亚甲蓝在PI3K/AKT信号通路中保护慢性脑低灌注致神经血管单元损害中的作用

Chronic cerebral hypoperfusion(CCH) contributes to the development of cognitive impairment， while the underlying mechanism remains largely unknown. Methylene Blue (MB) has neuroprotective effect against cognitive impairment during CCH. But the mechanism of MB on it was still unclear. Our preliminary study showed that MB treatment attenuated the damage of neurovascular unit(NVU) after chronic cerebral hypoperfusion and the protect effect can be significantly impaired by blockage of the PI3K/AKT signal pathway. Detailed understanding of role of PI3K/AKT signal pathway in NCV protection and how as well as when MB active PI3K/AKT signal pathway is critical for future therapeutic strategies. In the present study, we will determine the NVU lesion and related PI3K/AKT signal pathway activation in CCH rat. Simultaneously, the remodeling of NVU after MB treatment will be observed. Using the techniques of multi-modality MRI combined with techniques of molecular biology, we aimed to obtain the role of PI3K/AKT signal pathway in the remodeling of NVU after CCH and find out the therapeutic target for MB treatment in cognitive dysfunction.

慢性低灌注是引起认知障碍的高危因素，但其导致认知损害的机制知之甚少。亚甲蓝可以改善慢性脑低灌注后的认知功能损害，其具体作用环节尚不明确。我们的预实验发现PI3K/AKT信号通路阻断剂能减弱亚甲蓝对慢性脑低灌注后血管神经单元的保护效应，提示亚甲蓝的保护作用可能是通过PI3K/AKT信号通路发挥作用。为了验证其具体调节机制，我们通过大鼠双侧颈总动脉结扎模型，采用多模态功能磁共振技术、real time PCR、Western blot、免疫荧光标记等手段，从分子到动物整体水平，从结构到功能变化多层面探讨慢性脑低灌注后亚甲蓝对PI3K/AKT信号通路的具体调控机制及其在保护神经血管单元损伤中的作用。本研究以血管神经单元为治疗靶点，从PI3K/AKT信号通路调控血管神经单元重塑这个新视点，揭示亚甲蓝对慢性低灌注导致神经血管单元损害的内源性保护机制的调控机理，为血管性痴呆防治提供新的思路。

慢性脑低灌注(CCH)是引起认知障碍的高危因素，但其导致认知损害的机制知之甚少。亚甲蓝(MB)可以改善慢性脑低灌注后的认知功能损害，其具体作用环节尚不明确。本项目主要研究了MB治疗前后CCH对大鼠脑内PI3K/AKT信号通路的影响，同时探讨了亚甲蓝激活PI3K/AKT信号通路对CCH后神经血管单元(NVU)的保护作用及其调控机制。我们的研究结果证实了MB对CCH后认知损伤和NVU的保护作用，且其保护作用与PI3K/AKT信号通路有关：应用MB后CCH大鼠水迷宫试验表现明显改善，而应用PI3K/AKT信号通路抑制剂LY294002后MB的效应明显减弱；每日使用MB可以降低血脑屏障的通透性，改善脑血流(CBF)，部分恢复神经元活性，上调p-Akt和t-Akt的表达，增加CCH后CA1区神经元密度，而应用LY294002后，CBF、PI3K的表达以及神经元密度均明显降低。总的来说，本项目证实MB能够通过促进神经血管单元的结构与功能保护作用，改善了CCH后实验大鼠的认知功能障碍。