RESUMO
@#Objective - （ ） To investigate the effects of nuclear factor erythroid 2 related factor 2 NRF2 on the oxidative stress （ ） Methods ） ，， induced by trichloromethane TCM in human normal hepatocyte L02 cells. i L02 cells were stimulated with 1 2 ， ， ， （ ）， 4 8 12 16 and 20 mmol/L TCM solution dissolved in dimethyl sulfoxide and the control group and blank group were set ， - ， up. After culturing for 24 hours the cell viability was detected by CCK 8 colorimetric method and the concentration of TCM ） -， - stimulation was screened. ii L02 cells in logarithmic growth phase were randomly divided into control group and low medium - ， ， ， and high dose groups. After 24 hours of exposure to 0 4 8 and 12 mmol/L TCM the cells were collected. The activity of （ ）， （ ）， （ - ） （ ） superoxide dismutase SOD catalase CAT glutathione peroxidase GSH Px and the level of malondialdehyde MDA NRF2， - （HO-1）， were detected by colorimetric analysis. The mRNA expression levels of heme oxygenase 1 glutamate cysteine （GCLC） （） （NQO1） - ligase catalytic subunit and NAD P H quinone dehydrogenase 1 were detected by real time fluorescence ， - ， polymerase chain reaction. The protein levels of NRF2 HO 1 GCLC and NQO1 were detected by Western blotting.Results ） ， ， ， ， i When the concentration of TCM was 4 8 12 16 and 20 mmol/L the survival rate of L02 cells decreased （ P ） ， ， significantly compared with the control group all <0.05 . The concentration of 0 4 8 and 12 mmol/L were selected as the ） ， - stimulation doses for subsequent experiments. ii Compared with the control group the activities of SOD and GSH Px in L02 （ P ） （ P ）， - cells in the three doses groups decreased all <0.05 and the levels of MAD increased all <0.05 with a dose effect - （P ）， relationship. The CAT activity of L02 cells in the medium dose group was lower than that in the control group <0.05 and the - （ P ） CAT activity of L02 cells in the high dose group was lower than that in the others three groups all <0.05 . Compared with the ， NRF2 - （P ），NRF2 control group the relative expression levels of mRNA in L02 cells in the low dose group decreased <0.05 - （P ）， NRF2 mRNA in L02 cells in the medium dose group increased <0.05 mRNA and NRF2 protein expression in L02 cells in （ P ） HO-1，GCLC， NQO1 ， the highdose group increased both <0.05 . The relative expression level of mRNA and GCLC NQO1 （ P ） protein expression in L02 cells in the three doses groups increased compared with the control group all <0.05 . The relative NRF2 - - - expression level of mRNA in L02 cells in the high dose group was higher than that in the low and medium dose groups （ P ）， - （P ）， both <0.05 and the relative expression of NRF2 protein was higher than that in the low dose group <0.05 but the HO-1 GCLC - - （ relative expression levels of and mRNA and HO 1 protein level were lower than those in the medium dose group all P ）Conclusion - <0.05 . TCM exposure can inhibit the proliferation of L02 cells by inducing oxidative stress with a dose effect ， relationship. In this process the antioxidant mechanism mediated by NRF2 was activated. The expression of antioxidant defense ， - ， and detoxification related target genes downstream of NRF2 signaling pathway was activated and the expression of HO 1 - GCLC and NQO1 was up regulated to alleviate the oxidative damage caused by TCM.