| [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 endogenetic nerve growth factor (NGF) in the brain.[Methods]A rat model with HIBD in uterus was set up by a delayed cesarean section, which either of the SD pregnant rats' uterine vessels was ligated for 15 min to produce asphyxia. The adjacent horn was not ligated and the fetuses in it served as the controls. Animals were divided into four groups at random and each one was 20. Because of the accidental death in the course of the experiment, the intervention group treated by HIBD was 18, the non-intervention group treated by HIBD was 17, the control with intervention group was 18, and the control with non-intervention group was 19 at last. All the rats were kept under a regular day and night (lights on and off at 12 h) with free access to food pellets and water. After 24 h of the operation, the intervention groups received the neonatal handling and were kept in an enriched environment, which are the generally accepted and valid methods of early intervention, for 28 days. The non-intervention groups were kept in a standard condition without the neonatal handling and enriched environment. The rats' functional outcome was evaluated by suspension test, beam-walking test, and one trial passive avoidance response test. It was observed the nerve electricity physiology changes in the central nervous system (CNS) by brainstem auditory evoked potential (BAEP). The tapetum histopathology variety was observed in the microscope after the HE staining. NGF levels in the brain were determined by an enzyme-linked immunosorbent assay (ELISA) method. It was examined the results by SPSS11.0 statistical software package proceeds.[ Results ](1) In the behavior test, the results of the suspension test were not different (P>0.05), the ones of the beam-walking test and one trial passive avoidance response test were much different (F =7.31, x2=20.86, P<0.05) in all the rats. The time crossed the beam for the intervention group treated by HIBD (8.11 ±2.89)s was much shorter than that for the non-intervention group treated by HIBD (10.47±3.46)s (P<0.05) and the same as compared with that for the controls (6.06± 1.89)s, (8.05 ± 2.46)s (P>0.05). The time crossed the beam for the control with intervention group was much shorter than that for the control with non-intervention group (P<0.05). The medial step-through latency (STL) of the intervention group treated by HIBD (177.5s) was much longer than that of the non-intervention group treated by HIBD (98.00s) (P<0.05) and was the same as compared with that of the control with non-intervention group (180.00s) (P>0.05), but was much shorter than that of the control with intervention group (281.50s) (P<0.01). The STL of the control with intervention group was much longer than that of the control with non-intervention group (P<0.05).(2) In the results of BAEP, the peak latency (PL) of waves I, II, IV and the interpeak latency (IPL) of wave II- IV, I~IV were much different (FI=2.59, FII=3.62, FIV=14.92,FII-IV= 8.85,FI-IV=11.46,P<0.05) in all the rats. In the intervention group treated by HIBD, the PL of waves II, IV (2.21 ±0.11)ms, (4.13±0.15)ms and the IPL of wave I ~ IV (2.74±0.10)ms were much shorter than those of the non-intervention group treated by HIBD (2.30±0.09)ms, (4.25±0.16)ms, (2.80±0.17)ms (P<0.05) and all the waves were the same as compared with those of the control with non-intervention group (P>0.05), but the PL of wave IV and the IPL of waves II-IV (1.91 ±0.09)ms, I-IV were much longer than those of the control with intervention group (3.93±0.17)ms, (1.74 ±0.15)ms, (2.58±0.14)ms (P<0.05). At the same time, the PL of wave IV and the IPL of waves II~IV, I~IV in the control with intervention group were much shorted as compared with those in the control with non-intervention gro... |
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