VARIATION IN THE NUMBER, LOCATION AND SIZE OF SYNAPTIC VESICLES PROVIDES AN ANATOMICAL BASIS FOR THE NONUNIFORM PROBABILITY OF RELEASE AT HIPPOCAMPAL CA1 SYNAPSES
VARIATION IN THE NUMBER, LOCATION AND SIZE OF SYNAPTIC VESICLES PROVIDES AN ANATOMICAL BASIS FOR THE NONUNIFORM PROBABILITY OF RELEASE AT HIPPOCAMPAL CA1 SYNAPSES
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DOI：
10.1016/0028-3908(95)00142-s
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发表时间：
1995-11-01
影响因子：
4.7
通讯作者：
SULTAN, P
中科院分区：
文献类型：
--
作者：
HARRIS, KM;SULTAN, P
在海马CA 1区代表性轴突终末的三维重建中测量突触囊泡、突触裂隙和突触后面积。对对接和非对接囊泡进行计数和测量。细刺上的小钮有大约2-6个停靠的囊泡，来自200多个囊泡的池。中型蘑菇状树突棘上的中型终扣包含来自超过450个囊泡的池的约13-16个对接囊泡。一个大的钮扣突触与一个大的蘑菇状树突棘有两簇囊泡，总计超过1000个囊泡。突触后致密物被分成两个离散的区域，在两个小泡簇下，36个停靠的小泡分布在其表面。两个多突触终扣含有超过500个囊泡，在每个终扣上的两个突触后密度中的每一个处观察到2-12个对接囊泡。这种停靠囊泡的非均匀数量为不同大小的海马突触之间发生的非均匀释放概率提供了解剖学基础。此外，每个突触囊泡的体积被确定为重构的突触裂缝的总体积的0.4-5.2%，它们推测释放其内容物到所述突触裂缝中。然而，由于每个囊泡含有超过10倍浓度的谷氨酸，使突触后受体饱和，这些数据也支持这样的假设：即使是单个突触囊泡的释放也会激活所有突触后受体。
Synaptic vesicles, synaptic clefts and postsynaptic areas were measured in three dimensional reconstructions at representative axonal boutons in hippocampal area CA1. Both docked and non-docked vesicles were counted and measured. Small boutons on thin spines had about 2-6 docked vesicles from a pool of more than 200 vesicles. Medium-sized boutons on medium-sized mushroom-shaped dendritic spines contained about 13-16 docked vesicles from a pool of more than 450 vesicles. A large bouton synapsing with a large mushroom-shaped dendritic spine had two clusters of vesicles totaling more than 1000 vesicles. The postsynaptic density was segmented into two discrete zones under the two clusters of vesicles and 36 docked vesicles were distributed over its surfaces. Two multiple-synapse boutons contained more than 500 vesicles with 2-12 docked vesicles observed at each of the two postsynaptic densities on each bouton. This nonuniform number of docked vesicles provides an anatomical basis for the non-uniform probability of release that occurs across hippocampal synapses of different sizes. In addition, the volume of each synaptic vesicle was determined to be 0.4-5.2% of the total volume of the reconstructed synaptic clefts into which they presumably release their contents. However, since each vesicle contains more than 10 times the concentration of glutamate needed to saturate the postsynaptic receptors, these data also support the hypothesis that release of even a single synaptic vesicle will activate all of the postsynaptic receptors.