Abstract:
Objective：To investigate the effect of early hyperbaric oxygen(HBO) in protecting brain nerves of neonatal rats with hypoxic ischemic brain damage(HIBD).
Methods：A total of 120 7-day old neonatal Wistar rats were randomly divided into sham operation group(control group), hypoxic ischemic brain injury group(group HIBD) and hyperbaric oxygen group(HBO group), with 40 rats in each group. The HBO group was randomly divided into early hyperbaric oxygen subgroups(EHBO subgroup) and late hyperbaric oxygen subgroups(LHBO subgroup),with 20 rats in each group. After establishing the HIBD model for all rats(control group with sham operation),hyperbaric oxygen treatment was performed in EHBO subgroup after 1 h, and in LHBO subgroup after 48 h(2 ATA, every 90 minutes, 24 hours once, continuous treatment of 7 day).After treatment, the rats in subgroups were killed, and the same number of rats in the control group and HIBD group were also killed. Hippocampus Nestin in the nerve of rat was determined using immunohistochemical method, and learning and memory function in rats were tested using the Morris water maze test.
 Results：In the control group Nestin positive cell detection rate was (10.26±1.37)/HP, in EHBO subgroup it was (15.82±2.19)/HP, LHBO subgroup (32.64±4.83)/HP, HIBD group (36.18±4.02)/HP. The detection rate of Nestin positive cells in the HBO group, and HIBD group was significantly higher than that of the control group(P<0.05), and in the LHBO subgroup it was significantly higher compared with that of the EHBO subgroups(P<0.05), while the LHBO subgroup and HIBD group had no significant difference(P>0.05); the four groups had significant differences in average EL (F=24.18, P<0.05);the rats in control group，EHBO and LHBO group had significant difference in the search time and search distance(F=21.05, P<0.05), but there was no significant difference between LHBO and HIBD groups and among the groups in search time(P>0.05).
 Conclusion：Early BHO has protective effect on brain injury;Nestin protein may be involved in the repair of brain nerves;early HBO can improve the future learning and memory function which is impaired by HIBD.

Key words: hypoxic ischemic brain damage, hyperbaric oxygen, Cranial nerve, Wistar rat, animal,experiment