Microglia are critical nervous system-specific cells influencing brain development, maintenance of the neural environment, response to injury, and repair. They contribute to neuronal proliferation and differentiation, pruning of dying neurons, synaptic remodeling and clearance of debris and aberrant proteins. Colonization of the brain occurs during gestation with an expansion following birth with localization stimulated by programmed neuronal death, synaptic pruning, and axonal degeneration. Changes in microglia phenotype relate to cellular processes including specific neurotransmitter, pattern recognition, or immune-related receptor activation. Upon activation, microglia cells have the capacity to release a number of substances, e.g., cytokines, chemokines, nitric oxide, and reactive oxygen species, which could be detrimental or beneficial to the surrounding cells. With aging, microglia shift their morphology and may display diminished capacity for normal functions related to migration, clearance, and the ability to shift from a pro-inflammatory to an anti-inflammatory state to regulate injury and repair. This shift in microglia potentially contributes to increased susceptibility and neurodegeneration as a function of age. In the current review, information is provided on the colonization of the brain by microglia, the expression of various pattern recognition receptors to regulate migration and phagocytosis, and the shift in related functions that occur in normal aging.

中文翻译：

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发育和衰老过程中的小胶质细胞。


小胶质细胞是重要的神经系统特异性细胞，影响大脑发育、神经环境的维持、损伤反应和修复。它们有助于神经元增殖和分化、垂死神经元的修剪、突触重塑以及碎片和异常蛋白质的清除。大脑的定植发生在妊娠期间，出生后会扩张，并受到程序性神经元死亡、突触修剪和轴突变性的刺激而进行定位。小胶质细胞表型的变化与细胞过程有关，包括特定的神经递质、模式识别或免疫相关受体激活。激活后，小胶质细胞有能力释放多种物质，例如细胞因子、趋化因子、一氧化氮和活性氧，这些物质可能对周围细胞有害或有益。随着衰老，小胶质细胞的形态发生变化，并且可能表现出与迁移、清除相关的正常功能能力下降，以及从促炎状态转变为抗炎状态以调节损伤和修复的能力。小胶质细胞的这种转变可能会随着年龄的增长而增加易感性和神经退行性变。在当前的综述中，提供了有关小胶质细胞在大脑中的定植、调节迁移和吞噬作用的各种模式识别受体的表达以及正常衰老中发生的相关功能的转变的信息。