Nevin Üner

Effects of diazinon on acetylcholinesterase activity and lipid peroxidation in the brain of Oreochromis niloticus

The aim of this study was to investigate the effects of organophosphorus (OP) pesticide diazinon on acetylcholinesterase (AChE: EC 3.1.1.7) activity and its relationship to lipid peroxidation (LPO) in the brain of a freshwater fish, Oreochromis niloticus. Malondialdehyde (MDA) content was used as biomarker for LPO. Fish were exposed to 1 and 2mg/L sublethal concentrations of diazinon for 1, 7, 15 and 30 days. In the entire experimental group, AChE activity in brain significantly decreased (up to 93% of control), whereas MDA content decreased after 1 day, and increased after 7 and 15 days of exposures. MDA was in similar level with the control group after diazinon exposure of 30 days. The findings of the present study show that diazinon inhibited AChE activity and it has LPO-inducing potential in fish. The inhibition of AChE activity in the brain of O. niloticus correlated with increased MDA levels after 7 and 15 days diazinon exposures (r=-0.661, P<0.019; r=-0.652, P<0.022, respectively).

Combined effects of 2,4-D and azinphosmethyl on antioxidant enzymes and lipid peroxidation in liver of Oreochromis niloticus

This study aims to investigate the effects of the herbicide 2,4-D and the insecticide azinphosmethyl on hepatic antioxidant enzyme activities and lipid peroxidation in tilapia. Fish were exposed to 27 ppm 2,4-D, 0.03 ppm azinphosmethyl and to a mixture of both for 24, 48, 72 and 96 h. Activities of catalase (EC 1.11.1.6), glutathione-S-transferase (GST, EC 2.5.1.18) and the level of malondialdehyde (MDA) in the liver of Oreochromis niloticus exposed to 2,4-D and azinphosmethyl, both individually and in combination, were not affected by the pesticide exposures. However, glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) and glutathione reductase (GR, EC 1.6.4.2) activities in individual and combined treatments, increased significantly compared to controls. Furthermore, glutathione peroxidase (GPx, EC 1.11.1.9) activity increased in individual treatment, while the same enzyme activity decreased in combination. 2,4-D did not affect the activity of superoxide dismutase (SOD, EC 1.15.1.1), but the activity of this enzyme in azinphosmethyl treatment decreased, while its activity increased in combination. Combined treatment of the pesticides exerted synergistic effects in the activity of SOD, while antagonistic effects were found in the activities of G6PD, GPx, GR. The results indicate that O. niloticus resisted oxidative stress by antioxidant mechanisms and prevented increases in lipid peroxidation.

Oxidative stress-related and ATPase effects of etoxazole in different tissues of Oreochromisniloticus

The aim of this study is to evaluate the effects of etoxazole, a new organofluorine acaricide-insecticide, on antioxidant enzyme activities, malondialdehyde content, and different adenosine triphosphatase (ATPase) activities in the gill, kidney and muscle tissues of freshwater fish, Oreochromisniloticus. Superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), Na(+), K(+)adenosine triphosphatase, Mg(2+)adenosine triphosphatase, Ca(2+)adenosine triphosphatase activities, and malondialdehyde (MDA) were measured spectrophotometrically in whole tissue homogenates of fish exposed to five different sublethal etoxazole concentrations (0.27, 0.54, 0.81, 1.08 and 1.35ppm) for 1, 7 and 15 days. Etoxazole did not cause oxidative stress. Increasing SOD activity in etoxazole-treated fish may be an important factor to restore susceptibility and to adapt to oxidative stress. Na(+), K(+)adenosine triphosphatase activities increase in gill and muscle tissues after etoxazole exposure while they reduce in kidney. Etoxazole treatment did not show significant alterations in Ca(2+) and Mg(2+)adenosine triphosphatase activities. These results suggest that etoxazole could not enhance the oxidative stress in O.niloticus. The effects of etoxazole were only observed at high concentrations and long treatment durations. Etoxazole may specifically have an effect on Na(+), K(+)adenosine triphosphatase activity, which could alter the ionic profiles of the cells in treated tissues.

Marker enzyme assesment in the liver of cyprinus carpio (L.) exposed to 2,4‐D and azinphosmethyl

The potential utility of antioxidant enzymes and lipid peroxidation as indicators of exposure to 2,4‐D and azinphosmethyl together with the toxic effects of these compounds in freshwater fish Cyprinus carpio were evaluated. Biochemical parameters were recorded spectrophotometrically in fish liver, which were exposed to a single dose of 2,4‐D and azinphosmehtyl (1/3 LC50), and their mixture at 1:1 ratio for 24, 48, 72, and 96 h. The most sensitive parameter was glutathione S‐transferase (GST) activity, which significantly increased with experimental exposures. Glucose 6‐phosphate dehydrogenase activity did not change after 24 and 48 h while there was an elevation after 72 h in all exposure groups. The activity decreased only when these were applied in combination at 96 h. Superoxide dismutase activity increased after azinphosmethyl exposure for 48 and 96 h. 2,4‐D decreased the activity after 24 h while the activity remained at the same level with control after 48 h. An elevation was found between 72 and 96 h. Mixture treatment did not changed the activity. Glutathione reductase and catalase enzyme activities, and malondialdehyde levels remained constant in all the treatment groups compared with controls. These results suggest that induction of GST activity may be used as biomarker for the assesment of water pollution in C. carpio.

Oxidative and apoptotic effects of lambda-cyhalothrin modulated by piperonyl butoxide in the liver of Oreochromis niloticus.

The aim of this study was to investigate the toxic effects of pyrethroid pesticide lambda-cyhalothrin in the presence of piperonyl butoxide as a modulator in the liver of juvenile Oreochromis niloticus. LC(50) (96h) value of lambda-cyhalothrin was determined as 2.901μg/L for O. niloticus. The fish were exposed to 0.48μg/L (1/6 of the 96-h LC(50)) lambda-cyhalothrin and 10μg/L piperonyl butoxide for 96-h and 15-d. tGSH, GSH, GSSG, Hsp70 and TBARS contents, GPx, GR, GST and caspase-3 enzymes activities were determined. Lambda-cyhalothrin caused increases in tGSH, GSH, TBARS contents, and GST activity. Piperonyl butoxide treatment with lambda-cyhalothrin caused significant increases in tGSH GSH, Hsp70, TBARS contents, and GPx and GST activities while caspase-3 activity was decreased. The results of the present study revealed that lambda-cyhalothrin caused oxidative stress which upregulated GSH and GSH-related enzymes. Piperonyl butoxide increased the oxidative stress potential and apoptotic effects of lambda-cyhalothrin.

Sublethal Effects of Organophosphate Diazinon on the Brain of Cyprinus Carpio

Effects of diazinon, at different concentrations and exposure times, were investigated in freshwater fish, Cyprinus carpio, to elucidate the possible mode of action on lipid peroxidation together with the inhibitory effect of diazinon on acetylcholinesterase activity and changes in tissue protein levels. Cholinesterase inhibition is considered to be a specific biomarker of exposure to organophosphorus pesticides. Fish were exposed to 0.0036 μg/L, 0.018 μg/L, and 0.036 μg/L (sublethal) concentrations of diazinon for 5, 15, and 30 days, and biochemical measurements were carried out spectrophotometrically. Brain was chosen as an indicator tissue because it is a target system for the organophosphorus action. More than 20% decline in acetylcholinesterase activity relative to mean activity of the controls was observed in the diazinon-exposed groups. Protein content decreased significantly after 15 days of exposure to 0.018 μg/L and 0.036 μg/L diazinon and after 30 days of exposure to 0.036 μg/L. Malondialdehyde level declined markedly compared with the control levels. This study showed that prolonged exposures of C. carpio to diazinon had significant effects on brain acetylcholinesterase activity and that environmentally relevant concentrations of diazinon can significantly inhibit brain acetylcholinesterase activity. Altered protein content was probably due to the high energy demand under pesticide stress or inhibition of de novo enzyme synthesis. The decreased malondialdehyde content may reflect the possibility of better protection against oxidative stress.

Oxidative stress and apoptosis was induced by bio-insecticide spinosad in the liver of Oreochromis niloticus

This study was conducted to investigate acute toxic effects of spinosad on Glutathione-related oxidative stress markers, lipid peroxidation, heat shock proteins, apoptosis in the liver of Oreochromis niloticus selected as a model organism. The fish were exposed to sublethal spinosad concentrations (25, 50, 75 mg/L) for 24-48-72 h. tGSH, GSH, GSSG, and TBARS contents, GSH/GSSG ratio, and GPx, GR, GST and caspase enzyme activities were measured using spectrophotometrical methods, and Hsp70 content was measured by ELISA technique. The results demonstrated that spinosad exposure caused significant alterations in the GSH-related oxidative stress markers, and also caused increases in lipid peroxidation and stress proteins with inducing ROS generation in the liver. Apoptosis initiated with the induction of caspase-3 and Hsp70 could not protect the liver cells. Our results indicated that GSH-related antioxidant system tried to protect the liver cells from spinosad-induced hepatotoxicity however, the oxidative stress resulting from induction of ROS generation induced apoptosis in the liver of O. niloticus.

Tissue-specific effects of fenthion on glutathione metabolism modulated by NAC and BSO in Oreochromis niloticus

Introduction: The present study was designed to understand the effects of organophosphate (OP) insecticide and avicide fenthion on cellular redox status and the role of reduced glutathione (GSH) on fenthion toxicity in the liver and kidney of Oreochromis niloticus as a model organism. N-acetylcysteine (NAC) and buthionine sulfoximine (BSO) were injected intraperitoneally to fenthion-exposed fish as modulators of GSH metabolism. GSH redox status, GSH-related enzyme activities, and thiobarbituric acid reactive substances (TBARS) contents were then measured spectrophotometrically at 24, 48, and 96 hours. To assess recovery from fenthion exposure, similar analyses were performed on fish transferred to non-treated water for 24, 48, and 96 hours. Results: Fenthion increased glutathione S-transferase (GST; EC 2.5.1.18) activity and caused changes in total GSH (tGSH), GSH and oxidized glutathione (GSSG) contents and glutathione peroxidase (GPx; EC 1.11.1.9) specific activity in the liver tissue over time. Increases observed in tGSH and GSSG contents at 24 hours were decreased by fenthion treatment at 96 hours. BSO caused a sharp decline in liver tGSH, GSH, and GSSG contents and an elevation in GST and γ-glutamyl transpeptidase (γ-GT; EC 2.3.2.2) enzyme activities. A significant decrease was observed in tGSH and GSH contents and, also, GST enzyme activities in the kidney at 48-hour fenthion treatment. On the contrary to the liver, a significant increase was observed in tGSH and GSH contents in the kidney by BSO injection. NAC application eliminated the decreasing effects of fenthion on GST activity in this tissue. NAC injection caused decreases in lipid peroxidation (LPO) levels. Decline in tGSH and GSH contents were maintained in the liver during the recovery period, and elevations in LPO levels in the kidney were observed during the same period. Conclusions: In conclusion, tissue-specific and time-dependent GSH redox status disturbance of fenthion were observed. BSO revealed the significance of GST-mediated GSH conjugation on the detoxification process of fenthion. NAC seemed useful to avoid the fenthion-related oxidative toxicity.

Organic insecticide spinosad causes in vivo oxidative effects in the brain of Oreochromis niloticus

Spinosad is an organic insecticide derived from a naturally occurring soil bacterium and is used in organic farming worldwide. The aim of this study was to evaluate in vivo toxic effects of spinosad in the brain of Oreochromis niloticus as a model organism. The fish were exposed to sublethal spinosad concentrations (25, 50, 75 mg L−1) for 24–48–72 h to determine tGSH, GSH, GSSG, and TBARS contents, GSH/GSSG ratio, and GPx, GR, GST enzymes activities using spectrophotometrical methods, and Hsp70 content by an ELISA technique. Spinosad caused elevations in the contents of tGSH, GSH, GSSG, Hsp70, and reductions in the ratio of GSH/GSSG and GPx activity and an induction in the GR activity. The results indicated that spinosad had oxidative effects in the brain tissue by altering the parameters in GSH‐related antioxidant system and Hsp70. It was also suggested that spinosad‐induced free‐radicals were eliminated by GSH‐related antioxidant system in the brain of Oreochromis niloticus.

Modulation of Fenthion-Induced Oxidative Effects by BSO in the Liver of Cyprinus carpio L

The objective of the present study was to evaluate the oxidative stress potential of low-level organophosphate fenthion exposure with the modulatory effect of buthionine sulfoximine in the liver of Cyprinus carpio L. The fish were exposed to 20% of 96-hour LC50 of fenthion for 24 and 96 hours. Total and oxidized glutathione, thiobarbituric acid reactive substances, protein levels, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, superoxide dismutase, and catalase-specific enzyme activities were measured spectrophotometrically. There was a 15-day depuration period to evaluate the changes in the studied parameters. Fenthion caused a time-dependent depletion of the total and reduced glutathione levels. The oxidized/reduced glutathione ratio and catalase specific enzyme activity were reduced while the glutathione-S-transferase activity was elevated. Intraperitonal buthionine sulfoximine application disclosed the inhibitory effect of fenthion on superoxide dismutase and glutathione peroxidase activities, whereas glutathione-S-transferase activity was increased. There was no change in lipid peroxidation levels during the experiments. No amelioration was observed in the affected parameters except the glutathione-S-transferase activity in the 15-day depuration period. In conclusion, glutathione-S-transferase and catalase enzyme activities and total and reduced glutathione levels were better estimators to monitor the effects of fenthion in low concentration in the liver of C. carpio. The depuration period was not adequate to recover the antioxidant capacity.