纯氧与空气环境复苏对低氧新生大鼠大脑皮质神经元凋亡的影响

目的应用无创性低氧动物模型,比较纯氧环境(pure oxygen environment,POE,100%氧)与空气环境(room air environment,RAE,21%氧)复苏对低氧新生大鼠大脑皮质神经元凋亡的影响。方法 30只SpragueDawley(SD)7日龄乳鼠在建立低氧2.5 h模型后,分别于纯氧环境与空气环境中进行复苏。实验分为正常对照组(无预缺氧和复氧实验,n=10)、纯氧环境组(POE,n=10)和空气环境组(RAE,n=10),依复苏后时间点每组又分为24 h组和72 h组,每亚组5只。按时间点取各组乳鼠大脑皮质行尼氏体染色、原位末端标记(TUNEL)技术、图像分析和透射电镜观察神经元凋亡。结果与正常对照组相比,低氧乳鼠复氧后各组大脑皮质内锥体层均可见散在的、单个的、成群的或2～4个排列成串的凋亡锥体神经元,细胞凋亡现象RAE 72 h组最明显,POE 72 h组凋亡细胞个数和面密度都较RAE 72 h组少(P0.01)。电镜下RAE 72 h组类似凋亡细胞核也较其他各组多见。结论在本动物模型POE复苏较RAE复苏早期可更能减少细胞凋亡,缓解低氧致神经元的损伤,表明纯氧早期对新生儿低氧性脑损伤有一定的保护作用。

Effects of Resuscitation in 100% Oxygen Environment or Room Air Environment on the Apoptosis in Cerebral Cortical Neurons of Hypoxic Neonatal Rats

Objective To evaluate the effects of resuscitation in a pure oxygen environment（POE,100% oxygen） or a room air environment（RAE,21% oxygen） on the apoptosis in cerebral cortical neurons using a non-traumatic hypoxic neonatal rats model.Methods 20 of 30 Sprague-Dawley neonatal rat hypoxic models aged 7 days were established for 2.5 h.30 pups were then divided into normal control group（without pre-hypoxia and reoxygenation,n = 10）,group with pure oxygen environment resuscitation（n = 10）,group with room air environment resuscitation（n = 10） and each group was divided again i.e.24 h subgroup and 72 h subgroup（n = 5）.According to the planned time points the pups were sacrificed and the brain was removed at 24 h and 72 h after treatment,respectively.The cerebral cortex tissue samples were prepared for examination of apoptosis using Nissl staining,in situ TUNEL staining,color image analysis system and transmission electron microscopy.Results As compared with those in the normal control group,sporadic single cell or clusters of 2 ～ 4 cells in a row arranged apoptotic pyramidal cells were encountered in inner pyramidal layer of the cerebral cortex in both resuscitation groups.Apoptosis mostly appeared in the RAE 72 h group.At 72 h after resuscitation with POE,the number and area density of apoptotic cells were significantly lower than those in the RAE 72 h group（P 0.01）.Under transmission electron microscope,in the RAE 72 h group apoptosis-like nuclei were seen morefrequently than in other groups.Conclusions The results indicate that the POE resuscitation causes less cell apoptosis and milder cerebral damage than the RAE resuscitation in the non-traumatic hypoxic neonatal rat model.Therefore,the protective effect of the POE resuscitation on cerebral damage of hypoxic neonatal rats is superior to the RAE resuscitation.