Abstract: Objective To observe the effects of lead exposure through drinking water on the expression of XRCC1 mRNA in cerebral cortex, cerebellum and hippocampus of rats and its relationship with oxidative stress. Methods Forty SD rats were divided randomly into five groups: control group and four exposure groups (100 mg/L, 200 mg/L, 400 mg/L and 800 mg/L lead acetate for 60 days respectively). The expression of XRCC1 mRNA in brain was detected by RT-PCR technique after separation of cerebral cortex, cerebellum, and hippocampus. At the same time, lead content in brain tissue and catalase (CAT), glutathione (GSH) and hydrogen peroxide (H2O2) were also detected. Results Compared with control group, the expression of XRCC1 mRNA, content of lead and H2O2 levels were significantly higher in cerebral cortex, cerebellum and hippocampus of exposure groups (P < 0.05), whereas the contents of CAT and GSH were significantly lower (P < 0.05). There was a positive correlation between lead level and the expression of XRCC1 mRNA in cerebral cortex, cerebellum and hippocampus of exposure groups (r=0.608, 0.438 and 0.470， P＜0.01). There was a negative correlation between the lead level and CAT and GSH (r=-0.343, -0.465、 -0.423, -0.383, -0.489 and -0.366， P＜0.05). A positive relationship was found between the lead level and H2O2 (r=0.455, 0.517 and 0.342， P＜0.05). Conclusion Lead exposure can affect the expression of mRNA gene in XRCC1 through inducing cell oxidative stress.

Key words: lead, XRCC1, oxidative stress, catalase, glutathione, hydrogen peroxide, brain tissue