Effect Of Recombinant Human Erythropoietin On The Expression Of CNPase And NG2 In The White Matter Of Neonatal Rat Model Of Periventricular Leukomalacia

Objective: To explore the neuroprotective effect of recombinant human erythropoietin(r EPO)on the neonatal rats model of periventricular leukomalacia(PVL)Methods: Postnatal day 3(P3)rats were randomized into three groups: the sham group,the r EPO trail group,and the PVL group.The neonatal rat PVL model was prepared by isolating and ligating the left common carotid artery,and then inhale mixed gas(92%N2+8%O2)for 70 minutes.The r EPO trail group received a single intraperitoneal injection of r EPO(5iu/g-1.d-1)per day for 7day;the PVL group and the sham group received the same volume of saline.At 3th,7th and 14 th day after operation,the pathological changes of brain tissue and myelin sheath were observed by HE staining and luxol fast blue(LFB)staining,and the expression levels of CNPase and NG2 in the white matter around lateral ventricle were detected by immunohistochemistry.Result:1 Postoperative clinical manifestations in the three groups In the early stage of hypoxia,the model rats mainly showed agitation,tachypnea,cyanosis or pallor.With prolonged hypoxia,the neonatal rats of PVL occurred convulsions,hypotonia and lethargy.At the late stage,the neonatal rats with PVL showed growth restriction,the palpebral fissure narrowed,delayed eye opening and thinning hair.However,the r EPO intervention group performed less than the PVL model group.There is no abnormality was found in sham group.2 Pathological changes in the brain tissue of three groups At 3th day after operation,scattered inflammatory cell infiltration,cell edema,neuronal death,and microglia proliferation were seen around the lateral ventricle of the neonatal SD rats in the PVL model group and r EPO trail group.On 7th day after operation,the lateral ventricle of PVL model was significantly dilatate,with multiple liquefaction and sieve softening formation.On 14 th day after operation,the white matter area around the ventricle of the PVL model group showed the formation of cysts,glial scars,brain tissue and corpus callosum atrophy,and the left ventricle was significantly enlarged.At 3th,7th and 14 th day,the pathological changes of r EPO trial group were less than those of PVL model group.No pathological changes were found in the brain tissue of the sham group.3 The myelin luxol fast blue(LFB)staining in three groups At 3th day after operation,the PVL model group and the r EPO trail group showed edema of the myelin sheath,the myelin LFB staining was various degree,and some of the myelin staining were negative.At 7th day after operation,myelin edema become serious and formation of marked vacuoles were seen in the PVL model group and the r EPO trail group.The myelin staining was lighter than at 3th day after surgery.At 14 th day after operation,in the PVL model group,the myelin edema was alleviate,the myelin staining was deepened,and the nerve fibers were disarranged.At 3th,7th and 14 th day after operation,the myelin morphology of the r EPO trail group was similar to that of the PVL model group,but the degree of injury was lighter than that of the PVL model group.At the same time,the sham group had normal nerve fiber structure.4 CNPase and NG2 immunohistochemical staining of three groups4.1 Expression of CNPase in the white matter area around the lateral ventricle CNPase expression was observed in the white matter around the lateral ventricle of neonatal rats with PVL in three groups.At the same time point,the sham operation group,r EPO trail group,and PVL model group were compared(P<0.05).the expression of CNPase of the sham operation group was maximum,followed by the r EPO trail group,and the PVL model group was minimum.There were statistically significant differences at different time points in the same(each)group(P<0.05),the PVL model group and the r EPO trail group had the least expression at 7th day after operation,the most expression at14 th day after operation.4.2 Expression of NG2 in the white matter area around the lateral ventricle NG2 positive expression was observed in the white matter area around the ventricle of the three groups of newborn rats.At the same time point,the r EPO trail group had the highest positive NG2 expression,the PVL model group was moderate,and the sham operation group had the least expression.The difference between two groups was statistically significant(P<0.05).Comparing 3th,7th,and 14 th day after operation in the same group,the NG2 positive expression gradually decreased with time,and the difference was statistically significant(P<0.05).Conclusion:1.r EPO can alleviate the pathological changes of white matter around the lateral ventricle and myelin sheath injury of PVL neonatal rat model,suggesting that r EPO may play an important role in neuroprotection.2.r EPO can promote the expression of CNPase and NG2 in the periventricular white matter of neonatal rat with PVL,it is speculated that exogenous r EPO can mitigate OLs injury caused by ischemia and hypoxia,promote pre-OLs differentiation and myelin repair.