Assis Caio Rodrigo Dias, Amaral Ian Porto Gurgel, Castro Patrícia Fernandes, Carvalho Luiz Bezerra Júnior, Bezerra Ranilson Souza
Laboratório de Enzimologia-LABENZ, Departamento de Bioquímica, Universidade Federal de Pernambuco, Recife-PE, Brazil.
Environ Toxicol Chem. 2007 Jul;26(7):1451-3. doi: 10.1897/06-488r1.1.
Dichlorvos is an acutely toxic organophosphorous pesticide that is known as a classical acetylcholinesterase (AChE; EC 3.1.1.7) inhibitor. Here, the brain AChE from the important Amazonian fish tambaqui (Colossoma macropomum) was assayed in the presence of this insecticide and also of deltamethrin, a classical sodium and potassium channel inhibitor (negative control). Four tissue homogenates were analyzed in triplicate for AChE activity using acetylthiocholine as the substrate and 5,5'-dithiobis(2-nitrobenzoic) acid (DTNB) as the color-developing agent. Each tissue homogenate represented pooled brains from five fish. The inhibitory effect of dichlorvos on AChE activities was determined at concentrations from 0.001 to 10 ppm and compared to controls. This effect followed an exponential decay model (y = 9.420 + 26.192e(-x/5.380); r2 = 0.989), presenting IC50 (the concentration of dichlorvos that is required for 50% of AChE inhibition) of 0.081 ppm (0.368 micromol/L). No effect was observed for the deltamethrin, and the concentration 0.0452 micromol/L of dichlorvos was significantly different from this control. These results suggest that tambaqui brain AChE can be proposed as a biomarker for dichlorvos and can be used as a tool for aquatic environment monitoring.
敌敌畏是一种剧毒有机磷农药，是一种典型的乙酰胆碱酯酶（AChE；EC 3.1.1.7）抑制剂。在此，在这种杀虫剂以及溴氰菊酯（一种典型的钠钾通道抑制剂，作为阴性对照）存在的情况下，对重要的亚马逊鱼类 tambaqui（大盖巨脂鲤）的脑 AChE 进行了测定。使用乙酰硫代胆碱作为底物，5,5'-二硫代双（2-硝基苯甲酸）（DTNB）作为显色剂，对四种组织匀浆进行了三次重复分析以测定 AChE 活性。每种组织匀浆代表来自五条鱼的合并脑。在 0.001 至 10 ppm 的浓度下测定了敌敌畏对 AChE 活性的抑制作用，并与对照进行了比较。这种作用遵循指数衰减模型（y = 9.420 + 26.192e(-x/5.380)；r2 = 0.989），呈现出 0.081 ppm（0.368 μmol/L）的 IC50（使 AChE 抑制 50%所需的敌敌畏浓度）。未观察到溴氰菊酯有作用，并且 0.0452 μmol/L 的敌敌畏浓度与该对照有显著差异。这些结果表明，tambaqui 脑 AChE 可被提议作为敌敌畏的生物标志物，并可作为水生环境监测的工具。
