Effects Of Erythropoietin On Myelin Basic Protein、CD68and Neurological Behavior In Neonatal Rats With White Brain Damage After Intrauterine Infection

Objective:To explore the neuroprotective effect of recombinant human erythropoietin (rhEPO) on neonatal rats with white matter damage (WMD) after intrauterine infection.Methods:25wistar rats at15days of gestation were randomly divided into two groups:infection group (n=20) and non-infection group (n=5). The infection group was established animal model of intrauterine infection by intraperitoneal injection of lipopolysaccharide (LPS) while the non-infection group received the same volume of saline injection instead. Then, we observed the rate of premature delivery、the average number of live neonatal rats of every delivery and the birth weight of the two groups. The pathological examination of placental tissues was given after the two groups of pregnant rats delivery. The preterm and full term neonatal rats from infection group were randomly selected6after brith immediately to be decapitated after perfusion with formaldehyde and stained with HE to observe the pathological changes of the brain tissues. And other neonatal rats in the infection group were randomly divided into EPO group (n=49, which were given rhEPO (5000IU/kg) through intraperitoneal injection immediately after delivery) and infected control group(n=49, which were injected the same volume of normal saline injection).49neonatal rats which were randomly selected from the non-infection group were regarded as the normal control group.10rats which were randomly selected in each group were decapitated after perfusion with formaldehyde at1、3、7days of age. Then the rat brains which were cut into slices after paraffin embedding were HE stained to detect brain tissue changes; Myelin Basic Protein (MBP) and CD68expression were detected by immumofluorescence method. Neurobehavioral tests were performed at30days of age.Results:1. The general situation:There were3pregnant rats early delivery which were excluded in the infection group and the rate of premature delivery was15%; there were total of114full-term neonatal rats in this group, while10of them died so the survival rate was91.22%. The average number of live neonatal rats of every delivery and the birth weight of the two groups were all significantly decreased(P<0.05)2. Pathological examination of placental tissues:the placenta of rats in infection group showed vascular engorgement、dropsy and neutrophilic granulocyte soak.3. HE staining of brains:Loose structure of the white matter of premature rats was obvious and the neurons were lack of differentiation with small cell volume、 small nucleus and little neuronal process. Weaking staining and focal rarefaction of the periventricular white matter of the infection group were observed. Clear staining and normal structure of periventricular white matter were show in non-infection group.4. MBP immunofluorescence staining:Each group had no positive staining of MBP at1and3days of age, while we observed the situation that demyelination at7days of age in the infected control group and the MBP was much lower in the infected control group than the normal control group significantly (P<0.05). Moreover, the level of MBP in the EPO group was higher than that of the infected control group. And there was significant difference among these groups (P<0.05).5. CD68immunofluorescence staining:Each group had no positive staining of CD68at1days of age, while the level of the expression of CD68at3and7days of age rats in the infected group was higher than normal group significantly (P<0.05). Moreover, the level of the expression of CD68in the EPO group was much lower than in the infected control group. And there were significant difference among these groups (P<0.05).6. Neurobehavioral tests:The infected control group had lower score than normal control group in Neurobehavioral tests and the EPO group had higher score than the infected group, and there were significant differences(P<0.05) between two groups.Conclusions:1. Intraperitoneal injection of LPS can lead to intrauterine infection and the model of intrauterine infection in rats were established successfully.2. Intrauterine infection can lead to premature delivery, low birth weight and low survival rate.3. Intrauterine infection can lead to white matter brain damage in the neonatal rat.4. Oligodendrocyte injury, myelination disorder and microglia excessive activation are the mainly pathogenic manifestations of the white matter damage of neonatal rats.5. EPO treatment can reduce the white matter damage by reducing the injury of oligodendrocyte and myelination obstacles, and restraining the activation of microglia, as well as can improve neuro-behavior performance.