Synaptic Vesicle Exocytosis at the Dendritic Lobules of an Inhibitory Interneuron in the Mammalian Retina.
Synaptic Vesicle Exocytosis at the Dendritic Lobules of an Inhibitory Interneuron in the Mammalian Retina.
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DOI：
10.1016/j.neuron.2015.07.016
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发表时间：
2015-08-05
期刊：
影响因子：
16.2
通讯作者：
von Gersdorff H
中科院分区：
文献类型：
--
作者：
Balakrishnan V;Puthussery T;Kim MH;Taylor WR;von Gersdorff H
带状突触在视网膜微电路内传递持续和阶段性的兴奋驱动。然而，视网膜抑制性突触的特性却鲜为人知。所有无长突细胞是视网膜中的中间神经元，在其树突小叶附属物上表现出大的甘氨酸能突触。使用膜电容测量，我们观察到位于小叶附属物上的 L 型 Ca2+ 通道的开放引起的强大的胞吐作用。检测到两个突触小泡池：一个小的、快速释放的池和一个更大的、更缓慢释放的池。根据刺激的不同，可以引发配对脉冲抑制或促进。在出生后早期成熟期间，胞吐 Ca2+ 传感器与 Ca2+ 通道的耦合变得更紧密。光引起的 AII 无长突细胞的去极化引发了胞吐作用，胞吐作用根据光强度分级。我们的结果表明，AII-无长突细胞突触能够向其突触后伙伴提供阶段性和持续性的抑制输入，而无需突触带的帮助。
Ribbon synapses convey sustained and phasic excitatory drive within retinal microcircuits. However, the properties of retinal inhibitory synapses are less well known. AII-amacrine cells are interneurons in the retina that exhibit large glycinergic synapses at their dendritic lobular appendages. Using membrane capacitance measurements we observe robust exocytosis elicited by the opening of L-type Ca2+ channels located on the lobular appendages. Two pools of synaptic vesicles were detected: a small, rapidly releasable pool and a larger and more slowly releasable pool. Depending on the stimulus, either paired-pulse depression or facilitation could be elicited. During early postnatal maturation, the coupling of the exocytosis Ca2+-sensor to Ca2+ channel becomes tighter. Light-evoked depolarizations of the AII-amacrine cell elicited exocytosis that was graded to light intensity. Our results suggest that AII-amacrine cell synapses are capable of providing both phasic and sustained inhibitory input to their postsynaptic partners without the benefit of synaptic ribbons.