Astrocytes of the suprachiasmatic nucleus (SCN) can regulate sleep-wake cycles in mammals. However, the nature of the information provided by astrocytes to control circadian patterns of behavior is unclear. Neuronal circadian activity across the SCN is organized into spatiotemporal waves that govern seasonal adaptations and timely engagement of behavioral outputs. Here, we show that astrocytes across the mouse SCN exhibit instead a highly uniform, pulse-like nighttime activity. We find that rhythmic astrocytic GABA production via polyamine degradation provides an inhibitory nighttime tone required for SCN circuit synchrony, thereby acting as an internal astrocyte zeitgeber (or "astrozeit"). We further identify synaptic GABA and astrocytic GABA as two key players underpinning coherent spatiotemporal circadian patterns of SCN neuronal activity. In describing a new mechanism by which astrocytes contribute to circadian timekeeping, our work provides a general blueprint for understanding how astrocytes encode temporal information underlying complex behaviors in mammals.

中文翻译：

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有节奏的星形胶质细胞 GABA 产生同步视交叉上核中的神经元昼夜节律计时。


视交叉上核 （SCN） 的星形胶质细胞可以调节哺乳动物的睡眠-觉醒周期。然而，星形胶质细胞为控制昼夜节律行为模式提供的信息的性质尚不清楚。整个 SCN 的神经元昼夜节律活动被组织成时空波，这些时空波控制季节性适应和行为输出的及时参与。在这里，我们表明小鼠 SCN 上的星形胶质细胞表现出高度均匀的脉冲样夜间活动。我们发现，通过多胺降解产生的有节奏的星形胶质细胞 GABA 提供了 SCN 回路同步所需的抑制性夜间音调，从而充当内部星形胶质细胞 zeitgeber（或“astrozeit”）。我们进一步确定突触 GABA 和星形胶质细胞 GABA 是支撑 SCN 神经元活动的连贯时空昼夜节律模式的两个关键参与者。在描述星形胶质细胞促进昼夜节律计时的新机制时，我们的工作为理解星形胶质细胞如何编码哺乳动物复杂行为背后的时间信息提供了一般蓝图。