Effects Of Early Intervention On Functional Outcome And GAP-43 In The Brain Of Rats With Hypoxic-Ischemic Brain Damage

【Objective】 To explore whether early intervention can improve the functional outcome of the rats with hypoxic-ischemic brain damage (HIBD) or not by increasing the levels of growth associated protein –43(GAP-43)in the brain. 【Methods】A rat model with HIBD in uterus was set up by a delayed cesarean section, in which either of the SD pregnant rat's uterine vessels was ligated for 15 min to produce asphyxia. The adjacent horn was not ligated and the fetus in it served as the control. Animals were divided into four groups (the intervention group treated by HIBD, HIBD-IT; the non-intervention group treated by HIBD, HIBD-NIT; the control with intervention group, Control-IT, the control with non-intervention group, Control-NIT)at random and each group included 15 rats for statistics analysis. After 24 h of the operation, the rats of the intervention groups received stimuli of handling , hearing and sight for 14 days, and then they were kept in an enriched environment for 14 days, which were the generally accepted and valid methods of early intervention. The rats of the non-intervention groups were kept in a standard condition without early intervention. The rats' functional outcome was evaluated by the jumping stand test. It was observed the nerve electricity physiology changes in the central nervous system (CNS) by electroencephalogram (EEG).The tapetum histopathology variety was observed in the microscope by the Nissl's staining. GAP-43's levels in the brain were determined by immunohistochemistry method. SPSS11.0 statistical software package proceeds were used for statisitics analysis.【Results】1 The jumping stand test. The frequencies of being shocked by electricity in 5 min among the four groups were different (P<0.05). The frequency of the HIBD-IT rats was found to be significantly shorter when compared with that of the HIBD-NIT rats (P<0.05), Similarly , the frequency of the Control-IT rats was shorter than that of the Control-NIT rats (P<0.05). After 24h, the latency periods before leaving stand firstly among the four groups were different (P<0.05), the time of the HIBD-IT rats was longer than that of the HIBD-NIT rats(P<0.05),and the time of Control-IT rats was longer than that of the Control-NIT rats(P<0.05). The frequencies of doing wrong in 3min among the four groups were different (P<0.05), the frequency of the HIBD-IT rats was shorter than that of the HIBD-NIT rats (P<0.05), the frequency of the Control-IT rats was shorter than that of the Control-NIT rats (P<0.05).2 Electroencephalogram (EEG) . The waves of the Control-NIT rats were mainly α waves ,we may observe βwaves and θ waves sometimes. The background rhythm of Control-IT rats became more regular, the number of α waves became more and the amplitude became higher. In brain waves of HIBD-IT rats ,the amplitude of α waves was lower than that of the Control-NIT rats. In the brain waves of HIBD-NIT rats, we observed not only background rhythm disordered ,but also polymorphic slow waves with high amplitude occurred frequently. Epileptiform waves occurred often. 3 Nissl's staining . Surviving neurons of the four groups were different (P<0.05). Those of Control-IT rats were more than the Control-NIT rats (P<0.05) . Similarly, those of the HIBD-IT rats were more than the HIBD-NIT rats (P<0.05) 4 GAP-43 immunohistochemistry staining. The levels of GAP-43 positive response of the four groups were different (P<0.05). The levels of positive response in the prefrontal cortex and hippocampus of the HIBD-IT rats were higher than that of the HIBD-NIT rats (P<0.05) respectively. Similarly, the levels of positive response of the Control-IT rats were higher than those of the Control-NIT rats (P<0.05) significantly.【Conclusion】 Early intervention through the stimuli of handling ,hearing and sight and enriched environment is one effective way to improve the functional outcome of the HIBD rats. Early intervention can ameliorate the learning and memory ability and relieve the neuron behavior sequela of...