低温调节颅脑创伤小胶质细胞活化的神经保护作用及其机制

Inflammatory response plays an important role in the secondary brain injury after traumatic brain injury (TBI); microglia activation is the main sign of intra-cerebral inflammatory response. The neuroprotective effect of post-TBI mild hypothermia has been accepted widely, however, the accurate mechanisms still need to be elucidated. We previously reported that hypothermia could negatively regulate the neural apoptosis via increasing the autophagy, thus improving the prognosis of TBI. However, the effect of hypothermia on microglia is still unclear. We consider that regulation of microglia activation participates in the neuroprotective effect of post-TBI hypothermia, thus ameliorating the secondary brain insult. In the project, we try to validate this hypothesis in three parts: 1. investigate influence of hypothermia on appearance, function and electrophysiology of microglia in the rats suffered from brain fluid percussion injury model and cell strtech injury model with normothermia and hypothermia treatment; 2. explore changes of microglia autophagy and apoptosis and explore the changes of the common key protein between microglia autophagy and microglia activation-mTOR and its related pathway; 3. investigate effect of hypothermia on function of toll-like receptor-4 in microglia and explore changes of MyD88-dependent pathway. Present project could help us preliminarily elucidate the molecular mechanisms of microglia’s participation in the neuroprotective effect of post-TBI mild hypothermia and supply new idea for investigating efficacious neuroprotective methods.

炎症反应在颅脑创伤（TBI）后的继发性损伤起着很重要的作用，其中小胶质细胞的活化是脑内炎症反应的主要标志。低温对TBI的脑保护作用已经得到广泛认可，但是其确切机制尚有待阐明。我们前期研究发现低温能够通过增加自噬从而负性调节神经细胞的凋亡以改善TBI预后，但对小胶质细胞的影响尚未明确。我们认为低温对小胶质细胞活化有调控作用并可能参与了其脑保护作用机制。本项目拟从三个方面验证该假说：1.建立大鼠液压伤模型及小胶质细胞牵张损伤模型研究低温对小胶质细胞形态、功能及电生理活动的影响；2.研究损伤后低温对小胶质细胞自噬和凋亡的影响，探讨小胶质细胞自噬和活化共同关键蛋白mTOR及其相关通路的变化；3.研究低温对小胶质细胞Toll样受体-4功能的影响，探讨MyD88依赖途径相关蛋白的变化。该研究将初步阐明小胶质细胞参与TBI后低温脑保护作用的分子机制，为探讨有效的神经保护方法提供了新思路。

炎症反应在颅脑创伤（TBI）后的继发性损伤起着很重要的作用，其中小胶质细胞的活化是脑内炎症反应的主要标志。前期研究已证实低温能够通过上调自噬以负性调节损伤区域凋亡，从而改善颅脑创伤预后。本研究使用了大鼠液压冲击颅脑损伤模型，观察了低温对外伤后小胶质细胞自噬相关蛋白及凋亡相关蛋白的影响；利用自噬抑制剂观察了大鼠小胶质细胞自噬和凋亡的变化，探讨了其相互作用；检测了小胶质细胞TLR4受体及依赖MyD88途径上相关蛋白的含量变化，观察了低温对创伤后小胶质细胞的形态、功能以及小胶质细胞特异标记蛋白Iba-1的含量的影响，研究了创伤后低温对小胶质细胞的作用。本研究还初步探索了生酮饮食在颅脑外伤后的神经保护作用，使用了大鼠液压冲击重复性轻度颅脑损伤模型，检测了生酮饮食对外伤后脑内代谢组学相关变化的影响，观察了外伤后生酮饮食对小胶质细胞功能和自噬的作用。本研究还使用了小胶质细胞体外牵张损伤模型，初步探索了外伤后小胶质细胞内microRNA的变化。本研究为进一步探寻低温脑保护的可能机制提供了新的思路。