| 0bjective:To explore the neuro-protection and neuro-protective mechanism of erythropoietin(EPO) by studying its effect on Neuroglobin ( NGB ) and monocyte chemoattractant protein-1 (MCP-1) expression following focal cerebral ischemia-reperfusion in rats.Methods:ninety-six healthy male Spragne-Dawley rats were randomly divided into 4 groups: normal control group(normal group).sham operation group.model control group(model group)and EPO preconditioning group (EPOgroup).Each group had Twenty-four rats, which were randomly divided into 3 subgroups by three time spots,At 2hours before and 6hours or 24 hours after cerebral ischemia . Each subgroup had eight rats. The model of middle cerebral artery occlusion (MCAO)by suture embolus was establushed according to Longa's report.EPO group received an intraperitoneal injection of EPO 3000u/kg body weight at very onset of ischemia,while model group and sham operation group received same doses of saline.The model group and EPO group were made by occluding middle cerebral artery 2 hours ,sham operation group was pluged in by thread 2 hours ,then reperfusion 72 hours. The scores of behavior obstacle in rats were rated by Longa's report at different time after reperfusion,and then executed them to obtain the brains.Normal group were executed and obtained brains. All the brains were formed by paraffin section.HE staining, Nissl staining and immunohistochemistry staining were used to observe pathological changes and the expression of NGB and MCP-1 in cerebral cortex of ischemic side. All the datas were proceessed through two-way ANOVA analysis of SPSS13.0 for windows.The significant testing standard was P<0.05 or P<0.01. ResultsThe scores of neurologic impairmentAfter 72h ischemia-reperfusion ,EPO group subgroups neurological deficit score was significantly lower than the model group the appropriate subgroup. Corresponding subgroups of each group were significantly different (P <0.01), the normal group and sham group in each sub-group score was 0 points.2 HE stainingIn normal group and sham operation group, nerve cell degenerationand necrosis was rarely.In model group,we found that neuron was raref-action , cell spaces was accreted and there existed a lot of degeneratedand necrotic neurons,it mainly displayed cell body. shrinkage, karyopycnosis and chromatospherite vanished.But EPO group had more survival nervecells and the degree of injury was obviously lessen.3 Nissl's stainingIn normal control group and sham operation group,normal cell cellenvelope was amethyst,nucelus was light blue color, cells lined up in order,there were many mauve Nissl's bodies in nerve cell.In model group ,Nissl's bodies were very seldom or dissolved and vanished. EPO group compared with model group , Nissl's bodies increase.4 Expression of NGB in brain tissueEach group's positive cells of NGB compared: it had no sta-tistical significance between normal group and sham operation group(P>0.05). Normal group compared with model group and EPO group , sham operation group compared with model group and EPO group , model group compared with EPO group, all had statistical significant difference(P<0.01). Model group was higher than any other groups,and EPO group descend, there was only a few masculine cell expression in normal group and sham operation group.It had statistical significance among different time spot(P<0.01),-2 hours compared with+6 hours ,-2hours compared with +24 hours had significant difference (P<0.01),but +6hours compared with +24 hours had no significant difference (P>0.05).5 Expression of MCP-1 in brain tissueIn each group could be seen the expression of MCP-1 positive cells, in which the normal group and sham-operated group shows a small amount of brown-yellow granules scattered in the cortex and hippocampus, the difference was no significant (P> 0. 05); ischemia reperfusion group, MCP-1 expression at different time points, EPOgroup-2h group was significantly higher than the normal group and sham operation group (P < 0.01); with ischemia-reperfusion group, the intervention group significantly reduced brown-yellow granules (P <0. 01))Conclusions:1 In cerebral ischemia reperfusion injury in rats EPO preconditioning group can inhibit nerve cell degeneration, necrosis and diminish be havioral disturbance caused by ischemic reperfusion injury.2 The mechanism of neuroprotective effect of EPO possibly maybe concerned with reducing the expression of MCP-1 and increasing the expression of NGB . it showed that EPO participant in antiinflammatory and anti-apoptosis. And the experiment suggested the role of cerebral protection and intervention time-related, intervention sooner, the protective effect of markedly effective.
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