increased by 61% in the liver, 50% in the kidney and in the heart by 28 % while a significant decrease (44%) was observed in the gill of Clarias gariepinus from Ogun river compared to that Agodi fish farm (P<0.001). On the contrary there was 46%, 41%, 50% and 19% decrease in CAT activity in the liver, kidney, gills and heart respectively. The levels of GST activities in the liver, kidney and heart of Clarias gariepinus from Ogun river increased by 62%, 72% and 37% respectively (P<0.001) whereas there was a significant decrease (41%) in the gills (P<0.05) compared to that from the Agodi fish farm. GSH concentration increased by 81%, 83% and 53% in the liver, kidney and heart respectively but decreased by 44% in the gills. MDA levels of Clarias gariepinus were significantly (P<0.001) elevated in the liver, kidney, gills and heart by 177%, 102%, 168% and 71% respectively compared to that from Agodi fish farm. Overall, the results demonstrate that alteration in the antioxidant enzymes, glutathione system and induction of lipid peroxidation reflects the presence of heavy metals which may cause oxidative stress in the Clarias gariepinus from Ogun River. The study therefore provides a rational use of biomarkers of oxidative stress in biomonitoring of aquatic pollution.

/pdf/biomarkers-of-oxidative-stress-and-heavy-metal-levels-as-28pax1vuyh.pdf

Biomarkers of oxidative stress and heavy metal levels as indicators of environmental pollution in African cat fish (Clarias gariepinus) from Nigeria Ogun River.

Biomarkers of oxidative stress: a comparative study of river Yamuna fish Wallago attu (Bl. & Schn.).

Oxidative stress biomarkers of exposure to deltamethrin in freshwater fish, Channa punctatus Bloch

Immunomodulatory effects of fenugreek (Trigonella foenum graecum L.) extract in mice.

Effect of a single exposure of endosulfan (5 ppb) on catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), and reduced glutathione (GSH) of liver, kidney, and gill of a freshwater fish (Channa punctatus Bloch) were evaluated after 24 h of treatment. Endosulfan exposure resulted in a significant induction (p < 0.05-0.001) of GPx, GST activity, and GSH levels in all the organs. However, CAT activity was found to be significantly decreased (p < 0.01-0.001). Lipid peroxidation (LPO) values were also determined in liver, kidney, and gill and a significant increase in LPO values (p < 0.05-0.01) was observed in all the organs. We also investigated whether preexposure to low concentration of copper (10 ppb) for 4 weeks has any protective effect against endosulfan-induced oxidative damage. In copper-acclimatized endosulfan-exposed fish, a significant decrease in GPx (p < 0.001), GST (p < 0.05), GSH (p < 0.001) levels, and LPO (p < 0.01) was observed in the liver, whereas CAT activity was increased significantly (p < 0.001). However, kidney and gill did not show any significant alterations in antioxidant levels. The results of this study demonstrate that endosulfan induces peroxidative damage in liver, kidney, and gill in response to which levels of antioxidant were modulated. However, when fish preacclimatized to copper were exposed to endosulfan, protection against oxidative damage was observed only in the liver. It is proposed that measurement of antioxidants in fish tissues may prove to be useful in biomonitoring of exposure to aquatic pollutants.

Effect of endosulfan on antioxidants of freshwater fish Channa punctatus Bloch: 1. Protection against lipid peroxidation in liver by copper preexposure.

Walnut (Juglans regia L.) is extensively used in traditional systems of medicine for treatment of various ailments. It is described as an anticancer, tonic, blood purifier and detoxifier agent. The present study was undertaken to investigate modulatory effects of walnut extract on the toxicity of an anticancer drug, cyclophosphamide (CP) with special reference to protection against disruption of drug metabolizing and antioxidant enzymes. Plant extract+CP group animals showed restoration in the level of cytochrome P450 (CYP) content and in the activities of glutathione S-transferase (GST), glutathione peroxidase (GP) and catalase (CAT) in both liver and kidneys. But plant extract restored the activity of superoxide dismutase (SOD) and the level of reduced glutathione (GSH) in the kidneys only when compared with CP-treated animals. Plant extract treatment alone caused significant reduction in the content of CYP in the kidneys mainly. The extract showed a significant increase in the level of GSH and in the activities of GP in both the tissues and CAT in liver only, whereas no significant change was observed in the activities of GST and SOD. CP treatment resulted in a significant (P < 0.01) increase in the lipid peroxidation (LPO) in the liver and kidneys compared with controls, while the extract+CP treated group showed a significant decrease in the LPO in liver and kidneys when compared with the CP-treated group. The study shows that the use of J. regia extract might be helpful in abrogation of CP toxicity during the chemotherapy.

Bilal Bin-Hafeez

Papers

Biomarkers of oxidative stress: a comparative study of river Yamuna fish Wallago attu (Bl. & Schn.).

Oxidative stress biomarkers of exposure to deltamethrin in freshwater fish, Channa punctatus Bloch

Immunomodulatory effects of fenugreek (Trigonella foenum graecum L.) extract in mice.

Effect of endosulfan on antioxidants of freshwater fish Channa punctatus Bloch: 1. Protection against lipid peroxidation in liver by copper preexposure.

Aqueous extract of walnut (Juglans regia L.) protects mice against cyclophosphamide-induced biochemical toxicity.