Developmental Neurotoxicity of Methamidophos in the Embryo-Larval Stages of Zebrafish

Abstract

Methamidophos is a representative organophosphate insecticide. The knowledge of its developmental neurotoxicity is limited, especially for zebrafish in the early stages of their life. Four hour post-fertilization (hpf) zebrafish embryos were exposed to several environmentally relevant concentrations of methamidophos (0, 25, and 500 μg/L) for up to 72 hpf. Locomotor behavior was then studied in the zebrafish larvae at this timepoint. Acridine orange (AO) staining was carried out in the zebrafish larvae, and the mRNA levels of genes associated with neural development (mbp and syn2a) were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The number of escape responders for mechanical stimulation was significantly decreased in exposed groups. AO staining showed noticeable signs of apoptosis mainly in the brain. In addition, the mRNA levels of mbp and syn2a were both significantly down-regulated in exposed groups. Our study provides the first evidence that methamidophos exposure can cause developmental neurotoxicity in the early stages of zebrafish life, which may be caused by the effect of methamidophos on neurodevelopmental genes and the activation of cell apoptosis in the brain.

Short- and long-term exposure to methamidophos impairs spermatogenesis in mice

“…In fact, MET has the ability to promote apoptosis. He et al [12] reported that MET treatment promoted a significant increase in apoptotic cells in the brain of zebrafish larvae. MET possesses both hydrophilic and hydrophobic domains [10], so it is reasonable to expect that this pesticide can pass through the blood-testis barrier by diffusion and cause death of the Sertoli cells.…”

“…Previous studies have shown that MET exposure may lead to developmental neurotoxicity in aquatic systems [12] and attack behavior in non-aggressive mice [13]. MET exposure has also been shown to be a factor in some reproductive disorders.…”

Degradation of Acephate and Its Intermediate Methamidophos: Mechanisms and Biochemical Pathways

“…Zebrafish is a commonly used model test organism due to its advantages of high genetic and organ system homology to humans, external fertilization, high fecundity, and transparency in early adulthood (Liu et al, 2018). It has reported that methamidophos exposure may affect neurodevelopmental genes and activate intracellular apoptosis, leading to early developmental neurodamage in zebrafish (He et al, 2017). The brain may be an important target of methamidophos toxicity in zebrafish, revealing the potential neurotoxicity of methamidophos to other aquatic species and humans (Rodríguez et al, 2012;Peng et al, 2015;He et al, 2017).…”

“…It has reported that methamidophos exposure may affect neurodevelopmental genes and activate intracellular apoptosis, leading to early developmental neurodamage in zebrafish (He et al, 2017). The brain may be an important target of methamidophos toxicity in zebrafish, revealing the potential neurotoxicity of methamidophos to other aquatic species and humans (Rodríguez et al, 2012;Peng et al, 2015;He et al, 2017). Zebrafish embryo development retardation, larval deformities, and decreased chorionic surface tension were also induced by exposure to acephate (Liu et al, 2018).…”

“…Acephate and methamidophos have both hydrophilic and hydrophobic properties that assist them easy movement between water and FIGURE 1 | The structure of acephate and methamidophos. soil (He et al, 2017). Studies have shown that methamidophos residues may decrease the total microbial biomass carbon and fungal biomass (Li et al, 2008;Wang et al, 2008).…”