Chronic exposure to trace chromium induces oxidative stress in mouse liver cells

Objective To explore the effects of chronic exposure to trace chromium(VI) as a result of metal-on-metal hip arthroplasty on oxidative stress in mouse liver cells.Methods Eighty NIH mice were randomly divided into 4 groups and subject to intraperitoneal injection of CrO3 at the dose of 0,5,10 or 20 mg/kg every other day for 16 weeks.Five mice from each group were selected every 4 weeks for determining the content of chromium(VI) in the whole blood and the levels of reactive oxygen species(ROS),malondialdehyde(MDA),eglutathione(GSH),glutathione reductase(GR) activity,and glutamate cysteine ligase(GCL) expression in the liver cells.The ultrastructural changes of the liver cells were also observed using transmission electron microscopy.Results Exposure to 5 and 10 mg/kg CrO3 caused significantly increased blood chromium concentration and ROS level,which reached the peak level at 8 weeks and became stabilized,whereas at the dose of 20 mg/kg,CrO3 exposure resulted in progressive,time-dependent increase of blood chromium concentration and ROS level.MDA showed no significant changes in the 4 groups.With the prolongation of the exposure time,GSH content and GR activity were decreased in these groups.In 5 and 10 mg/kg CrO3 groups,GCL expression increased at each time point of measurement,but in 20 mg/kg group,GCL expression decreased gradually with a prolonged exposure.Transmission electron microscopy revealed apoptotic changes of the liver cells in 20 mg/kg group.Conclusion The slow accumulation of trace chromium(VI) after metal-on-metal hip arthroplasty may cause oxidative stress and changes in the oxidative stress system in the liver cells.