Histopathological Alterations in some Tissues of Heteroclarias Juveniles Exposed to Lethal and Sub-lethal Concentrations of Chlorpyrifos and Ameliorative Potentials of Vitamin E to the Toxicity of the Pesticide

Abstract

The use of pesticides on farmlands to reduce pest and increase crop yields could have detrimental effect on fish when eroded into water bodies. Histopathological effect of lethal and sub-lethal concentrations of Chlorpyrifos (CPF) on Heteroclarias juveniles  (Heterobranchus and Clarias) and the ameliorative potentials of vitamin E to the pesticide was investigated. Juveniles of Heteroclarias were assessed in a static renewal bioassay for the period of 96 h, the fish were exposed to various concentrations (0.0 ppm, 1.0 ppm, 2.0 ppm, 3.0 ppm, 4.0 ppm and 5.0 ppm), 0.24 ppm for 28 days and fed on varying concentrations (50 mg, 250 mg, 500 mg and
1000 mg) of vitamin E per kg of diet. The 96 hours LC50 values were calculated to be 2.4 ppm. During the experiments, uncoordinated behaviours such as erratic swimming and sudden quick movements were observed. At the end of the experiments, the fish were sacrificed, with the gills and liver obtained for histopathological assay. The result revealed varying types of alterations, like disruption of cartilaginous core, ruptured epithelia, epithelia necrosis, aneurysm, cellular degeneration, lamella degeneration, lamella fusion and hyperplasia in the gills of the exposed fish compared to control, while nuclear alterations, nuclear vacuolation, sinusoidal disruption, fatty degeneration, focal fibrosis and necrosis were recorded in the liver of CPF-exposed fish compared to control. However, the severity of damage reduced as the concentration of vitamin E in the diet increased except in the group fed on the highest concentration of vitamin E. The result of this study indicated that both acute and chronic concentrations of Chlorpyrifos caused various pathological alterations in Heteroclarias juveniles, but, vitamin E is capable of neutralizing the toxic effect of Chlorpyrifos and reduce the pathological lesions in Heteroclarias juveniles.

Keywords: Lethal, Sub-lethal, Chlorpyrifos, Histopathology, Heteroclarias, Vitamin E