Support Cells Help Keep the Body's Clock on Time by Using Glutamate Signals in the Brain's Timekeeping Center

SCN astrocytes may actively influence circadian rhythms by regulating neuron activity during nighttime.

• The suprachiasmatic nucleus (SCN) of the hypothalamus consists of both neurons and astrocytes, each playing distinct roles in circadian timing.
• Neurons are metabolically active during the daytime, while astrocytes are active at night, affecting the overall function of the SCN.
• Astrocytes suppress the activity of SCN neurons by controlling levels of glutamate, a key signaling molecule.
• Specific pre-synaptic NMDA receptors in dorsal SCN neurons are involved in sensing astrocytic glutamatergic signals.
• Genetic reprogramming of intracellular clocks in SCN astrocytes can alter circadian behavioral rhythms in adult mice.
• The interaction between astrocytes and neurons is crucial for maintaining the SCN's timekeeping function.

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