The kinetic changes in the expression of neuroglobin(NGB)in mouse hippocampus after transient forebrain ischemia-reperfusion at different time points were investigated and the significance of these changes was discussed.The C57BL/6 mice model of ischemia-reperfusion was established by transient occlusion double side carotid artery under micromanipulation.RT-PCR was used to detect the dynamic changes in NGB mRNA expression(transcription level)and Western blotting was used to detect the dynamic changes in NGB protein expression(translation level).The results demonstrated that,compared with sham-operated control group(100±0.00),the expression of NGB mRNA increased initially at 6 h after reperfusion(132.59±28.26,P <0.05),reached a peak at 24 h(157.36±13.85,P<0.001),degraded since 48 h(146.55±23.17,P<0.01)and the expression of NGB mRNA dramatically dropped down nearly to normal level at 72 h(118.42±34.23,P>0.05)after reperfusion.A similar tendency was found in the expression of NGB protein compared with sham-operated control group(100±0.00).The NGB protein increased little at 6 h after reperfusion(111.46±23.54,P>0.05),reached a peak at 24 h(141.25±32.12,P<0.01)and degraded since 48 h(138.02±19.68,P<0.05).The expression of NGB protein dramatically dropped down to nearly normal level at 72 h(119.29±35.18,P>0.05)after reperfusion.The results indicate that the increased expression of NGB mRNA and protein at different phase point after reperfusion might be an irritable protective effects against ischemia-reperfusion brain damage,but the duration of its expression is short(within 48 h).