PDF(Pubmed)
Abstract：
Experience regulates synapse formation and function across sensory circuits. How inhibitory synapses in the mammalian retina are sculpted by visual cues remains unclear. By use of a sensory deprivation paradigm, we find that visual cues regulate maturation of two GABA synapse types (GABAA and GABAC receptor synapses), localized across the axon terminals of rod bipolar cells (RBCs)-second-order retinal neurons integral to the night-vision circuit. Lack of visual cues causes GABAA synapses at RBC terminals to retain an immature receptor configuration with slower response profiles and prevents receptor recruitment at GABAC synapses. Additionally, the organizing protein for both these GABA synapses, LRRTM4, is not clustered at dark-reared RBC synapses. Ultrastructurally, the total number of ribbon-output/inhibitory-input synapses across RBC terminals remains unaltered by sensory deprivation, although ribbon synapse output sites are misarranged when the circuit develops without visual cues. Intrinsic electrophysiological properties of RBCs and expression of chloride transporters across RBC terminals are additionally altered by sensory deprivation. Introduction to normal 12-h light-dark housing conditions facilitates maturation of dark-reared RBC GABA synapses and restoration of intrinsic RBC properties, unveiling a new element of light-dependent retinal cellular and synaptic plasticity.
摘要：
经验调节感觉回路中的突触形成和功能。哺乳动物视网膜中的抑制性突触是如何通过视觉线索来雕刻的，目前尚不清楚。通过使用感官剥夺范式，我们发现视觉线索调节两种GABA突触类型（GABAA和GABAC受体突触）的成熟，定位在视杆双极细胞（RBC）的轴突末端-二级视网膜神经元，与夜视电路有关。缺乏视觉线索会导致RBC末端的GABAA突触保持反应较慢的未成熟受体构型，并阻止GABAC突触的受体募集。此外,这两个GABA突触的组织蛋白，LRRTM4不聚集在暗饲养的RBC突触处。超微结构，RBC末端的带状输出/抑制性输入突触的总数保持不变，尽管当电路在没有视觉线索的情况下发展时，带状突触输出位点排列错误。感觉剥夺还改变了RBC的固有电生理特性和整个RBC末端的氯化物转运蛋白的表达。介绍正常的12小时明暗住房条件有助于深色饲养的RBCGABA突触的成熟和内在RBC特性的恢复。揭示了光依赖性视网膜细胞和突触可塑性的新元素。
