Department of Neurobiology, University of Alabama at Birmingham, Birmingham, United States.
Department of Molecular and Cellular Biology, University of California Berkeley, Berkeley, United States.
Elife. 2020 Jun 30;9:e54125. doi: 10.7554/eLife.54125.
Parvalbumin-expressing interneurons (PVs) in the dentate gyrus provide activity-dependent regulation of adult neurogenesis as well as maintain inhibitory control of mature neurons. In mature neurons, PVs evoke GABA postsynaptic currents (GPSCs) with fast rise and decay phases that allow precise control of spike timing, yet synaptic currents with fast kinetics do not appear in adult-born neurons until several weeks after cell birth. Here we used mouse hippocampal slices to address how PVs signal to newborn neurons prior to the appearance of fast GPSCs. Whereas PV-evoked currents in mature neurons exhibit hallmark fast rise and decay phases, newborn neurons display slow GPSCs with characteristics of spillover signaling. We also unmasked slow spillover currents in mature neurons in the absence of fast GPSCs. Our results suggest that PVs mediate slow spillover signaling in addition to conventional fast synaptic signaling, and that spillover transmission mediates activity-dependent regulation of early events in adult neurogenesis.
颗粒细胞层表达钙结合蛋白的中间神经元（PVs）为成年神经发生提供活动依赖性调节，同时维持成熟神经元的抑制性控制。在成熟神经元中，PV 引发具有快速上升和下降相的 GABA 突触后电流（GPSCs），从而允许精确控制尖峰定时，然而，直到出生后数周，新生神经元才出现具有快速动力学的突触电流。在这里，我们使用小鼠海马切片来解决在快速 GPSCs 出现之前，PV 如何向新生神经元发出信号的问题。虽然成熟神经元中 PV 引发的电流表现出标志性的快速上升和下降相，但新生神经元显示出具有溢出信号特征的缓慢 GPSCs。我们还在没有快速 GPSCs 的情况下揭示了成熟神经元中的缓慢溢出电流。我们的结果表明，PV 除了传统的快速突触信号外，还介导缓慢的溢出信号，并且溢出传递介导成年神经发生中早期事件的活动依赖性调节。
