Effects Of Uric Acid On Hepatocyte Oxidative Stress And Mitochondria Function

Objective: To investigate the effects of uric acid on hepatocyte oxidative stress and mitochondria function. Method: Hepatocyte was cultured and intervented with different concentrations of uric acid in vitro. Cultured hepatocytes were collected after 24, 48, 72,96 h. The morphology, cell viability and apoptosis of hepatocytes were measured by electron microscopy, MTT and flow cytometry respectively. AST and ALT, 8-OhdG,SDH, CCO and ATP, GSH-Px, SOD and MDA, which act as the index of hepatocyte function, DNA damage, mitochondrial function and oxidative stress, were detected by enzyme mark instrument. ROS was measured by DCFH-DA kit. mRNA level of SOD and GSH were measured by RT-PCR. Protein expression of SOD, GSH and γ-GCS were measured by Western blot. Results: 1. The morphology, cell viability and apoptosis:irregular shape, less surface villi, apoptosis and necrosis of cells appeared when the concentration of uric acid was 20mg/dL; With the increasment of uric acid concentration and the prolongation of time points, the cell apoptosis of hepatocyte were increased.Compared with control group, the treated hepatocytes showed high apoptosis rate when uric acid level was more than 20mg/dL and intervention time was 48~96h and 72~96h significantly(P < 0.05). 2. Hepatocyte function and DNA damage: Compared with control group, the treated hepatocytes showed higher ALT and AST when uric acid level was more than 20mg/dL and intervention time was 72~96h and higher 8-OHdG when uric acid level was 30mg/dL and intervention time was 24~96h significantly(P<0.05). 3.The oxidative stress index in hepatocyte: Compared with control group, the treated hepatocytes showed lower SOD and GSH when uric acid level was 20mg/dL and intervention time was 48~72h and higher ROS and MDA when uric acid level was more than 20mg/dL and intervention time was 96 h significantly(P<0.05). 4. mRNA level of downstream gene and protein expression of Nrf2-ARE pathway in hepatocyte: Compared with control group, the treated hepatocytes showed lower mRNA level of SOD and GSHgenes when uric acid level was more than 10mg/dL and intervention time was 48~72h and lower expression of SOD and GSH, γ-GCS when uric acid level was 30mg/dLand intervention time was 24 h and 96 h significantly(P<0.05). 5. The function of hepatocyte mitochondria: Compared with control group, the treated hepatocytes showed lower ATP,SDH and CCO when uric acid level was more than 10mg/dL and intervention time was24~72h significantly(P<0.05). Conclusion: High concentration of uric acid(more than20mg/dL) may induce the change of hepatocyte’s morphology and oxidative stress in the mitochondria. Furthermore, increased ROS and apoptosis’ s production may ultimately lead to mitochondrial damage of hepatocyte.