目的·探讨小胶质细胞瞬时受体电位香草酸亚型1（transient receptor potential vanilloid 1，TRPV1）对载脂蛋白E4（apolipoprotein E4，ApoE4）相关帕金森病（Parkinson's disease，PD）病理进程的调控作用。方法·繁育APOE3/Trpv1^flox/flox（E3/Trpv1^fl/fl）、APOE4/Trpv1^flox/flox（E4/Trpv1^fl/fl）和小胶质细胞特异性Trpv1敲除的Cx3cr1^Cre（E4/Trpv1^MGKO）小鼠，在上述小鼠黑质致密部（substantia nigra pars compacta，SNpc）注射人A53T α-突触核蛋白（AAV-hα-syn）。同样方法在E3/Trpv1^fl/fl小鼠的SNpc注射AAV-GFP（green fluorescent protein）作为对照。注射30 d后，采用旷场实验、牵引力实验、爬杆实验、转棒实验和悬尾实验分析小鼠的运动协调能力和肌肉耐力，采用莫里斯水迷宫实验检测小鼠的空间学习与记忆能力。采用免疫荧光技术，使用酪氨酸羟化酶（tyrosine hydroxylase，TH）和磷酸化Ser129 α-突触核蛋白［p-α-syn（Ser129）］抗体检测小鼠SNpc多巴胺能神经元存活和病理性α-syn沉积情况，使用离子钙结合接头分子1（ionized calcium-binding adapter molecule 1，Iba1）和p-α-syn（Ser129）抗体检测小鼠中脑小胶质细胞的吞噬功能，并采用BODIPY 493/503染色观察小胶质细胞、神经元和星形胶质细胞中脂滴积聚情况。结果·牵引力测试结果显示，E4/Trpv1^MGKO（AAV-hα-syn）小鼠与E4/Trpv1^fl/fl（AAV-hα-syn）小鼠相比握力无差异；但其在旷场中的平均速度和行进距离增加，爬杆实验的翻转所需时间（t_turn）及下降时间（t_LA）显著延长，转棒实验的停留潜伏期缩短，悬尾实验中表现出更强的张力障碍姿势，显示出E4/Trpv1^MGKO小鼠运动功能障碍加重；莫里斯水迷宫实验中E4/Trpv1^MGKO小鼠逃避潜伏期明显延长，在目标象限行进距离占比减少，显示小胶质细胞TRPV1缺失显著影响ApoE4相关PD小鼠的空间学习能力。免疫荧光检测显示，E4/Trpv1^MGKO（AAV-hα-syn）小鼠SNpc多巴胺能神经元丧失加剧，p-α-syn沉积增多。并且其中脑小胶质细胞吞噬能力增强，脂滴积累增加，但小胶质细胞TRPV1缺失并未加剧小鼠星形胶质细胞和神经元中的脂滴积累。结论·小胶质细胞TRPV1缺失加速了ApoE4介导的PD病理进程，破坏了小胶质细胞的脂质代谢稳态。

Objective ·To investigate the regulatory role of microglial transient receptor potential vanilloid 1 (TRPV1) in the pathological progression of apolipoprotein E4 (ApoE4)-associated Parkinson's disease (PD). Methods ·APOE3/Trpv1^flox/flox (E3/Trpv1^fl/fl), APOE4/Trpv1^flox/flox (E4/Trpv1^fl/fl), and microglia-specific Trpv1 knockout Cx3cr1^Cre (E4/Trpv1^MGKO) mice were bred and injected with human A53T α-synuclein (AAV-hα-syn) into the substantia nigra pars compacta (SNpc). AAV-GFP was injected into the SNpc of E3/Trpv1^fl/fl mice as a control. After 30 days, motor function, coordination, and muscle endurance were evaluated using the open field test, traction test, pole test, rotarod test, and tail suspension test, while spatial learning and memory were assessed using the Morris water maze test. The immunofluorescence technique was used. The survival of dopaminergic neurons and pathological α-syn deposition in the SNpc were detected using tyrosine hydroxylase (TH) and phosphorylated Ser129 α-synuclein [p-α-syn (Ser129)] antibodies. The phagocytosis of microglia in the midbrain was detected using ionized calcium-binding adapter molecule 1 (Iba1) co-staining with p-α-syn (Ser129), while the accumulation of lipid droplets in microglia, neurons, and astrocytes was observed by BODIPY 493/503 staining. Results ·In traction tests, E4/Trpv1^MGKO(AAV-hα-syn) mice showed no significant differences in grip strength compared to E4/Trpv1^fl/fl(AAV-hα-syn) group. However, these mice exhibited increased mean velocity and total distance in open field tests, significantly prolonged time to turn (t_turn) and time for lateral ambulation (t_LA) in pole tests, shortened latency to remain on the rotarod, and induced stronger dystonic postures during tail suspension, indicating aggravated motor dysfunction in ApoE4-associated PD mice. The Morris water maze demonstrated that E4/Trpv1^MGKO(AAV-hα-syn) mice exhibited significantly prolonged escape latency and a reduced proportion of travel distance in the target quadrant, indicating that TRPV1 deficiency in microglia significantly impaired spatial learning ability in ApoE4-associated PD mice. Immunofluorescence revealed that the loss of dopaminergic neurons in the SNpc was aggravated in E4/Trpv1^MGKO(AAV-hα-syn) mice, and the p-α-syn deposition in the SNpc was increased. The phagocytosis of microglia in the mesencephalon was enhanced, and the accumulation of lipid droplets was increased. However, the deficiency of TRPV1 in microglia did not aggravate the accumulation of lipid droplets in astrocytes and neurons. Conclusion ·TRPV1 deficiency in microglia accelerates the pathological progression of ApoE4-associated PD and disrupts lipid metabolic homeostasis in microglia.