Properties of short-term synaptic depression at larval neuromuscular synapses in wild-type and temperature-sensitive paralytic mutants of Drosophila
Properties of short-term synaptic depression at larval neuromuscular synapses in wild-type and temperature-sensitive paralytic mutants of Drosophila
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DOI：
10.1152/jn.01108.2004
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发表时间：
2005-05-01
影响因子：
2.5
通讯作者：
Ordway, RW
中科院分区：
文献类型：
--
作者：
Wu, Y;Kawasaki, F;Ordway, RW
果蝇幼虫神经肌肉突触是研究突触发育和功能的重要模型。进一步的功能特性，这种突触，以及成人神经肌肉突触，将大大提高我们的理解突触传递的影响，这个模型系统。在这里，我们描述了一种形式的短期突触抑制观察幼虫，但不是成人，神经肌肉突触，并探讨潜在的机制。幼虫的神经肌肉突触表现出一种短期抑郁的形式，强烈依赖于刺激频率在一个狭窄的范围内的低频率（0.1-1赫兹）。这种形式的突触抑制，这里称为低频短期抑制（LF-STD），是由神经递质释放的活动依赖性减少引起的。然而，在相反的耗尽模型的预测，抑郁症的程度是独立的神经递质释放的初始水平在一个范围内的细胞外钙浓度。这一结论得到证实，在两个温度敏感（TS）麻痹突变体，杂音和shibire，表现出减少神经递质释放导致突触前钙通道和发动蛋白的条件性破坏，分别。更高的刺激频率（40或60 Hz）产生了两种抑郁成分，似乎包括LF-STD以及短期抑郁的更常规成分。这些发现揭示了短期突触抑制的新特性，并表明幼虫和成人神经肌肉突触的互补遗传分析将进一步确定神经递质释放和短期突触可塑性的体内机制。
The larval neuromuscular synapse of Drosophila serves as an important model for genetic and molecular analysis of synaptic development and function. Further functional characterization of this synapse, as well as adult neuromuscular synapses, will greatly enhance the impact of this model system on our understanding of synaptic transmission. Here we describe a form of short-term synaptic depression observed at larval, but not adult, neuromuscular synapses and explore the underlying mechanisms. Larval neuromuscular synapses exhibited a form of short-term depression that was strongly dependent on stimulation frequency over a narrow range of low frequencies (0.1-1 Hz). This form of synaptic depression, referred to here as low-frequency short-term depression (LF-STD), results from an activity-dependent reduction in neurotransmitter release. However, in contrast to the predictions of depletion models, the degree of depression was independent of the initial level of neurotransmitter release over a range of extracellular calcium concentrations. This conclusion was confirmed in two temperature-sensitive (TS) paralytic mutants, cacophony and shibire, which exhibit reduced neurotransmitter release resulting from conditional disruption of presynaptic calcium channels and dynamin, respectively. Higher stimulation frequencies (40 or 60 Hz) produced two components of depression that appeared to include LF-STD as well as a more conventional component of short-term depression. These findings reveal novel properties of short-term synaptic depression and suggest that complementary genetic analysis of larval and adult neuromuscular synapses will further define the in vivo mechanisms of neurotransmitter release and short-term synaptic plasticity.