Objective    To study the expression of hypoxia inducible factor-1 alpha (HIF-1α) and HIF-1α mRNA after focal cerebral ischemia reperfusion in rats.     Methods    Adult male SD rats were divided into six groups: sham operation group

5 groups of ischemia/reperfusion (the rats undergoing 2-hour ischemia and then 6-hour

1-day

2-day

3-day and 4-day reperfusion)

with 6 rats in each group. Middle cerebral artery occlusion  (MCAO) was set up in male SD rats according to Longa’ method. The cerebral tissues were analyzed with immunohistochemical methods. The level of HIF-1α protein by immunohistochemical methods and the level of HIF-1α mRNA by in situ hybridization and RT-PCR were detected in the brain tissues.     Results    HIF-1α protein expression started at 6 h after reperfusion

increased remarkably on day 1

reached the peak on day 3

then declined markedly on day 4. HIF-1α mRNA increased at 6 h after reperfusion

peaked on day 3

then declined on day 4. HIF-1α expression was mainly in the periphery of infarcted area at each time point.     Conclusion    High expression of HIF-1α during focal cerebral ischemia/reperfusion in the rat brain tissues

suggests that HIF-1α has neuroprotective effect against cerebral ischemic injury.