Acute brain slices represent a workhorse model for studying the central nervous system (CNS) from nanoscale events to complex circuits. While slice preparation inherently involves tissue damage, it is unclear how microglia, the main immune cells and damage sensors of the CNS react to this injury and shape neuronal activity ex vivo. To this end, we investigated microglial phenotypes and contribution to network organization and functioning in acute brain slices. We reveal time-dependent microglial phenotype changes influenced by complex extracellular ATP dynamics through P2Y12R and CX3CR1 signalling, which is sustained for hours in ex vivo mouse brain slices. Downregulation of P2Y12R and changes of microglia-neuron interactions occur in line with alterations in the number of excitatory and inhibitory synapses over time. Importantly, functional microglia modulate synapse sprouting, while microglial dysfunction results in markedly impaired ripple activity both ex vivo and in vivo. Collectively, our data suggest that microglia are modulators of complex neuronal networks with important roles to maintain neuronal network integrity and activity. We suggest that slice preparation can be used to model time-dependent changes of microglia-neuron interactions to reveal how microglia shape neuronal circuits in physiological and pathological conditions.

急性脑切片代表了研究中枢神经系统（CNS）（从纳米级事件到复杂电路）的主力模型。虽然切片制备本质上涉及组织损伤，但尚不清楚小胶质细胞、中枢神经系统的主要免疫细胞和损伤传感器如何对这种损伤做出反应并在体外塑造神经元活动。为此，我们研究了急性脑切片中的小胶质细胞表型以及对网络组织和功能的贡献。我们通过 P2Y12R 和 CX3CR1 信号传导揭示了复杂的细胞外 ATP 动力学影响的时间依赖性小胶质细胞表型变化，这种变化在离体小鼠脑切片中持续数小时。随着时间的推移，P2Y12R 的下调和小胶质细胞-神经元相互作用的变化与兴奋性和抑制性突触数量的变化一致。重要的是，功能性小胶质细胞调节突触萌发，而小胶质细胞功能障碍会导致离体和体内波纹活性显着受损。总的来说，我们的数据表明小胶质细胞是复杂神经元网络的调节剂，在维持神经元网络完整性和活性方面发挥着重要作用。我们建议切片制备可用于模拟小胶质细胞-神经元相互作用的时间依赖性变化，以揭示小胶质细胞如何在生理和病理条件下塑造神经元回路。