Zhang Lijuan, Zhang Jinqiang, You Zili
Center for Informational Biology, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China.
Front Cell Neurosci. 2018 Oct 16;12:306. doi: 10.3389/fncel.2018.00306. eCollection 2018.
Major depressive disorder (MDD) is a common emotional cognitive disorder that seriously affects people's physical and mental health and their quality of life. Due to its clinical and etiological heterogeneity, the molecular mechanisms underpinning MDD are complex and they are not fully understood. In addition, the effects of traditional drug therapy are not ideal. However, postmortem and animal studies have shown that overactivated microglia can inhibit neurogenesis in the hippocampus and induce depressive-like behaviors. Nonetheless, the molecular mechanisms by which microglia regulate nerve regeneration and determine depressive-like behaviors remain unclear. As the immune cells of the central nervous system (CNS), microglia could influence neurogenesis through the M1 and M2 subtypes, and these may promote depressive-like behaviors. Microglia may be divided into four main states or phenotypes. Under stress, microglial cells are induced into the M1 type, releasing inflammatory factors and causing neuroinflammatory responses. After the inflammation fades away, microglia shift into the alternative activated M2 phenotypes that play a role in neuroprotection. These activated M2 subtypes consist of M2a, M2b and M2c and their functions are different in the CNS. In this article, we mainly introduce the relationship between microglia and MDD. Importantly, this article elucidates a plausible mechanism by which microglia regulate inflammation and neurogenesis in ameliorating MDD. This could provide a reliable basis for the treatment of MDD in the future.
重度抑郁症（MDD）是一种常见的情绪认知障碍，严重影响人们的身心健康和生活质量。由于其临床和病因的异质性，MDD的分子机制复杂，尚未完全明确。此外，传统药物治疗的效果并不理想。然而，尸检和动物研究表明，过度激活的小胶质细胞可抑制海马体中的神经发生并诱发抑郁样行为。尽管如此，小胶质细胞调节神经再生并决定抑郁样行为的分子机制仍不清楚。作为中枢神经系统（CNS）的免疫细胞，小胶质细胞可通过M1和M2亚型影响神经发生，而这些亚型可能会促进抑郁样行为。小胶质细胞可能分为四种主要状态或表型。在应激状态下，小胶质细胞被诱导为M1型，释放炎症因子并引起神经炎症反应。炎症消退后，小胶质细胞转变为具有神经保护作用的替代性激活M2表型。这些激活的M2亚型包括M2a、M2b和M2c，它们在中枢神经系统中的功能各不相同。在本文中，我们主要介绍小胶质细胞与MDD之间的关系。重要的是，本文阐明了小胶质细胞在改善MDD过程中调节炎症和神经发生的一种合理机制。这可为未来MDD的治疗提供可靠依据。
