突触囊泡循环研究进展

Research progress of synaptic vesicle recycling

神经信号传递始于神经递质从突触囊泡的释放。在此过程中,突触囊泡需要经历释放-回收的动态过程以维持突触前终末的结构和功能的完整性。突触的传递始于一个动作电位沿轴突传递到终扣(bouton)使其去极化,突触前轴突末梢内的钙离子浓度升高并触发突触囊泡膜与突触前膜融合而导致递质释放,然后囊泡膜被回收利用。这些看似简单的"释放—回收—再释放"的过程其实包含了很多极其精细的调控步骤、中间过程和动态变化;越来越多的证据表明在不同刺激条件下囊泡释放的能力和运动方式有很大的差别。分子和细胞水平的研究一直致力于研究突触囊泡的这些多样性,希望找出囊泡的结构与其功能的确切关系,了解对囊泡的调控如何影响突触传导和可塑性。不同类型突触表现出不同的突触前囊泡活动性质也逐渐为人们所认识。科学家们对突触前囊泡循环过程的深入研究过程与研究技术手段的进步相辅相成,推动了这个领域的发展。本文将主要从三个方面对突触前囊泡循环的研究进展进行总结和讨论:(1)突触前囊泡池(vesicle pools)与囊泡循环(vesicle recycling);(2)谷氨酸能和GABA能突触前囊泡循环分子机制差异研究进展;(3)突触前囊泡循环机制研究的方法比较和最新发展。

Neurotransmission begins with neurotransmitter being released from synaptic vesicles. To achieve this function, synaptic vesicles endure the dynamic ＂release-recycle＂ process to maintain the function and structure of presynaptic terminal. Synaptic transmission starts with a single action potential that depolarizes axonal bouton, followed by an increase in the cytosolic calcium concentration that triggers the synaptic vesicle membrane fusion with presynaptic membrane to release neurotransmitter; then the vesicle membrane can be endocytosed for reusing afterwards. This process requires delicate regulation, intermediate steps and dynamic balances. Accumulating evidence showed that the release ability and mobility of synapses varies under different stimulations. Synaptic vesicle heterogeneity has been studied at molecular and cellular levels, hopefully leading to the identification of the relationships between structure and function and understanding how vesicle regulation affects synaptic transmission and plasticity. People are beginning to realize that different types of synapses show diverse presynaptic activities. The steady advances of technology studying synaptic vesicle recycling promote people＇s understanding of this field. In this review, we discuss the following three aspects of the research progresses on synaptic vesicle recycling： 1） presynaptic vesicle pools and recycling; 2） research progresses on the differences of glutamatergic and GABAergic presynaptic vesicle recycling mechanism and 3） comparison of the technologies used in studying presyanptic vesicle recycling and the latest progress in the technology development in this field.