Toxicity bioassay and sub-lethal effects of diazinon on blood profile and histology of liver, gills and kidney of catfish, Clarias gariepinus

Abstract The catfish, Clarias gariepinus, was exposed to different acute concentrations (5-10 mg/l) of diazinon and the Lc50 value was recorded as high as 7.3 mg/l for 96 hours. The fishes exposed to three sub-lethal levels of diazinon (0.73, 1.095 and 1.46 mg/l) for 30 days showed that the pesticide induces changes in different blood parameters. Number of red blood cells (RBC), haemoglobin level and haematocrit values were elevated whereas white blood cells (WBC) count was reduced. Various blood indices like mean corpuscular volume (MCV), mean corpuscular haemoglobine (MCH) and mean corpuscular haemoglobine concentration (MCHC) vary insignificantly in the fish treated with diazinon. Glucose level and activity level of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was increased in Clarias gariepinus exposed to diazinon. Protein level in plasma of fish treated with pesticide was changed but the change was insignificant. Histological changes in the liver, gills and kidney of fishes exposed to diazinon were apparent when compared to control. Hepatocytes necrosis and bleeding were more distinct in the fishes exposed to pesticide. Glomerulus hypertrophy and bleeding in kidneys; and fusion and degeneration of secondary lamellae and epithelial hyperplasia in gills were also observed in the exposed fish.

摘要 本研究将革胡子鲶（Clarias gariepinus）暴露于不同急性浓度（5~10 mg/L）的二嗪农中，测得其96小时半数致死浓度（LC50）高达7.3 mg/L。将该鲶鱼分别暴露于0.73、1.095及1.46 mg/L三个二嗪农亚致死浓度下30天后，结果显示该农药可引发鱼类多项血液生理指标发生变化：红细胞（RBC）计数、血红蛋白水平及血细胞比容值均显著升高，而白细胞（WBC）计数则出现降低。二嗪农处理组鱼类的各项血液指数，如平均红细胞体积（MCV）、平均红细胞血红蛋白（MCH）及平均红细胞血红蛋白浓度（MCHC）均无显著变化。暴露于二嗪农的革胡子鲶体内血糖水平，以及天冬氨酸转氨酶（AST）、丙氨酸转氨酶（ALT）的活性均有所升高。经该农药处理的鱼类血浆蛋白水平虽有改变，但差异不显著。与对照组相比，暴露于二嗪农的鱼类肝脏、鳃及肾脏的组织学变化较为明显：肝细胞坏死与出血现象在给药组鱼类中更为显著；肾脏组织可见肾小球肥大与出血；鳃组织则出现次级鳃丝融合变性及上皮增生现象。