Microglia are important for brain homeostasis and immunity, but their role in regulating vigilance remains unclear. We employed genetic, physiological, and metabolomic methods to examine microglial involvement in the regulation of wakefulness and sleep. Microglial depletion decreased stable nighttime wakefulness in mice by increasing transitions between wakefulness and non-rapid eye movement (NREM) sleep. Metabolomic analysis revealed that the sleep-wake behavior closely correlated with diurnal variation of the brain ceramide, which disappeared in microglia-depleted mice. Ceramide preferentially influenced microglia in the thalamic reticular nucleus (TRN), and local depletion of TRN microglia produced similar impaired wakefulness. Chemogenetic manipulations of anterior TRN neurons showed that they regulated transitions between wakefulness and NREM sleep. Their firing capacity was suppressed by both microglial depletion and added ceramide. In microglia-depleted mice, activating anterior TRN neurons or inhibiting ceramide production both restored stable wakefulness. These findings demonstrate that microglia can modulate stable wakefulness through anterior TRN neurons via ceramide signaling.

小胶质细胞对大脑稳态和免疫很重要，但它们在调节警惕性方面的作用尚不清楚。我们采用遗传、生理和代谢组学方法来检查小胶质细胞参与调节觉醒和睡眠。小胶质细胞耗竭通过增加清醒和非快速眼动 (NREM) 睡眠之间的转换来降低小鼠夜间稳定的清醒。代谢组学分析显示，睡眠-觉醒行为与脑神经酰胺的昼夜变化密切相关，而神经酰胺在小胶质细胞耗尽的小鼠中消失了。神经酰胺优先影响丘脑网状核 (TRN) 中的小胶质细胞，并且 TRN 小胶质细胞的局部消耗产生了类似的觉醒障碍。前 TRN 神经元的化学遗传学操作表明它们调节清醒和 NREM 睡眠之间的转换。它们的发射能力受到小胶质细胞耗竭和添加神经酰胺的抑制。在小胶质细胞耗尽的小鼠中，激活前 TRN 神经元或抑制神经酰胺的产生都可以恢复稳定的清醒状态。这些发现表明小胶质细胞可以通过神经酰胺信号通过前 TRN 神经元调节稳定的觉醒。