| 0bjective:To investigate the effect of erythropoietin on cerebral interleukin-1βand intercellular adhesion molecule-1 expression in MCAO followed reperfusion in rats,and to explore the protective mechanism of erythropoietin on inflammatory injury.Methods:Seventy-two 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 eighteen, which were randomly divided into 3 subgroups by three time spots . Each subgroup had six. The model of middle cerebral artery occlusion (MCAO)by suture embolus was established 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 6 hours,24 hours,48 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 IL-1βand ICAM-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. Results:1. The scores of neurologic impairment In normal group and sham operation group were 0 at 6 hours,24 hours,48 hours , while EPO group were 1.67±0.52,1.83±0.41,1.67±0.52,model group were 2.17±0.75,2.50±0.55,2.67±0.52. The scores of EPO group were lessen than model group ,it had significant difference between them(P<0.001). But there were no significant difference at different time(P>0.05).2.HE staining In normal group and sham operation group, nerve cell degeneration and necrosis was rarely.In model group,we found that neuron was rarefaction , cell spaces was accreted and there existed a lot of degenerated and necrotic neurons,it mainly displayed cell body shrinkage,karyopycnosis and chromatospherite vanished.But EPO group had more survival nerve cells and the degree of injury was obviously lessen.3.Nissl's staining In normal control group and sham operation group,normal cell cell envelope 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 IL-1βin brain tissue Each group's positive cells of IL-1βcompared: it had no statistical 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<0.001). 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<0.001), 24 hours compared with 6 hours , 48 hours compared with 24 hours had significant difference (P<0.001),but 48 hours compared with 6 hours had no significant difference (P>0.05).Expression of masculine cells population of model group and EPO group increased at 6 hours, achieved peak at 24 hours,then decreased at 48 hours. 5.Expression of ICAM-1 in brain tissue Each group's positive cells of ICAM-1 compared: it had no statistical 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<0.001). 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<0.001), 6 hours compared with 24 hours, 24 hours compared with 48 hours had significant difference (P<0.001),but 6 hours compared with 48 hours had no significant difference (P>0.05).Expression of masculine cells population of model group and EPO group increased at 6 hours, achieved peak at 24 hours,then decreased at 48 hours.6 Correlative analysis between IL-1βand ICAM-1 Through correlative analysis,there is clear positive correlation between them in model group(r=0.936,P<0.001),also it has clear positive correlation in EPO group(r=0.945,P<0.001).Conclusions1 In cerebral ischemia reperfusion injury in rats EPO preconditioning group could inhibit nerve cell degeneration,necrosis and diminish behavioral disturbance caused by ischemic reperfusion injury.2 EPO could inhibit the expression of IL-1βand ICAM-1 in brains of cerebral ischemia reperfusion injury in rats,it showed that EPO participant inflammatory response;.3 The mechanism of neuroprotective effect of EPO possibly maybe concerned with reducing the expression of IL-1βand ICAM-1 .
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