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Quantal Fluctuations in Central Mammalian Synapses: Functional Role of Vesicular Docking Sites
Physiological Reviews ( IF 33.6 ) Pub Date : 2017-10-01 , DOI: 10.1152/physrev.00032.2016
Camila Pulido 1 , Alain Marty 1
Affiliation  

Quantal fluctuations are an integral part of synaptic signaling. At the frog neuromuscular junction, Bernard Katz proposed that quantal fluctuations originate at “reactive sites” where specific structures of the presynaptic membrane interact with synaptic vesicles. However, the physical nature of reactive sites has remained unclear, both at the frog neuromuscular junction and at central synapses. Many central synapses, called simple synapses, are small structures containing a single presynaptic active zone and a single postsynaptic density of receptors. Several lines of evidence indicate that simple synapses may release several synaptic vesicles in response to a single action potential. However, in some synapses at least, each release event activates a significant fraction of the postsynaptic receptors, giving rise to a sublinear relation between vesicular release and postsynaptic current. Partial receptor saturation as well as synaptic jitter gives to simple synapse signaling the appearance of a binary process. Recent investigations of simple synapses indicate that the number of released vesicles follows binomial statistics, with a maximum reflecting the number of docking sites present in the active zone. These results suggest that at central synapses, vesicular docking sites represent the reactive sites proposed by Katz. The macromolecular architecture and molecular composition of docking sites are presently investigated with novel combinations of techniques. It is proposed that variations in docking site numbers are central in defining intersynaptic variability and that docking site occupancy is a key parameter regulating short-term synaptic plasticity.

中文翻译:

中央哺乳动物突触的量子波动:水泡停靠站点的功能作用。

量子波动是突触信号的组成部分。在青蛙的神经肌肉连接处,伯纳德·卡茨(Bernard Katz)提出,数量波动起于“反应部位”,在这些部位,突触前膜的特定结构与突触小泡相互作用。然而,无论是在青蛙神经肌肉连接处还是在中央突触处,反应部位的物理性质仍不清楚。许多中央突触,称为简单突触,是包含单个突触前活性区和单个突触后密度受体的小结构。几条证据表明,简单的突触可响应单个动作电位而释放出多个突触小泡。但是,至少在某些突触中,每个释放事件都会激活很大一部分突触后受体,引起囊泡释放与突触后电流之间的亚线性关系。部分受体饱和以及突触抖动使简单的突触发出二元过程的信号。对简单突触的最新研究表明,释放的囊泡数量遵循二项式统计,最大值反映了活动区域中存在的停靠位点数量。这些结果表明,在中央突触处,水泡停靠位点代表了Katz提出的反应位点。目前,用新的技术组合研究了对接位点的大分子结构和分子组成。
更新日期:2017-08-23
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