Toxic Effect Of Isocarbophos Pesticide On Chinese Lizards (Eremias Argus ) Following Oral Administration

Widespread use of agrochemicals has played an significant role in the improvement of agricultural production efficiency.But at the same time,the abuse of agrochemicals also pollutes the ecological environment.During the use of pesticides,there is only actually 10% being used to control pests,germs and weeds.And 90% of them flow into the environment through various channels,causing some pollutions to the atmosphere,water and the soil that ultimately risk to human health.Organic contaminants will eventually harm to our living environment by evaporation,rainfall and the surface run-off.The assessment of the toxic effects of drugs and environmental pollutants in the laboratory often uses mammals or aquatic organisms as model organisms,but ignoring the research on reptiles.Eremias argus are widely distributed in China.So they are potential for our models in experiments.Organophosphorus pesticides are persistent organic contaminants.Even if isocarbophos has been banned in many crops,but it still can be detected in various environmental matrix.Their hazards are complex and long-term.It is imperative for the use of isocarbophos for crops such as grains,cotton,forest trees,pastures and so on,so it is important to evaluate this pesticide on the sensitive organisms in the soil.Two aspects were conducted in this experiment:1.According to the “OECD up and down procedure”,the oral acute toxicity assessment of isocarbophos on male Eremias argus was carried out.The pesticide was dissolved in corn oil and diluted to certain concentrations,and administrated by a single oral exposure.The acute neurotoxicity symptoms was assessed by appearance and exercise behavior.Then,based on the number of dead lizards at 14 days,the maximum likelihood method was conducted to estimate the oral acute toxicity,LD50 value of isocarbophos on male Eremias argus is 3.66 mg/kg.2.Sub-chronic toxicity assessment of isocarbophos was based on the acute toxicity and was conducted to assess the toxic effects of the pesticide after consecutive exposure for 14 days.Eventually,toxicological assessments were performed on the following indicators: neurotoxic target enzymes,antioxidant enzymes,energy metabolizing enzymes and histopathological lesions.A number of biochemical indexes of lizards' organs:catalase(CAT),superoxide-dismutase(SOD),malondialdehyde(MD A),acetylcholinesterae(ACh E)and Na~+K~+-ATPase were assessed.The results shows that the activities of CAT in all organs except the lungs were decreased.The activities of SOD were significantly reduced in the livers,gonads and kidneys.MDA is mainly increased in the livers and gonads,so that the products of lipid peroxidation reaction malondialdehyde accumulated in the livers and gonads.In the brain tissues,the activities of ACh E decreased first and then increased with the extended exposure time.The Na~+K~+-ATPase activity in the brain tissues and gonads was also significantly reduced.That meat isocarbophos inhibited the activities of ACh E and Na~+K~+-ATPase and caused neurotoxicity and might have a certain degree of influence on the reproductive system of lizards.In addition,histopathological assessments were performed on the tissues of lizards.It was found that the liver,kidney and the testes were all significantly damaged after exposure of isocarbophos.Our study shows that isocarbophos can produce neurotoxicity and reproductive toxicity dramatically.