Regulation of arcuate genes by developmental exposures to endocrine-disrupting compounds in female rats.

Developmental exposure to endocrine-disrupting compounds (EDCs) alters reproduction and energy homeostasis, both of which are regulated by the arcuate nucleus (ARC). Little is known about the effects of EDC on ARC gene expression. In Experiment #1, pregnant dams were treated with either two doses of bisphenol A (BPA) or oil from embryonic day (E)18-21. Neonates were injected from postnatal day (PND)0-7. Vaginal opening, body weights, and ARC gene expression were measured. Chrm3 (muscarinic receptor 3) and Adipor1 (adiponectin receptor 1) were decreased by BPA. Bdnf (brain-derived neurotropic factor), Igf1 (insulin-like growth factor 1), Htr2c (5-hydroxytryptamine receptor), and Cck2r (cholescystokinin 2 receptor) were impacted. In Experiment #2, females were exposed to BPA, diethylstilbestrol (DES), di(2-ethylhexyl)phthalate, or methoxychlor (MXC) during E11-PND7. MXC and DES advanced the age of vaginal opening and ARC gene expression was impacted. These data indicate that EDCs alter ARC genes involved in reproduction and energy homeostasis in females.

Oxidative stress responses and recovery patterns in the liver of Oreochromis niloticus exposed to chlorpyrifos-ethyl.

Chlorpyrifos is the most common insecticide in freshwater ecosystems, and detected in agricultural and fishery product. In this study, Oreochromis niloticus were exposed to 5, 10 and 15 ppb sublethal concentrations of chlorpyrifos in order to determine the oxidative stress response in liver. Acetylcholinesterase (AChE) activity was significantly inhibited. Superoxide dismutase activity (SOD) increased after 15 days of chlorpyrifos treatments at all concentrations (146.95%, 53.04%, 208.70%, respectively). Malondialdehyde levels were higher than that of the control level after 15 days of 5 ppb (95.65%), 10 ppb (69.56%) and 15 ppb (252.17%) chlorpyrifos treatments. Malondialdehyde levels were also increased ranging from 59.09%, 113.63% to 195.46% after 30 days of 5, 10 and 15 ppb chlorpyrifos exposures. Glutathione S-transferase activity decreased except for 15 days low concentration exposure. Catalase (CAT) activity decreased while there is no significant alteration in glutathione peroxidase activity. After recovery period, the low concentration group of chlorpyrifos provided a protection in AChE activity during recovery, but fish were observed to be unable to overcome the inhibition of AChE activity at high concentration groups. CAT activity remained reduced, SOD activity increased whereas the other biochemical parameters recovered to control levels. Results of this study suggest that chlorpyrifos induces oxidative stress in the liver of O. niloticus and this effect is not related with anti-acetylcholinesterase activity of pesticide.

Effects of diazinon on antioxidant defense system and lipid peroxidation in the liver of Cyprinus carpio (L.).

Diazinon is a widely used organophosphorus pesticide in agriculture and environmental health, hence its adverse effects on nontarget animals, especially on fish is to be determined. The present study therefore aimed at detecting the biochemical changes caused by diazinon. To accomplish this aim, we studied the effects of sublethal concentrations (0.0036, 0.018, and 0.036 ppb) of diazinon on acetylcholine esterase activity, antioxidant enzyme activities, and lipid peroxidation in the liver of Cyprinus carpio on days 5, 15, and 30 after the exposure. The results revealed that the antioxidant enzyme activities such as superoxide dismutase, glutathione peroxidase, and catalase were induced by diazinon exposure. In addition, the highest catalytic activity of glutathione S-transferase (GST) was obtained with 1-chloro-2, 4-dinitrobenzene (CDNB). GST activity toward 1,2-dichloro-4-nitrobenzene (DCNB) was also observed in the liver, yet it was relatively low as opposed to the other substrates tested. On the other hand, hepatic malondialdehyde level did not show any significant alteration except after the exposure on day 15. The exposure of low concentrations of diazinon to C. carpio can induce oxidative stress in liver; yet restoring susceptibility and adapting to oxidative stress are likely to occur when low level of oxidative stress is administered. Furthermore, no significant change was observed in hepatic lipid peroxidation after diazinon treatment indicating that liver tissue resisted to oxidative stress by enhancing their antioxidant mechanisms. The level of lipid peroxidation was assumed to be associated with the concentrations of diazinon and experimentation periods. The induction of glutathione S-transferase and antioxidant enzyme activities were also assumed to have resulted from the defense against the toxicity of diazinon.

Evaluation of oxidative stress responses and neurotoxicity potential of diazinon in different tissues of Cyprinus carpio.

Toxicity of organophosphorus insecticides is mainly due to the inhibition of acetylcholinesterase, but, oxidative stress may be involved in the toxicity of this pesticides. Therefore, it was investigated whether diazinon, a commonly used organophosphate, may induce oxidative stress and cholinesterase inhibition in different tissues of Cyprinus carpio. Sublethal concentrations of diazinon (0.0036, 0.018 and 0.036ppb) were administired to C. carpio L. for 5, 15 and 30 days. The study was made by measuring biochemical stress responses of C. carpio L. spectrophotometrically taking into account acetylcholinesterase (AChE), Na(+)K(+)-adenosine triphosphatase (Na(+)K(+)-ATPase) and other antioxidant enzyme activities, as well as malondialdehyde and protein contents in gill, muscle and kidney tissues of the fish. Results of the study suggest that AChE (in gill and muscle tissues) and Na(+)K(+)-ATPase (in muscle and kidney tissues) activities decreased; that antioxidant enzymes, in particular superoxide dismutase (SOD), increased in gill, kidney and muscle tissues. We also observed the existence of a protective function of antioxidant enzymes against lipid peroxidation in muscle tissue. The changes in MDA content varied between increases and decreases in kidney tissue. In gill tissue, however, lipid peroxidation could not be prevented despite induction of SOD and glutathione peroxidase activities. We could see that the protein content decreased only in gill tissue as diazinon dosage was gradually increased until the 15th day of the experiment. During the period between 15th and the 30th days, the protein level in the fish was observed to have reached to that of the control group. This change in protein level can be attributed to adjustment of the fish to its new environmental conditions. Considering most of the parameters in tissues, it can be stated that diazinon exerted its effect at low concentration and during a long period of time, and its toxicity increased dose dependently. This study reveals that C. carpio developed tissue-specific adaptive response to neutralize the oxidative stress following pesticide exposure depending on different antioxidant levels in tissues and that SOD can be used as a biomarker in determining diazinon toxicity due to its early response at even low concentration levels.

Neurotoxicity evaluation of the organofluorine pesticide etoxazole in the brain of Oreochromis niloticus.

Etoxazole is a new organofluorine pesticide that has been used worldwide as acaricide and insecticide since 1998. Almost no previous attempt has been made to evaluate the toxic effects of etoxazole in vertebrates. Using fish (Oreochromis niloticus) as a suitable model organism, the aim of this study was to indicate whether etoxazole affects acetylcholinesterase and sodium potassium-activated adenosine triphosphatase activities in the brain tissue in order to evaluate the impacts on neurotoxicity and ion transportation. Enzyme activities were determined using spectrophotometric methods. At the sublethal concentrations (0.27, 0.54, 0.81, 1.08, 1.35 mg/L) and exposure durations (1, 7, 15 days) tested, etoxazole has no inhibitory effect on the brain acetylcholinesterase and sodium potassium-activated adenosine triphosphatase activities. Our results suggest that etoxazole and/or its metabolites may not reach or penetrate the blood-brain barrier; therefore, they do not essentially alter the functions of these two important enzymes for the brain.

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).

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 assessment 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 LC(50)), 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 assessment of water pollution in C. carpio.