Genistein postconditioning protects neurons against ischemic injury through eNOS activation in hippocampal CA1 region

Objective To investigate the neuroprotective role of Genistein postconditioning(GPC) against cerebral ischemic injury and its effects on the level of eNOS phosphorylation in hippocampal CA1 region of rats.Methods The rats were subjected to global cerebral ischemia by four-vessel occlusion and randomly divided into five groups,sham,ischemia/reperfusion(I/R),GPC(intravenously through the tail vein),L-NAME(an inhibitor of NOS,icv.) and vehicle(I/R+DMSO,I/R+Genistein+NaCl) groups.The protein level of p-eNOS and eNOS was detected by Western blotting.Additionally,NeuN staining and TUNEL analysis was used to detect the survival neurons and apoptotic neurons of hippocampal CA1 region,respectively by Laser Scanning Confocal Microscope.Results Compared with I/R groups,in GPC groups p-eNOS levels at 30 min or 3 d of reperfusion significantly in-creased(P0.001),while eNOS protein expression in all time points had no obviously change.GPC groups compared with I/R groups,the number of surviving neurons of hippocampal CA1 region significantly increased(213.0±21.0 vs 45.0±15.0,P 0.05) and apoptotic neurons markedly reduced(29.0±6.0 vs 192.0±31.0,P0.05).Furthermore,L-NAME can not only significantly abate neuroprotection induced by genistein postconditioning(P0.05),but also effectively reduce the level of p-eNOS(1.149±0.218 vs 1.583±0.155,P0.001).Conclusions GPC significantly prevents neuronal injury from global cerebral ischemia in the hippocampal CA1 region of rats.The mechanism might be explained by the increase of p-eNOS level.