Effects of Clothianidin on Biochemical Parameters of Adult Zebrafish

The ubiquitous use of insecticides leads to detrimental effects on non-target organisms due to accidental exposure. Neonicotinoid insecticides are popularly used worldwide for their high affinity for arthropod nicotinic receptors which effectively kill insect pests. Low affinity towards vertebrate nicotinic receptors, make them safer as compared to traditional insecticides. Recent studies demonstrated that neonicotinoid exposure can cause some toxicity in vertebrates including humans. Zebrafish is one of the popular model organisms to study ecotoxicity. This is the first study on adult zebrafish to report the effect of novel neonicotinoid, Clothianidin on mortality, liver antioxidant stress profile, liver function profile and brain acetylcholinesterase (AChE). Observations were made over two treatment periods, 96 hours, and 21 days, in five groups exposed to varying concentrations of Clothianidin viz. 30mg/L, 50mg/L, 70mg/L, 90mg/L, 110mg/L and a control. Although no mortality was observed, Clothianidin exposure led to increased activity of superoxide dismutase (SOD) enzyme, lipid peroxidation and decreased catalase (CAT), glutathione-S-transferase (GST). Treated groups also showed increased concentrations of liver enzyme alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and acid phosphatase (ACP). These results indicate that Clothianidin causes disturbances in the hepatic function. A prominent decreasing trend observed in brain AChE shows that Clothianidin inhibits AChE in adult zebrafish. Further investigations on DNA damage and gene expression studies could be conducted to understand the exact mechanism of action of Clothianidin