Neurotoxicity and related mechanisms of flame retardant TCEP exposure in mice

Objective: To explore the neurotoxicity and mechanism of tris(2-chloroethyl) phosphate (TCEP) exposure in mice.Methods: Total 30 adult Kunming mice were randomly divided into normal control group (0 mg/kg·d), low-dose TCEP group (10 mg/kg·d), and high-dose TCEP group (100 mg/kg·d), and administered continuously by gavage for 30 days.Results: Compared with the control group, the water intake of high-dose TCEP group was declined significantly (p < 0.05), and the organ index of liver and spleen were increased significantly (p < 0.05). In addition, the escape latency of TCEP exposed mice were longer than that in the control group in water maze test (p < 0.05), while the total swimming course of high-dose TCEP group was elevated and the swimming time in target quadrant was obviously shortened compared with the control group (p < 0.05). The serum levels of total-triiodothyronine (TT3) and free triiodothyronine (FT3) were significantly higher in the high-dose TCEP group than in the control group (p＜0.05). Compared with the control group, the activities of glutathione transferase (GST) and super oxide dismutase (SOD) in the high-dose TCEP group were increased, and GST in the low-dose TCEP group were decreased, while the content of malonaldehyde (MDA) in both groups was increased (p＜0.05). In the CCK8 assay, the viability of PC12 cells decreased with an increase of TCEP concentration, indicating a concentration dependent neurotoxicity.Conclusion: TCEP exposure can cause neurotoxicity by increasing thyroid hormones and inducing oxidative damage in mice.