HIF-1α在异氟烷麻醉致发育期神经凋亡中的作用及信号转导机制

Learning/remembering disabilities due to early exposure to anesthesia is the focus concerned by common population and anesthesiologist. It is documented by animal and cell test that inhalational anesthetic isoflurane can induce developmental neuroapoptosis. But the underlying mechanisms are elusive. Isoflurane can induce elevation of cytosolic calcium and caspase-3 activation during neuron apoptosis. We have found that isoflurane can activate transcription factor HIF-1α when induce cytosolic calcium elevation. Furthermore, our pilot test fount that the apoptosis induced by isoflurane in HIF-1α+/- neuron is much less compared with the HIF-1α+/+ neuron,and the neurodegeneration of isoflurane is closely correlated with nuclear HIF-1α activation. Thus our hypothesis is that cytosolic calcium elevation activates HIF-1α,resulting in caspase-3 activation is the new mechanisms underlying the developmental neurotoxicity of isoflurane. we will set up HIF-1α+/+ and HIF-1α+/- mice and neuron isoflurane anesthesia model, and use RNA interference, laser confocal, calcium image and animal behavior techniques to prove our hypothesis through ion-gene-cell-whole levels. Conclusions from our study will provide new clues and targets to answer the impact of anesthesia on neonates learning/remembering abilities and to provide therapy to post-operation cognition dysfunction.

麻醉药对婴幼儿学习记忆能力的影响一直是广大民众和麻醉医师关注的焦点。动物和细胞实验发现吸入麻醉药异氟烷可致发育期神经凋亡，但具体机制不详。已知异氟烷致神经凋亡时有细胞内钙离子浓度升高和caspase-3活化。我们前期研究显示异氟烷增加细胞内钙的同时激活转录因子HIF-1α。进一步的预实验发现异氟烷在HIF-1α+/-神经元的致凋亡效应较在HIF-1α+/+神经元显著减轻，其致凋亡效应与HIF-1α核内激活明显相关。因此我们推测"细胞内钙增加使HIF-1α持续激活，导致caspase-3活化"是异氟烷致发育期神经凋亡的新机制。我们拟制备HIF-1α+/+和HIF-1α+/-小鼠和神经细胞的异氟烷处理模型，采用RNAi、激光共聚焦、钙离子成像、动物行为学等技术，从离子-基因-细胞-整体层次证明我们的假说。研究结果将为回答麻醉对婴幼儿学习记忆能力的影响以及术后认知功能障碍防治提供新思路和新靶点。

麻醉药对婴幼儿学习记忆能力的影响一直是广大民众和麻醉医师关注的焦点。动物和细胞实验发现吸入麻醉药异氟烷可致发育期神经凋亡，但具体机制不详。已知异氟烷致神经凋亡时有细胞内钙离子浓度升高和caspase-3 活化。我们前期研究显示异氟烷增加细胞内钙的同时激活转录因子 HIF-1α 。进一步的预实验发现异氟烷在HIF-1α +/-神经元的致凋亡效应较在HIF-1α +/+神经元明显减轻，其致凋亡效应与HIF-1α 核内激活明显相关。因此我们推测“细胞内钙增加使 HIF-1α 持续激活，导致 caspase-3活化”是异氟烷致发育期神经凋亡的新机制。我们采用小鼠海马神经元体外培养14-18天后，异氟烷处理（0.4mM，12h）后，采用MTT法和LDH试验检测异氟烷的神经损伤作用，并检测HIF-1α基因表达和转录活性，细胞内钙离子浓度变化以及相应的细胞内信号传递通路的影响，同时我们制备 HIF-1α +/+和 HIF-1α +/-小鼠和神经细胞的异氟烷处理模型，采用RNAi,激光共聚焦，钙离子成像，动物行为学等技术，从离子-基因-细胞-整体层次证明我们的假说。研究结果将为回答麻醉对婴幼儿学习记忆能力的影响以及术后认知功能障碍防治提供新思路和新靶点。