Time window characteristics of cultured rat hippocampal neurons subjected to ischemia and reperfusion

Objective: To explore cell death and apoptosis in rat hippocampal neurons at different time points after ischemia, hypoxia and reperfusion injury and to elucidate time window characteristics in ischemia neuronal injury. Methods: Hippocampal neurons were obtained from rat embryo and were cultured in vitro. The ischemia and reperfusion of cultured rat hippocampal neurons were simulated by oxygen-glucose deprivation (OGD) and recovery. OGD at different time points ((0.25) h to (3.0) h) and then the same recovery (24 h) were prepared. Annexin (V-PI) staining and flow cytometry examined neuron death and apoptosis at different time after injury. Results: After OGD and recovery, both necrosis and apoptosis were observed. At different times after OGD, there were statistically significant differences in neuron necrosis rate (P<(0.05)), but not in apoptosis rate (P>(0.05)). At recovery, survival rate of hippocampal neurons further decreased while apoptosis rate increased. Furthermore, apoptosis rates of different time differed greatly (P<(0.05)). Apoptosis rate gradually increased with significant difference among those of different time points (P<(0.05)). However, 2 h after ischemia, apoptosis rate decreased markedly. Conclusions: Apoptosis is an important pathway of delayed neuron death. The therapeutic time window should be within 2 h after cerebral ischemia and hypoxia.