Abstract

In the late twentieth century, tremendous use of second-class organophosphate insecticides especially chlorpyrifos (CPF) resulting into heavy accumulation in different non-targeted aquatic species including fishes leads to apparent structural and biochemical changes in different organs and related abnormal behavioral responses. The present study has been undertaken as a pioneer attempt to assess the toxic effects of CPF on histopathological changes in pseudobranchial neurosecretory cells (PNSCs) of a neuroendocrine system of gill region, optic tectum (OT) and cerebellum, biochemical changes (acetylcholinesterase (AChE) activity and antioxidant markers) in the brain and associated locomotory behavioral alterations in air-breathing catfish, Heteropneustes fossilis. The fishes were exposed to CPF concentration of 1.92 mg/l for four days and their locomotor activities were recorded by ANY-MAZE software (Stoelting, Kiel, WI), an automated behavior tracking device. The acute exposure of CPF induced pathological changes in PNSCs, subtle changes in granular cells of the cerebellum and neuroarchitectural pattern of different layers of OT as compared to control. In the CPF exposed brain, AChE activity was significantly decreased while antioxidant enzymatic activity such as SOD activity was increased but CAT activity was substantially decreased. The CPF exposed fishes displayed significantly reduced locomotory activities with symptoms of motionless, loss of equilibrium and erratic movements. This study concludes that acute exposure to CPF for short duration may induce dys-regulation of neurosecretory activity of PNSCs, altered biochemical activity of brain and reduced locomotory/swimming performances in fishes.

摘要

20世纪后期，二类有机磷杀虫剂特别是毒死蜱（CPF）的大量使用，导致包括鱼类在内的不同非靶向水生物种大量积累，导致不同器官的结构和生化发生明显变化，并产生相关的异常行为反应。本研究已作为先驱尝试评估 CPF 对鳃区、视顶盖 (OT) 和小脑神经内分泌系统的假鳃神经分泌细胞 (PNSC) 的组织病理学变化、生化变化 (乙酰胆碱酯酶 (AChE)活性和抗氧化标志物）在呼吸空气的鲶鱼（Heteropneustes化石）中的大脑和相关的运动行为改变. 将这些鱼暴露于 1.92 mg/l 的 CPF 浓度 4 天，并通过自动行为跟踪设备 ANY-MAZE 软件（Stoelting，Kiel，WI）记录它们的运动活动。与对照相比，CPF 的急性暴露引起 PNSCs 的病理变化、小脑颗粒细胞的细微变化和 OT 不同层的神经结构模式。在暴露于CPF的大脑中，AChE活性显着降低，而SOD活性等抗氧化酶活性增加，但CAT活性显着降低。暴露于 CPF 的鱼的运动活动显着减少，表现为一动不动、失去平衡和不稳定运动的症状。