Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
Nat Neurosci. 2012 Jun 10;15(7):988-97. doi: 10.1038/nn.3137.
Cortical synapses have structural, molecular and functional heterogeneity; our knowledge regarding the relationship between their ultrastructural and functional parameters is still fragmented. Here we asked how the neurotransmitter release probability and presynaptic [Ca(2+)] transients relate to the ultrastructure of rat hippocampal glutamatergic axon terminals. Two-photon Ca(2+) imaging-derived optical quantal analysis and correlated electron microscopic reconstructions revealed a tight correlation between the release probability and the active-zone area. Peak amplitude of [Ca(2+)] transients in single boutons also positively correlated with the active-zone area. Freeze-fracture immunogold labeling revealed that the voltage-gated calcium channel subunit Cav2.1 and the presynaptic protein Rim1/2 are confined to the active zone and their numbers scale linearly with the active-zone area. Gold particles labeling Cav2.1 were nonrandomly distributed in the active zones. Our results demonstrate that the numbers of several active-zone proteins, including presynaptic calcium channels, as well as the number of docked vesicles and the release probability, scale linearly with the active-zone area.
皮质突触具有结构、分子和功能的异质性；我们对于它们超微结构和功能参数之间关系的了解仍然是零散的。在这里，我们想知道神经递质释放概率和突触前[Ca(2+)]瞬变与大鼠海马谷氨酸能轴突末梢的超微结构有何关系。双光子 Ca(2+)成像衍生的光量子分析和相关的电子显微镜重建显示，释放概率与活性区面积之间存在紧密的相关性。单囊泡中[Ca(2+)]瞬变的峰值幅度也与活性区面积呈正相关。冷冻断裂免疫金标记显示，电压门控钙通道亚基 Cav2.1 和突触前蛋白 Rim1/2 局限于活性区，其数量与活性区面积呈线性关系。标记 Cav2.1 的金颗粒在活性区呈非随机分布。我们的结果表明，包括突触前钙通道在内的几种活性区蛋白的数量，以及停靠囊泡的数量和释放概率，与活性区面积呈线性关系。
