Transcriptomics and metabolomics reveal Ca overload and osmotic imbalance-induced neurotoxicity in earthworms (Eisenia fetida) under tri-n-butyl phosphate exposure.

Tri-n-butyl phosphate (TNBP) is mass-produced and widely utilized in many products, which has increasingly drawn concern about its potential environmental risks. However, little is known about the toxic mechanism on soil-dwelling organisms caused by TNBP. In this study, earthworms (Eisenia fetida) were exposed to environmentally relevant or higher concentrations of TNBP (0, 0.1, 1, and 10 mg/kg) in artificial soil for 14 days. Our results showed that TNBP accumulated in earthworm nervous tissue (cerebral ganglions). In addition, the content of glutamate in cerebral ganglions decreased compared to the control (p < 0.05). The concentration of Ca in earthworm cerebral ganglions increased. However, both Na/K-ATPase and Ca-ATPase activities were significantly reduced compared to the control (p < 0.05), which led to neurotoxicity in earthworm nervous tissue. Furthermore, the transcriptome and metabolomics revealed the toxic mechanism in earthworm nervous tissue caused by TNBP. Results indicated that the main neurotoxicity mechanisms induced by TNBP were an osmotic imbalance and Ca overload in cerebral ganglions. Our findings fill a gap in the literature on neurotoxicity mechanisms of earthworm response to TNBP exposure and contribute to a better understanding of the adverse effects of TNBP on soil-dwelling organisms in terrestrial ecological systems.