~1H NMR-based Metabolomics Approach To Study The Toxic Effects Of Herbicide Butachlor On Goldfish (Carassius Auratus)

Butachlor, is one of the most widely used herbicides in agriculture. However, large amounts of its residual in paddy fields, rivers and lakes, has caused serious water pollution. It has been reported with high ecotoxicity to aquatic plants and animals, while the toxic mechanism about butachlor on endogenous metabolites level has rarely been reported. In this study, a 1H NMR-based metabolomics approach combined with histopathological examination and biochemical assays was applied to comprehensively investigate the toxic effects of butachlor on four important organs (gill, brain, liver and kidney) of goldfish (Carassius auratus) for the first time.After 10 days’butachlor exposure at two dosages of 1 and 0.2 mg/L, fish tissues (gill, brain, liver and kidney) and serum were collected for histopathological inspection, biochemical assays and 1H NMR test. The NMR data were then further analyzed by multivariate and univariate analysis to disclose the changes of metabolites in the fish. Histopathological inspection revealed severe impairment of gill filaments and obvious cellular edema in livers and kidneys. The increase of glutathione peroxidase (GSH-Px) activity in gill and methane dicarboxylic aldehyde (MDA) level in four tissues reflected the disturbance of antioxidative system in the intoxicated goldfish. The increase of serum lactate dehydrogenase (LDH) activity and creatinine (CRE) level in butachlor exposed groups, suggested the liver and kidney injuries induced by butachlor. Orthogonal signal correction partial least-squares discriminant analysis (OSC-PLS-DA) of NMR profiles disclosed metabolic changes that were related to the toxic effects of butachlor including oxidative stress (the increased levels of choline, phosphorylcholine, glycerophosphocholine, glutathione, taurine, betaine), disorder of energy metabolism (the increase of lactate, citrate, succinate and fumarate, and the decrease of glucose, maltose, and glucose-6-phosphate) and amino acids metabolism (the increase of leucine, valine, isoleucine, tyrosine, phenlalanine, arginine), and disturbance of neurotransmitter balance (the increase of glutamate and decrease of γ-aminobutyric) in butachlor exposed goldfish. This integrated metabolomics approach provided a molecular basis underlying the toxicity of butachlor and demonstrated that metabolomics was a potent and highly effective approach to elucidate the toxicity and underlying mechanisms of herbicides and pesticides, applicable for their risk assessment.