初级纤毛介导Hedgehog通路调控星形胶质细胞极化在运动训练改善慢性脑低灌注大鼠认知功能中的作用机制

White matter injury is the main cause of cognitive impairment caused by chronic cerebral hypoperfusion (CCH), and clearance of myelin debris is the key to white matter repair. Astrocytes are essential for myelin debris clearance. Recently, they have been found to have pro-inflammatory and anti-inflammatory polarization phenotypes. The Hedgehog (Hh) pathway, which is mediated by primary cilia, is involved in its polarization regulation, but the specific mechanism is unknown. Our previous research found that physical exercise can promote white matter repair and improve cognition in CCH rats; Pre-experiments have shown that physical exercise reduced the activation of pro-inflammatory astrocytes, enhanced the myelin debris clearance, and up-regulated the expression of primary cilia-associated proteins. Based on this, we hypothesized that physical exercise may activate Hh pathway through primary cilia, thereby regulating astrocyte phenotypic polarization, promoting myelin debris clearance and white matter repair, ultimately improving cognitive impairment caused by CCH. In this study, the CCH model is established, and the immunoelectron microscopy, gene expression regulation and other methods are used through in vitro and in vivo experiments to observe the effects of physical exercise on astrocytes phenotypic polarization and myelin debris clearance, and further to clarify the role of primary cilia and Hh signaling pathway. The results provide an experimental basis for elucidating the possible mechanisms of physical exercise induced cognition improvement and optimizing the intervention strategies for CCH induced cognitive impairment.

脑白质损伤是慢性脑低灌注（CCH）致认知障碍的主要原因，而髓鞘碎片清除是脑白质修复的关键。星形胶质细胞对髓鞘碎片清除至关重要，近来发现其存在促炎和抗炎两种极化表型，由初级纤毛介导激活的Hedgehog（Hh）通路参与其极化调控，但具体机制未明。我们前期研究发现，运动训练能够促进脑白质修复，改善CCH大鼠的认知功能；预实验显示，运动训练减少促炎型星形胶质细胞激活，增强髓鞘碎片清除，并上调初级纤毛相关蛋白的表达。据此我们假设，运动训练可能通过初级纤毛激活Hh通路，调节星形胶质细胞表型极化，促进髓鞘碎片清除和脑白质修复，改善CCH致认知障碍。本研究拟建立大鼠CCH模型，采用免疫电镜、基因表达调控等方法，通过体内外实验观察运动训练对星形胶质细胞极化与髓鞘碎片清除的影响，并明确初级纤毛与Hh通路在其中的作用，研究结果为阐明运动训练改善认知障碍的可能机制，及优化CCH致认知障碍的干预策略提供实验依据。

慢性脑低灌注（CCH）与认知障碍密切相关，目前其发病机制尚不完全清楚，且缺乏确切有效的干预手段。研究表明，脑白质损伤是CCH的关键病理特点，髓鞘碎片清除和髓鞘再生对于脑白质修复至关重要。星形胶质细胞参与脑白质的损伤与修复过程，近来研究发现其具有促炎和抗炎两种极化表型，初级纤毛介导的信号传导在星形胶质细胞的分化、细胞周期控制与极化中发挥关键作用。我们前期的研究发现，运动训练能够促进脑白质修复，改善CCH大鼠的认知功能；预实验显示，运动训练减少促炎型星形胶质细胞的激活，并增强髓鞘碎片的清除。本项目在前期的研究基础上，采用Wistar大鼠建立CCH模型，探究运动训练对星形胶质细胞极化与髓鞘碎片清除的影响，并明确初级纤毛在其中的作用及机制。.研究结果发现：①运动训练促进CCH大鼠脑内的髓鞘碎片清除和髓鞘再生，改善CCH大鼠的认知功能；②运动训练诱导星形胶质细胞由神经毒性的促炎A1型向神经保护的抗炎A2表型极化；③运动训练通过调节初级纤毛发生和长度表达诱导星形胶质细胞的表型极化；④与Hedgehog信号通路的信号转导密切相关的MAPKs级联可能参与运动训练调节初级纤毛发生和星形胶质细胞极化的过程。.研究结果表明：运动训练可能通过促进星形胶质细胞初级纤毛的表达和长度恢复，调节MAPKs信号级联的表达，减少ERK和JNK信号通路的磷酸化，进而诱导星形胶质细胞由神经毒性的促炎A1型向神经保护的抗炎A2型极化，增强髓鞘碎片清除和髓鞘再生，促进脑白质修复，最终改善CCH大鼠的认知功能。研究结果为我们在临床上应用运动训练作为安全有效的认知障碍非药物治疗手段提供了理论和实验依据，并对深入认识CCH引起认知障碍的发病机制及优化其干预策略具有重要意义。