The Changes of Long-term Behavior and Brain Morphology after Systematic Hypoxia Exposure in Neonatal Rats

［Abstract］Objective To investigate the change of long-term behavior， brain morphology and myelin basic protein （MBP） expression after systematic hypoxia exposure in P0d neonatal rats. Methods P0d neonatal SD rats were randomly and equally divided into control group（NG group）and systematic hypoxia group（Hy group）. Hy group rats were exposed to 5%O2 for 3.5h. Behavior tests were applied at P29d and P30d. 1.5T MRI scanning of brain was used to detect morphology change in P60d rats after hypoxia. The changes in ultrastructure of hippocampal CA1 and corpus callosum（CC）after hypoxia were further confirmed by transmission electron microscopy（TEM）. Immunoblotting assays were performed to identify the dynamic changes of MBP. Results（1）The scores in refused captured test，open field test，slope experiments and the suspension test decreased（P < 0.05）. The success rates of Y arm maze test decreased and days up to standard significantly prolonged （P < 0.001）. （2）Abnormal signal in hippocampus and lateral ventricle， thinner corpus callosum were observed by 1.5T MRI scanning after hypoxia 2 months. （3）Electron microscope results revealed loosen structure and neuropil edema appeared in periventricular white matter. （4）The expression of MBP in the periventricular regions of NG group was detected by immunoblotting assay at the early development stages. Systemic hypoxia exposure to neonatal rats could decrease MBP expression after hypoxia 3 days but increase expression after hypoxia 4 hours（P < 0.05）. Conclusion An obviously morphology injury which distinct located in periventricular white matter（PWM）and the abnormal of the long-term behavior can be confirmed after systematic hypoxia exposure in neonatal rats.