Effects of Glyphosate on Zebrafish (Danio rerio) Developmental Toxicity.

Abstract

Glyphosate has been widely used in agricultural production as a highly effective, low-toxic, broad-spectrum organophosphorus herbicide. However, there has been controversy about whether it is toxic to the nervous system. In order to explore this issue in depth, the present study analyzed the molecular mechanism of action of glyphosate from four perspectives, namely, gene regulation, protein expression, morphological changes, and behavioral changes, and assessed the potential effects of glyphosate on the development of the nervous system of zebrafish through the establishment of a zebrafish model. The results showed that zebrafish embryos at 6 hpf after fertilization were exposed to glyphosate until 72 and 120 hpf. After exposure, it was found that the central nervous development-related gene Elavl3 was down-regulated, and GAP-43, Neurog1, and GFAP were up-regulated. The expression of HuC protein, which is used to maintain neuronal axonal homeostasis, was significantly reduced, and the expression of GFAP protein, which is used to repair neurological damage and inflammation, was significantly increased. Under the regulation of related genes and proteins, zebrafish larvae show abnormal changes during the development of a series of nervous systems such as heart rate slowing, somite shortening, spinal and brain malformations. At the same time, the zebrafish's action behavior also changed, with a significant decrease in its total time share in the low-speed shift and high-speed shift states, and a delayed response to dark-light environmental stimuli. In summary, studies have shown that glyphosate exposure may induce damage and inflammation of the zebrafish nervous system, resulting in developmental malformations, abnormal motor behavior, and potential neurotoxicity. Therefore, the possible neurotoxicity and environmental risks of glyphosate to aquatic animals should not be ignored and should be of great concern.