Effect of α tocopherol and selenium on antioxidant status, lipid peroxidation and hepatopathy induced by malathion in chicks

The objective of the present study was to investigate the role of α tocopherol and selenium on malathion induced hepatic damage, and antioxidant defense in chicks. The chicks were divided into three groups. First group received malathion 10 mg/kg BW, orally for 60 days, the second group received the same dose of malathion but was supplemented with α tocopherol and selenium for 60 days and the third group served as the control. A compromised antioxidant capacity as evidenced by increased levels of erythrocytic lipid peroxidation and decreased concentration of vitamin E and decreased activity of glutathione peroxidase was observed in chicks following the administration of malathion. An improved antioxidant status was observed in chicks of second group with α tocopherol and selenium supplementation including higher concentration of vitamin E, increased activity of glutathione peroxidase and lower levels of lipid peroxidation. Histopathological studies of liver in the chicks which received malathion exhibited, moderate to severe degenerative and necrotic changes in the hepatocytes. The correlation of decreased antioxidant status of chicks with degenerative changes in liver suggests that lipid peroxidation may be one of the important mechanism in the chronic toxicity of malathion. The results indicate that α tocopherol and selenium were effective in partially alleviating degenerative changes induced by malathion in the liver of chicks by attenuating processes leading to lipid peroxidation.     

新型高效谷物保护剂“储粮安”的应用研究

选取溴氰菊酯和马拉硫磷原药为微胶囊芯料,在高速搅拌下通过界面聚合法形成微胶囊,加入稳定剂、增稠剂及载体后制成2.5%谷物保护剂储粮安,经试验散装粮应用8mg/kg、10 mg/kg和12 mg/kg及包装粮10 mg/kg、12 mg/kg,对主要储粮害虫药效维持在一年以上,达到基本无虫标准.     

Assessment of recovery of population, biomass and reproduction of the earthworm Drawida willsi following the application of malathion under field conditions

 The recovery of population, biomass and reproduction of a dominant crop field earthworm (Drawida willsi, Michaelsen) was assessed following the application of two recommended agricultural doses of malathion (2.2 mg kg^–1– single dose and 4.4 mg kg^–1– double dose) in a rice field agroecosystem for a period of 105 days. The average worm population and biomass showed 12% and 21% decline, respectively, in plots treated with single and double doses of malathion, compared with control. The peak of worm population was observed after 60 days in control (plot I) and this peak value was shifted by 15 days (i.e. observed after 75 days) in malathion-treated plots (plots II and III) indicating delay in growth and maturation of the worms following the application of malathion. Inhibition in the total number of cocoons produced, and thus in the rate of reproduction, was also observed in malathion-treated plots. The peak rate of reproduction (1.71 cocoons adult^–1) was observed after 60 days in control plots and after 75 days (1.57 and 1.40 cocoons adult^–1) in single and double dose malathion-treated plots, respectively. One-way analysis of variance showed significant differences in the population size and biomass of D. willsi up to 75 days, in rate of reproduction up to 90 days, and no difference thereafter. This indicates that, under field conditions, D. willsi worms took about 75–90 days after application of malathion to resume normal population, biomass and reproduction, and hence we suggest that a second application of malathion in single and double agricultural doses should be avoided before this time. Received: 7 September 1999     

Effect of combined exposure of commonly used organophosphate pesticides on lipid peroxidation and antioxidant enzymes in rat tissues

Organophosphate compounds are among the most widely used synthetic chemicals for controlling a wide variety of pests. Organophosphate (OP) poisoning continues to be major cause of morbidity and mortality in the third world countries. Indiscriminate use of these pesticides tends to leave residues on the objects of the environment. Present study is aimed to compare the potential of three commonly used OP pesticides, chlorpyrifos (CPF), methyl parathion (MPT) and malathion (MLT), to generate oxidative stress in rat tissues and to evaluate whether the combined exposure of these pesticides exerts synergistic or antagonistic effects. Results of the present study showed that CPF, MPT and MLT exposure to rats caused accumulation of malondialdehyde (MDA) and 4-hydroxynonanal (4HNE), the two major end products of lipid peroxidation, in liver, kidney, brain and spleen of rats. Combined exposure of these pesticides also resulted in accumulation of MDA and 4HNE in rat tissues but the increase was almost of the same order as observed in rat tissues given these pesticides singly. Exposure with CPF, MPT and MLT singly or in mixture, caused dose-dependent decrease in the activities of antioxidant enzymes namely, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx), in rat tissues when compared with control, and the decrease observed was of the same order in all the groups. Acetylcholinesterase (AChE) activity, an indicator of OP poisoning, was also decreased in rat tissues in dose-dependent manner in CPF, MPT, MLT and mixture treated group. Differential increase in the levels of cytochrome P450 (cyt P450) in hepatic and extra-hepatic tissues of rats given CPF, MPT or MLT singly or in mixture, indicate different rates of metabolism of these pesticides. Results of the present study clearly show that CPF, MPT and MLT exposure singly or in mixture, induced oxidative stress in rat tissues which may be the major contributor of the overall toxicity of the OP pesticides. Combined exposure of these pesticides does not seem to potentiate the toxicity of each other and their toxic effects are not additive.     

气相色谱法测定大米中马拉硫磷的不确定度评定

[目的]对气相色谱法测定大米中马拉硫磷的不确定度进行评定.[方法]建立了气相色谱法测定大米中马拉硫磷的测量不确定的数学模型,分析了不确定度的主要来源,对该方法所得结果的已识别来源的不确定度进行评价,并计算相对合成不确定度和相对扩展不确定度.[结果]该研究测定过程所产生的测量不确定度主要来源于回收率和重复性试验,其他因素影响很小,用该法测得大米中马拉硫磷含量为0.008 58 mg/kg,扩展不确定度为0.000 51 mg/kg(95％,k=2).[结论]该评价方法及结果对提高马拉硫磷检测数据的可靠性与准确性有一定的指导意义.     

马拉硫磷对青萍6746和油菜成花的影响

在短日植物青萍6746的光周期诱导阶段和冬性植物油菜的春化阶段外施玉米赤霉烯酮生物合成抑制剂马拉硫磷,表明其具有抑制植物成花的效应:30μmol·L~(-1)马拉硫磷完全抑制青萍6746开花,15μmol·L~(-1)马拉硫磷推迟油菜抽苔和花芽分化10d 左右。     

氯化镉、马拉硫磷和乙草胺对赤子爱胜蚓的复合急性毒性

以赤子爱胜蚓(Eisenia fetida)为试验动物, 选取氯化镉、马拉硫磷和乙草胺作为污染物, 通过人工土壤法研究了3种污染物在5种比例两种污染物复合条件下对蚯蚓的急性毒性。研究结果表明, 3种污染物在两两复合污染时的作用类型以拮抗为主, 仅在镉浓度19.46 mg·kg^-1和乙草胺175.15 mg·kg^-1 (1︰9)复合类型是相加作用, 说明复合污染生态毒理效应与污染物的化学性质和浓度水平均相关。从蚯蚓活体体重减少情况看, 在复合污染条件下, 污染物对蚯蚓生长的影响与单一污染的结果类似, 马拉硫磷对赤子爱胜蚓的影响最大, 乙草胺次之, 而氯化镉的影响最小。     

45％马拉硫磷乳油防治大豆食心虫试验

2006年进行了45％马拉硫磷乳油防治大豆食心虫试验。结果表明：45％马拉硫磷乳油对大豆食心虫具有较高的防治效果（平均防效为77．2％-86．1％）,能增加大豆产量（增产率为2．1％-3．0％）,且无药害发生。45％马拉硫磷乳油可以作为敌杀死的替代药剂在生产上使用。     

Effect of short-time malathion administration on glucose homeostasis in Wistar rat

The main objective of this study is to investigate the 24 h kinetic effect of acute administration of malathion, an organophosphorus insecticide, on glucose homeostasis in adult rats. A single dose of malathion (400 mg/kg, 1/5 of LD₅₀) was administered orally to rats, blood glucose was measured, liver and pancreas were removed to determine the level of hepatic glycogen, the activity of pancreatic acetylcholinesterase and butyrylcholinesterase, as well as the level of TBARs. Blood glucose increased in rats treated with a single dose of malathion. This effect was observed in the first hours of treatment, reached a 2.2 fold peak after 2 h, and then decreased after 4 h, followed by a decrease in the level of hepatic glycogen. The storage of glycogen starts from 6 to 12 h of administration. A decrease in cholinesterase activities was noted. The level of TBARs increased considerably in liver and pancreas. Results of this study can be explain by a stimulation of glycogenolysis and gluconeogenesis by liver, with a temporarily loss of endocrine functions of pancreas leading to hyperglycemia.