Objective To evaluate the effect of dexmedetomidine on the expression of 8-Oxoguanine DNA glycosylase 1 (OGG1) mRNA in rat hippocampal neurons subjected to oxygen-glucose deprivation/reoxygenation and restoration (OGD/R).Methods Hippocampal neurons isolated from pathogen-free neonatal Sprague-Dawley rats born within 3 days,were cultured primarily and seeded in 96-well plates (100 μl/well) or 6-well plates (2 ml/well) at the density of 1 × 106 cells/ml.The cells were randomly divided into 5 groups (n=30 each):control group (group C),group OGD/R,and different concentrations of dexmedetomidine groups (DEX1-3 groups).The cells were cultured in normal culture medium in group C and the cells were subjected to OGD/R in the other groups.In DEX1-3 groups,dexmedetomidine with the final concentrations of 0.1,1.0 and 10.0μmol/L were added,respetively,at 2h before OGD.At 24h of restoration,hippocampal neurons were stained with haematoxylin and eosin (H.E) for examination of pathological changes,the cell survival rate was detected by MTT method,the activity of superoxide dismutase (SOD) and content of malondialdehyde (MDA) were detected by colorimetric method,and the expression of OGG1 mRNA was detected by RT-PCR.Results The pathological changes of neurons were obvious in group OGD/R,and the pathological changes of neurons were significantly mitigated in DEX1,DEX2 and DEX3 groups.Compared with group C,the cell survival rate and SOD activity were significantly decreased,MDA content was increased,and the expression of OGG1 mRNA was down-regulated in OGD/R,DEX1,DEX2 and DEX3 groups (P ＜ 0.05).Compared with group OGD/R,the cell survival rate and SOD activity were significantly increased,MDA content was decreased,and the expression of OGG1 mRNA was up-regulated in DEX1,DEX2 and DEX3 groups (P ＜ 0.05).There was no significant difference in the indices mentioned above between DEX1,DEX2 and DEX3 groups (P ＞ 0.05).Conclusion Dexmedetomidine may protect hippocampal neurons against oxidative stress injury by up-regulating the expression of OGG1 mRNA in rat hippocampal neurons subjected to OGD/R.