RESUMO
<p><b>OBJECTIVE</b>To study the neuroprotective effect of hypoxic preconditioning on reperfusion injury following ischemia and its molecular mechanism.</p><p><b>METHODS</b>Forty-eight rats were randomized into 3 groups, namely the sham operated group, ischemia/reperfusion (I/R) group, and I/R following hypoxic preconditioning group (HP+I/R). In the latter two groups, the rats were subjected to middle cerebral artery occlusion (MACO) for 3 h followed by reperfusion for 24 h to induce cerebral I/R injury. The learning and memory ability of the rats 24 h after reperfusion was assessed using Y-maze test. Immunohistochemistry was performed to quantify the expressions of survivin and HSP-70 proteins in the rat brain tissues.</p><p><b>RESULTS</b>The number of survivin- and HSP-70-positive cells in the brain tissues was significantly different between HP+I/R group and IR and the sham operated groups (P<0.05), and following I/R injury, the rats in HP+I/R group showed much better performance in the Y-maze test than those in I/R group.</p><p><b>CONCLUSION</b>Hypoxic preconditioning can protect the ischemic brain against reperfusion injury, promote recovery of the learning and memory ability and neurological functions following the injury. Up-regulation of the expressions of survivin and HSP-70 proteins might be one of the molecular mechanisms for this neuroprotective effect.</p>