Effects Of Early Interventions On Brain Functional Outcome And Neuron Apoptosis Of Rats With Hypoxic-ischemic Brain Damage

[Objective]To explore the effects of early interventions on functional outcomes and neuron apoptosis in the brain of neonatal rats with HIBD.[Methods]A fetal rat model of HIBD was set up by ligating unilateral uterine horn vessel of pregnant SD rat for 15 minutes , and then the affected fetuses (total 30) were divided into two groups: the intervention group with HIBD (15) and the non-intervention group with HIBD(15) . The fetuses in the contralateral horn whose uterine horn vessel was not ligated served as controls (total 30) were divided into two groups: the normal group (15) and the normal intervention group(15). Two intervention groups were kept in an enriched environment for 28 days, the others were kept in a standard condition without early interventions. Early interventions included the stimuli of neonatal handling, hearing, sight and enriched environmental stimulate, which were generally accepted as the valid methods of early intervention. The brain functional outcomes of rats were evaluated by water-maze test and short-latency samatosensory evoked potentials (SLSEP). Terminal dexoxy nucleotidyl tranferase mediated d-UTP-biotin nick end labeling (Tunel) and electron microscopy were used to detect neuron apoptosis in forehead cortex and hippocampus CA1 region of rats. It was examined the results by SPSS 11.0 ststistical software package proceeds.[Results]1 The score of water maze test was better in the normal intervention group (6.53 1.89times) than in other groups, P<0.05. There was no difference between the intervention group with HIBD (8.47 1.92times) and the normal group (8.53 1.24times), P>0.05. Compare to the intervention group with HIBD, the non-intervention group with HIBD got the worse score of water maze test (10.97 1.92times) , P<0.05.2. The non- intervention group with HIBD had significantly prolonged PL (17.76 1.75 ms) of Nl wave and IPL of wave P1-N1 (7.07 1.60ms)(P<0.05). There was no difference between the intervention group with HIBD (16.51 1.96ms; 5.86 1.41ms) and the normal group (16.17 1.73ms; 5.49 0.99ms)(P>0.05). Compare to the normal group, the normal intervention group (14.58 1.19ms; 4.53?.93ms) largely shortened the PL of Nl wave and IPL of wave P1-N1 (P<0.05) .There was no difference about the PL of PI wave of four groups (P>0.05) .3.The median of apoptosis positive neurons in forehead cortex and hippocampus CA1 section of rats in non-intervention group with HIBD were 8.00 and 9.00 cells/mm2 respectively, that were significantly higher than those of intervention group with HIBD 5.00 and 6.00 cells/mm2, P<0.05. Apoptosis neurons in the normal group were 2.00 and 4.00 cells/mm2 were much more than the normal intervention group 0.00 and 2.00 cells/mm2, P<0.05. The difference of apoptosis neurons was also significant between the normal group and the intervention group with HIBD, P<0.01.4 Electron microscopy: Typical apoptotic neuron could be seen in the hippocampal CA1 region.5 There were correlations between the results of water maze and the sum of apoptosis neurons in the forehead cortex, SLSEP and apoptosis neurons in the forehead cortex, water maze and SLSEP.[Conclusion]Early intervention is one of the effective ways in improving the functional outcomes with the hypoxic-ischemic brain damage rats, through a possible mechanism to decrease the ratio of neuronal apoptosis in forehead cortex and hippocampus CA1 section.