Genotoxicity assessment and oxidative stress responses in freshwater African catfish Clarias gariepinus exposed to fenthion formulations.

Fenthion is one of the most widely used organophosphate insecticides for the control of many varieties of pests in Nigeria. The genotoxic effect of the pesticide was evaluated in the blood erythrocytes of Clarias gariepinus using the micronucleus (MN) test. The oxidative stress parameters were also studied in the liver and gill tissues. Fish were exposed to 2.0, 4.0, and 8.0 mgL-1 of fenthion and sampling was done on days 1, 7, 14, 21 and after 7-day recovery. Micronuclei induction was highest (7.55) on day 14 at all concentrations in the peripheral blood cells. Oxidative stress was evidenced by increased lipid peroxidation (LPO). Maximum LPO values of 62.47% and 71.17% were observed in the gill and liver tissues respectively in C. gariepinus exposed to 8.0 mgL-1 concentration of fenthion. There were alterations in the values of reduced glutathione (GSH), glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) during the exposure and recovery periods. The 7-day recovery period was not adequate to eliminate fenthion-induced changes as LPO, CAT, and GR activity remain elevated. However, MN frequency and activity of SOD, GSH, and GPx (except at 8.0 mgL-1) recovered. The present findings give further credence on the integrated use of MN test and oxidative stress parameters in risk assessment of pollutants in aquatic ecosystem.

Short-Term Effects of Albendazole on the Oxidative Stress Markers and Hematological Parameters in Tissues of African Catfish Clarias gariepinus.

Albendazole (ABZ) is a typical broad-spectrum benzimidazole drug used for the treatment of parasitic worm infestations in humans and animals. The present study investigated the oxidative stress biomarkers and hematological parameters in juvenile African Catfish (also known as Sharptooth Catfish) Clarias gariepinus exposed to ABZ for 96 h. Fish were exposed to 0 (control) 20, 40, and 60 mg/L ABZ. The liver and gill tissues were sampled at regular intervals of 24 h, and the results showed significant concentration- and time-dependent increases in the values of lipid peroxidation but reductions in glutathione peroxidase, catalase, superoxide dismutase, and glutathione reductase in both tissues. Erythrocytes were sampled to evaluate hematological parameters. The results showed significant concentration- and time-dependent increases in white blood cells but no significant differences in mean cellular hemoglobin. Hemoglobin values, red blood cell counts, packed cell volume, mean cell volume, and mean cellular hemoglobin concentration decreased significantly over the experimental period. The activities of lymphocytes and neutrophils increased significantly, whereas there were no significant differences in basophils, eosinophils, and monocytes among the treatment groups. Albendazole should be used with caution, as sublethal concentrations induced oxidative stress in the liver and gill tissues along with hematological changes that were more evident in liver cells. Received November 20, 2015; accepted May 4, 2015.

Subchronic Exposure to Fenthion Induces Hematological Changes in Liver Tissue of African Catfish Clarias gariepinus.

In this study, African Catfish (also known as Sharptooth Catfish) Clarias gariepinus were exposed to sublethal concentrations of fenthion of 2.0, 4.0, and 8.0 mg/L for 21 d and allowed to recover for 7 d to investigate the potential for hematological changes. Whole blood was sampled on days 1, 7, 14, and 21 postexposure and after a 7-d recovery period. During exposure, fenthion caused a reduction in red blood cell counts, hemoglobin concentration, and packed cell volume. There was an increase in white blood cell counts but no significant difference in mean corpuscular hemoglobin concentration, mean corpuscular volume, and mean corpuscular hemoglobin. Both increases and decreases were observed in white blood cell differentials. After the 7-d recovery period, both increases and decreases were observed in the hematological parameters. These results reveal that sublethal concentrations of fenthion can cause hematological alterations in African Catfish and that the substance should be used with caution. Received October 20, 2015; accepted May 4, 2016.