The effects of hyperbaric oxygen in reducing brain damage from hypoxic ischemia in neonatal rats / 中华物理医学与康复杂志

ABSTRACT

Objective To investigate the protective effects of hyperbaric oxygen(HBO)against brain dam- age from hypoxic ischemia(HIBD)in neonatal rats.Methods One hundred and seventeen 7-day-old Sprague- Dawley rats were randomly divided into 4 groupsa control group(n=32),a hypoxic ischemia brain damage group (HIBD group,n=30),a hyperbaric air group(HBA group,n=27),and a hyperbaric oxygen group(HBO group, n=28).The HIBD model was established by permanent occlusion of the left common carotid artery followed by expo- sure to a mixture of 8% oxygen/92% nitrogen for 2 h(at 37℃).HBO therapy was administered to the HBO group after the hypoxia exposure once a day for 7 d,as was HBA therapy to the HBA group.Apoptotic cells in the cortex and hippocampus(A_(CH)cells)were measured using TUNEL at 9 d after birth,and the ratios of left and right cerebral hemisphere weight(R_(L/R))and rate of weight gain(GRW)were recorded 14 d after birth.A radial arm maze acquisi- tion test(RAMAT)was administered at 30 to 35 days.Lastly,the neuron density in the CA_1 subfield of the rats' hip- pocampi(ND_(CAI)was measured with Nissl staining.Results R_(L/R)and GRW in the HIBD group were significantly lower than in the control group(P＜0.01),while R_(L/R)was increased in the HBO and HBA groups,especially in the HBO group(P＜0.01),although there was no significant difference in GRW between the groups.Compared with the control group,A_(CH)cells were increased and ND_(CAI)was decreased in the HIBD group(P＜0.01),while A_(CH)cells were decreased and ND_(CAI)was elevated in the HBO group in comparison with the HIBD group(P＜0.01).There was no change in A_(CH)cells or ND_(CAI)in the HBA group.The RAMAT results for the HIBD group,including the time to find the arms baited with water,average times of working errors and reference memory errors,were significantly high- er than those of the control group,while these values for the HBO group were obviously lower than for the HIBD group,and there was no change for the HBA group(P＞0.05).Conclusion HBO therapy might increase the re- covery of learning and memory function by attenuating HIBD in neonatal rats.