| Objective:Hypoxic-ischemic brain damage(HIBD) is an important complicating disease of suffocation in the human perinatal period.It not only severely impairs neonates' lives and healthes but also often results in eternal dysfunctions.And there are scarcely ideal and effective means of prevention and therapy now.The studies to numerous animals indicated that environment stimulus and voluntary exercises could promote the changes of structure and function in brain.This research was aim to study the expression of N-methyl-D-aspartate(NMDA) receptor NR1 subunit protein and morphorlogical changes in hippocampus,also test spatial memory abilities of neonatal rats with HIBD and observe their changes after interventions with enriched environment and hydrotherapy,investigate the intervention effects and explore the possible mechanisms on neonatal rat models with HIBD,provide theoretical basis to taking enriched environment and hydrotherapy as a clinical therapy hypoxic-ischemic encephalopathy(HIE) as well.Methods:The established HIBD rats were randomly divided into intervention group and non-intervention group.The intervention group included three groups:enriched environment group,hydrotherapy group and enriched environment+hydrotherapy group. The sham-operation rats were served as normal control group.The intervention group were treated by different method respectively for 28 days since the 2nd day after HIBD.In rats 15d,22d,29d and 36d after birth,the weighe were measured.Immunohistochemistry method was used to detect the expression of NMDA receptor NR1 subunit in hippocampal CA1 region at different time-points.And HE stain was employed to observe the morphorlogical changes in hippocampus of rats 36d after birth.In rats 37 day after birth, Morris water maze was used to evaluate the learning and memory abilities after intervention.Then the electron microscope was used to observe the ultrastructure changes in hippocampus of rats.Results: 1.In neonatal rats 8 day after hypoxia-ischemia(HI),the weight of sham group was much higher than that of intervention group and non-intervention group(p＜0.01),there was no significant difference compared intervention group with non-intervention group(p＞0.05).In rats 15d,22d,29d after HI,the weights of intervention group and sham group were much higher than that of non-intervention group(p＜0.01),there was no marked difference between intervention group and sham group(p＞0.05).2.Since neonatal rats 8 day after HI,histopathologic examination of the ligated side of brains showed atrophy,regional infarcttion of cortex and striatum.And non-intervention was obviously anmomal.The result of HE stain showed the morphology in the tow-sided hippocampus of sham group was nomal,and that in the left-sided hippocampus of intervention group was minimal abnormal,the neurons almost arranged orderly,some neurons lost.While the moophorligy of non-intervention group was obviously abnormal, the neurons arranged disorderly,many neurons lost and the nuclenses were not clear.3.The result of examination with transmission electron microscopy were as follows:In neonatal rats 40 day after birth,normal neuron morphology,moderate stainable feature, chromosome density,abundant synapfic vesicles and postsynaptic density(PSD) were observed in sham group.In intervention group,no apparent pathologic changes were found in neuron of left-sided hippocampus at same time-point.However,synaptic vesicles and PSD decreased slightly.Those of enriched environment group and enriched environment+hydrotherapy group were more than those of hydrotherapy group as well.In non-intervention group,neuronal shrinkage,nuclear membrane di-nucleolus,chromosome denseness,synapfic vesicles and PSD apparent decrease in left-sided hippocampus were found.4.The water maze scores of intervention group and sham group in place navigation test and spatial probe test were much higher than that of non-intervention group(p＜0.01). There was no marked difference between the enriched environment group,enriched environment+hydrotherapy group and sham group(p＞0.05).However,the scores were reduced notably in non-intervention group compared with sham group(p＜0.01).5.In neonatal rats 29 day after HI,The expression of NR1 in hippocampal CA1 region was increased obviously in intervention group compared with non-intervention group. There was no significant difference between the enriched environment group,enriched environment+hydrotherapy group and sham group(p＞0.05).However,it was decreased obviously in hydrotherapy group compared with sham group(p＜0.05).Conclusion:Compared to rats with HIBD of non-intervention group,the weight of rats with HIBD of intervention group increased obviously,the damage in pathology of hippocampus decreased,the expression of NMDA receptor protein increased,and the abilities of learning and memory improved,which indicated that enriched environment stimulus and hydrotherapy can promote the recovery from HIBD.In addition,there were no significant differences in the expression of NMDA receptor protein and the abilities of learning and memory compared enriched environment group and enriched environment+ hydrotherapy group with sham group.However,those significantly decreased in hydrotherapy group compared with sham group.It indicated that the intervention effects of enriched environment and combined application of enriched environment stimulus and hydrotherapy is better than hydrotherapy.The change of NMDA receptor NR1 subunit in hippocampus might be one of the mechanism. |
PDF Full Text Request