Abstract: Objective To investigate the hepatotoxic effects of the plasticizer DEHP and explore its potential mechanism involving the elevation of reactive oxygen species. Methods A total of 50 Sprague-Dawley rats were randomly divided into five groups: blank control, vehicle contro, DEHP low dose( 1 mg/k), DEHP medium dose(5 mg/kg), and DEHP high dose(25 mg/kg). Body weight was monitored during the treatment period. At the end of the treatment, serum biochemical indices, liver coefficients, and oxidative/reductive indices in hepatic tissues were measured. Human normal hepatocytes HL-7702 were divided into blank control, vehicle control (DEHP 0 μmol/L) and experimental groups (DEHP 0.1 μmol/L, 10 μmol/L and 100 μmol/L). Cell viability was assessed at 24 h, 48 h and 72 h, along with measurements of TG, TC and ROS levels, and the expression of genes and proteins related to the Nrf2/HO-1 signaling. Results (1) The body weights of rats in the DEHP low dose, middle dose and high dose groups decreased in a dose-dependent manner during the 1st 2nd and 4th weeks post- treatment(P<0.05). (2) At the end of treatment, the liver weight and liver coefficient of rats in the DEHP low dose, medium dose and high dose groups increased in a dose-dependent manner compared to the vehicle control group (P<0.05). (3) Serum AST, ALT and ALP levels in the DEHP low dose, medium dose, and high dose groups were elevated in a dose-dependent manner compared to the vehicle control group at the end of the treatment period (P<0.05). (4) The levels of ROS and MDA in hepatic tissues of rats in the DEHP low dos, medium dose, and high dose groups increased in a dose-dependent manner, while the levels of SOD and GSH decreased in a dose-dependent manner at the end of treatment(P<0.05). (5) The viability of HL-7702 cells in the DEHP medium dose and high dose groups decreased in a dose-dependent manner compared to the vehicle control group at 24 h, 48 h, and 72 h post-cultivation(P<0.05), (6) The levels of TG, TC and ROS in HL-7702 cells in the DEHP medium dose and high dose groups increased in a dose-dependent manner (P<0.05). (7) The mRNA expression levels of Nrf2, HO-1 and NQO1 in HL-7702 cells decreased in a dose-dependent manner in the DEHP medium dose and high dose groups (P<0.05). (8) The protein expression levels of Nrf2, HO-1 and NQO1 in HL-7702 cells decreased in a dose-dependent manner in the DEHP medium dose and high dose groups (P<0.05). Conclusion Plasticizer DEHP exhibits hepatotoxicity, potentially through oxidative stress injury in the liver by modulating the Nrf2/HO-1 signal pathway to increase reactive oxygen species levels.

Key words: DEHP, Oxidative stress, Liver, Reactive oxygen, signal pathway of Nrf2/HO-1