Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany; Georg August University, School of Science, 37073 Göttingen, Germany.
Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.
Cell Rep. 2020 Mar 17;30(11):3632-3643.e8. doi: 10.1016/j.celrep.2020.02.083.
Although similar in molecular composition, synapses can exhibit strikingly distinct functional transmitter release and plasticity characteristics. To determine whether ultrastructural differences co-define this functional heterogeneity, we combine hippocampal organotypic slice cultures, high-pressure freezing, freeze substitution, and 3D-electron tomography to compare two functionally distinct synapses: hippocampal Schaffer collateral and mossy fiber synapses. We find that mossy fiber synapses, which exhibit a lower release probability and stronger short-term facilitation than Schaffer collateral synapses, harbor lower numbers of docked synaptic vesicles at active zones and a second pool of possibly tethered vesicles in their vicinity. Our data indicate that differences in the ratio of docked versus tethered vesicles at active zones contribute to distinct functional characteristics of synapses.
尽管在分子组成上相似，但突触可以表现出明显不同的功能递质释放和可塑性特征。为了确定超微结构差异是否共同定义了这种功能异质性，我们结合海马器官型切片培养、高压冷冻、冷冻替代和 3D 电子断层扫描来比较两种功能上不同的突触：海马沙尔夫侧枝和苔藓纤维突触。我们发现，与沙尔夫侧枝突触相比，苔藓纤维突触具有较低的释放概率和更强的短期易化作用，其活性区的停靠突触小泡数量较少，附近可能有第二池的束缚小泡。我们的数据表明，活性区停靠与束缚小泡的比例差异有助于突触的不同功能特征。
