Abstract: Objective To investigate the neuroprotective role of genistein postconditioning (GPC) against cerebral ischemic injury and its effects on phosphorylation (activation) and protein expression of eNOS in hippocampal CA1 region of rats. Methods Cerebral ischemia was induced by four-vessel occlusion in rats and protein level of p-eNOS and eNOS were detected by Western Blotting. Additionally, NeuN staining was used to detect the survival neurons and apoptotic neurons of hippocampal CA1 region was observed using TUNEL analysis by Laser Scanning Confocal Microscope. Results In I/R groups, the number of NeuN-positive cell in hippocampal CA1 region was significant reduce accompanied with the increase of apoptotic neurons compared with sham groups. By contrast, treatment with Genistein after ischemia markedly protected the pyramidal neurons, as evidenced by the increase of NeuN-positive cell and the decrease of apoptotic neurons. Furthermore, L-NAME, an inhibitor of NOS abolished the neuroprotective role induced by genistein postconditioning. Additionally, immunoblot analysis showed that eNOS protein expression had no significant change in different times, while the level of p-eNOS significantly increased with two peaks occurring at 30min and 3d of reperfusion compared with I/R groups. L-NAME significantly suppressed enhance of p-eNOS induced by GPC at 3d of reperfusion. Conclusions GPC significantly prevents neuronal injury from global cerebral ischemia in the hippocampal CA1 region of rats. The possible mechanism is involved in the increase of p-eNOS expression.

Key words: Genistein Postconditioning, Cerebral ischemia/reperfusion, p-eNOS, Hippocampus CA1 region