Spillover of glutamate onto synaptic AMPA receptors enhances fast transmission at a cerebellar synapse
Spillover of glutamate onto synaptic AMPA receptors enhances fast transmission at a cerebellar synapse
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DOI：
10.1016/s0896-6273(02)00787-0
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发表时间：
2002-08-01
期刊：
影响因子：
16.2
通讯作者：
Silver, RA
中科院分区：
文献类型：
--
作者：
DiGregorio, DA;Nusser, Z;Silver, RA
谷氨酸从突触间隙的扩散可以激活高亲和力受体，但不被认为有助于快速AMPA受体介导的传递。在这里，我们表明，单一的AMPA受体EPSC在小脑苔藓纤维颗粒细胞连接介导的直接释放谷氨酸和快速扩散的谷氨酸从邻近的突触。免疫金定位显示AMPA受体仅位于突触后密度，表明突触接触之间发生谷氨酸溢出。溢出电流贡献了一半的突触电荷，并表现出很小的试验间变异性。我们建议，溢出谷氨酸提高传输效率，通过增加的幅度和持续时间的EPSP和减少所产生的波动的概率性质的发射器释放。
Diffusion of glutamate from the synaptic cleft can activate high-affinity receptors, but is not thought to contribute to fast AMPA receptor-mediated transmission. Here, we show that single AMPA receptor EPSCs at the cerebellar mossy fiber-granule cell connection are mediated by both direct release of glutamate and rapid diffusion of glutamate from neighboring synapses. Immunogold localization revealed that AMPA receptors are located exclusively in postsynaptic densities, indicating that spillover of glutamate occurs between synaptic contacts. Spillover currents contributed half the synaptic charge and exhibited little trial-to-trial variability. We propose that spillover of glutamate improves transmission efficacy by both increasing the amplitude and duration of the EPSP and reducing fluctuations arising from the probabilistic nature of transmitter release.