目的　探讨新生动物脑缺氧缺血 (HI)后迟发性细胞死亡是否存在细胞凋亡 ;分析不同检测手段的敏感性与特异性。方法　在建立新生大鼠脑HI损伤标准动物模型基础上,采用脑组织病理学HE染色光镜观察、透射电镜、原位末端标记 (ISEL)及DNA电泳等分别对HI后不同时间点的实验侧脑皮质、海马回中凋亡细胞的形态、特点等进行观察和比较。结果　光镜、电镜下显示实验侧脑皮质及海马神经元皱缩、染色质凝集并出现凋亡小体,ISEL及DNA电泳证实有裂解DNA存在。且发现脑皮质及海马回凋亡性细胞死亡通常自HI后 6～12h开始,2 4h达高峰。结论　缺氧缺血可引起新生动物脑细胞凋亡。在脑HI迟发性损伤中不仅存在坏死,而且存在着复杂的细胞凋亡过程。不同的检测手段均具有一定的局限性 ,只有结合多种方法进行检测 ,才能正确判定凋亡细胞的存在。

Objective To determine whether or not apoptosis occurs in the delayed cell death following hypoxic ischemic injury, and assess the sensibility and specificity of various techniques. Methods Using HE staining and electromicroscopic technique, in situ end labeling (ISEL) and DNA electrophoresis, we observed the histological features of apoptotic cells in the cerebral cortex and hippocampus, and compared the ipsilateral hemisphere at various time points following hypoxic ischemia (HI) with that of the sham group. Results In the cerebral cortex and hippocampus at the ipsilateral hemisphere in neonatal rat models of HI, light and electronic microscopy exhibited cell shrinkage, chromatin condensation, and apoptotic bodies. ISEL and DNA electrophoresis also provided evidence of DNA fragmentation. It was found that apoptotic cell death generally began 6～12 h after the initiating insult, and reached the peak at 24 h in the cortex and hippocampus. Conclusions Cerebral HI can induce neuronal apoptosis in neonatal rats. Apoptosis is mainly involved in the delayed cell death following hypoxic ischemic injury except for the existence of necrosis. Apoptosis appears to be a major form of delayed cell death during the selective neuronal loss following hypoxic ischemic injury. Owing to the limitation of different techniques, it is necessary to adopt several ways to determine the existence of apoptosis.