Establishment Of An Animal Model Of White Matter Damage And Research Of The Effect Of Early Treatment

Objective:To establish a 4-day-old SD rat animal model of white matter damage, and observe the changes of pathological morphology and neurobehavioral function of the newborn rats after given early treatment with recombinant human erythropoietin (rHuEPO), monosialotetrahexosylganglioside (GM1), or nerve growth factor (NGF). To discuss the neural protect effects of rHuEPO, GM1 and NGF on newborn rats with ischemia-hypoxia white matter damage, and provide evidence of early treatment on preterm infants.Methods:Totally 290 4-day-old SD rats were randomly divided into 5 groups: sham-operated group, saline (NS) group, EPO group, GM1 group and NGF group. The sham-operated group were only cut open the neck skin and separated the bilateral carotid arteries without occlusion; and the other four groups were subjected to bilateral carotid artery occlusion (BCAO), after that were separately intraperitoneally injected NS 0.01 ml/g, EPO 5 IU/g, GM1 0.02 mg/g, NGF 2 IU/g; GM1 and NGF were repeatedly injected every 24h, totally given 5 doses. The rats were separately killed at 24h, 48h, 72h, 7d and 26d post-operation. After routine H-E dyeing, light microscopy was used to observe brain pathological changes. Immunohistochemistry methods were used to detect the expression of myelin basic protein (MBP),β-amyloid precursor protein (β-APP) and glial fibrillary acidic protein (GFAP) at each observing time-point post-operation. Hanging test, inclined plane test and open field test were performed on the rats 26 days post-operation.Results:1. Weight of four groups of WMD rats were significantly grown slowly. The weight of NS group, EPO group, GM1 group and NGF group were significantly lower than sham-operated group at each observing time-point post-operation (P<0.05). But the weight of EPO group was significantly higher than that of NS group at 7d and 26d post-operation, and the weight of NGF group was significantly higher than that of NS group at 26d post-operation(P<0.05).The weight of GM1 group had no significant difference compared with NS group at each observing time-point post-operation(P>0.05).2. After ischemia-hypoxia, light microscopy showed periventricular white matter damage, included cell swollen, necrosis and apoptosis, tissue loose and lateral ventricle enlarging. Under light microscopy, the pathological changes of EPO group, GM1 group and NGF group had no obvious differences between them; but when compared with NS group, the range of necrosis was smaller at 72h post-operation, and the extent of lateral ventricle enlarging was smaller at 7d and 26d post-operation.3. After ischemia-hypoxia, the immunohistochemistry dyeing showed that the percentage of MBP positive cells was decreased, andβ- APP, GFAP positive cells percentages were increased. After treated with rHuEPO, GM1, NGF, the percentage of MBP positive cells increased significantly than that of NS group at 72h or 7d post-operation; APP positive cells percentage decreased significantly than that of NS group at 72h, 7d or 26d post-operation; GFAP positive cells percentage decreased significantly than that of NS group at 48h, 72h, 7d or 26d post-operation(P<0.05).4. When 30-day-old, the NS group, EPO group, GM1 group and NGF group rats responsed stolidly, their autonomic acivities reduced, flexibility and stability decreased. The results of hanging test, inclined plane test and open field test of NS group were significantly worse than those of sham-operated group(P<0.05). The results of hanging test, inclined plane test and open field test of EPO group, GM1 group and NGF group were significantly better than those of NS group. (P<0.05)Conclusion:Using 4-day-old SD rat with BCAO, an animal model of white matter damage can be successfully set up. Early treatment with rHuEPO, GM1 or NGF can improve the rat's growth and repair of WMD, and ameliorate the rat's neurobehavioral function.