Effects Of Different Kinds Of Oxygen Therapies On The Fetal Rats Following Hypoxia-ischemic Brain Damage

Objective:To evaluate the effects of different kinds of oxygen therapies on the fetal rats following hypoxia-ischemic brain damage.Methods:Twenty-five 17-day-old pregnant rats were randomized into two groups including twenty rats were hypoxia-ischemic group and the rest five rats were sham operated group.A intrauterine hypoxia-ischemic model was established by clamping both of the uterine artery for 15 minutes of the hypoxia-ischemic group rats.The sham operated group rats did not clamped the uterine artery.Then twenty hypoxia-ischemic rats were randomized into four groups including non-given oxygen group,low-concentration interrupted oxygen given group,high-concentration pulse oxygen given group and low-concentration persistent oxygen given group.Each group had five pregnant rats.In the day of pregnant for 18-day-old,low-concentration interrupted oxygen given group was given oxygen which oxygen concentration about 37%,30 minutes one time,three times daily for three days;high-concentration pulse oxygen given group oxygen concentration about 84%,after 15 minutes oxygen therapy stop for 5 minutes,then renew 15 minutes oxygen,once for one day for three days;low-concentration persistent oxygen given group oxygen concentration about 37%,8 hours continuous for one day for three days.In the day of pregnant for 21-day-old,all pregnant rats received caesarean section and the obtained fetal rats were killed by cutting off their heads.The HE stain for pathology and the levels iNOS in cerebral tissue of the obtained fetal rats were determined respectively.Results:(1)Pathology in the cerebral tissue:All of the cerebral tissue of non-given oxygen group appeared angio-hyperemia,confused structure,part of the neuron swelling,central type Nissl body dissolved,part of the nucleus pycnosis,nucleolus diminution or even disappear,colloid cell nodule formed. About the low-concentration interrupted oxygen given and high-concentration pulse oxygen given group,cerebral tissues had clear layer,no obviously degeneration or necrosis.But the cerebral cortex of low-concentration persistent oxygen given group appeared angio-hyperemia,confused structure, the same as the non-given oxygen group.(2)Levels of iNOS in the cerebral tissue of fetal rats:non-given oxygen group(39.78±10.02)%significantly higher than those of the sham operated group(19.69±7.21)%.(P＜0.05).After oxygen intervened,about the low-concentration interrupted oxygen given group(22.78±8.10)%and high-concentration pulse oxygen given group(24.54±8.11)%,the levels of iNOS decreased significantly than those of the non-given oxygen group and the low-concentration persistent oxygen given group(56.92±10.74)% respectively(P＜0.05);but no statistics difference compared to the sham operated group respectively(P＞0.05);between low-concentration interrupted oxygen given group and high-concentration pulse oxygen given group had no statistics difference(P＞0.05).The levels of iNOS increased significantly for the low-concentration persistent oxygen given group than those of the non-given oxygen group(P＜0.05).Conclusion:(1)In the cerebral tissue of fetal rats following intrauterine hypoxiaischemic, the structure of cerebral cortex were confused,neuron presented degenerated,colloid cell nodule were formed.Levels of iNOS increased significantly,showed the intrauterine hypoxia and ischemic in the gestation period could cause brain damage to fetal rats.(2)Low-concentration interrupted and high-concentration pulse oxygen therapy could protect cerebral tissue from intrauterine hypoxia-ischemic brain damage,but low-concentration persistent oxygen therapy might aggravate the brain damage.