Effect Of Recombinant Human Erythropoietin On The Expression Of O4 And O1 In The White Matter Of Neonatal Rat Model Of Periventricular Leukomalacia

Objective:Establish an animal model of periventricular white matter（PVL）in neonatal SD rats,recombinant human erythropoietin（rhEPO）was given by intraperitoneal injection in rhEPO intervention group.To explore the neuroprotective effect of rhEPO on animal model of PVL.Methods:Postnatal day 3 SD rats were selected（48 rats）,and their left common carotid artery was ligated.Then 92%N₂+8%O₂gas was inhaled for 1 hour to made PVL animal model.They were randomly divided into the rhEPO intervention groups（24 rats）and the PVL model group（24rats）.Another 24 rats were prepared by isolating and ligating the left common carotid artery as the sham operation group.The rhEPO intervention group received a single intraperitoneal injection of rhEPO（5 IU/g.d）per day for 7day,the PVL model group and the sham operation group were given an equal volume of normal saline.The brain tissues of 8 rats in each group were randomly gained at 3th,7th and 14th day after operation.The pathological changes of brain tissue and myelin sheath were observed by HE staining and Luxol fast blue（LFB）staining.The expression levels of Oligodendrocyte marker O4 and O1 in the white matter around lateral ventricle were detected by immunohistochemistry.Results:1 Pathological change of brain tissuesIn the sham operation group,cells in the white matter around lateral ventricle were arranged neatly,had clear outlines and complete structures at all the time after operation.And the bilateral lateral ventricles were symmetrical.At 3th day after operation,neuronal edema,loose arrangement and disorder,inflammatory cell infiltration and more microglia were seen around the lateral ventricle of the SD rats in the PVL model group.At 7th day after operation,nerve cell edema,necrosis and tissue loosening were seen.The liquefaction necrosis,ethmoid necrosis and cyst formation were seen too,and the left lateral ventricle was slightly enlarged.At 14th day after operation,glial scars were seen in the white matter area and the left lateral ventricle was significantly enlarged.At 3th,7th and 14th days after operation,the damage degree of pathological changes in the rhEPO intervention group was mild compared with the PVL model group.2 Myelin sheath LFB stainingAt 3th day after operation,the PVL model group showed the edema of myelin sheath.The myelin sheath arranged sparsely and the myelin LFB staining was various degree.At7th day after operation,myelin sheath was sparse and lighter than before.The myelin edema became severely and a large number of vacuoles were formed.At 14th day after operation,myelin edema in the PVL model group was relieved compared to before,and the nerve fibers were disarranged stripey and reticulated.The rhEPO intervention group had improved in myelin sheath sparseness.At 7th and 14th days after operation,compared with the PVL model group,the myelin edema and rupture were alleviated in rhEPO intervention group.The sham operation group has clear myelin structure,uniform thickness and regular nerve fibers at 3th,7th and 14th days after operation.3 Immunohistochemical staining3.1 O4 expression in the white matter around lateral ventricleAt the same time point,the expression of O4 in the sham operation group was the most,the rhEPO intervention group second,and the PVL model group least.The difference was statistically significant（P<0.05）.In comparison of different time points in the same group,the expression of O4 showed a downward trend with the increase of days.The difference was statistically significant（P<0.05）.3.2 O1 expression in the white matter around lateral ventricleAt the same time point,the expression of O1 in the sham operation group was the most,the rhEPO intervention group second,and the PVL model group least.The difference was statistically significant（P<0.05）.In comparison of different time points in the same group,the expression of O1 showed a downward trend with the increase of days.The difference was statistically significant（P<0.05）.Conclusion:1.rhEPO can mitigate the pathological changes and myelin damage in the white matter around lateral ventricle of the PVL rats,suggesting that rhEPO may play role in the neuroprotective effect.2.rhEPO can promote the expression of O4 and O1 in the white matter around lateral ventricle of the PVL rats,suggesting that rhEPO can relieve the damage of oligodendrocyte and promote the pre-myelinating oligodendrocyte differentiation and myelin repairment.