The synaptic architecture of AMPA receptors at the cone pedicle of the primate retina
The synaptic architecture of AMPA receptors at the cone pedicle of the primate retina
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DOI：
10.1523/jneurosci.21-07-02488.2001
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发表时间：
2001-04-01
影响因子：
5.3
通讯作者：
Wässle, H
中科院分区：
文献类型：
--
作者：
Haverkamp, S;Grünert, U;Wässle, H
视锥蒂是视锥光感受器的输出突触，将光信号传递到双极细胞和水平细胞的树突上。视锥椎弓根包含20至45个带状突触（三联体），这些突触是视锥递质谷氨酸的释放部位。数百个突触后树突接触单个视锥梗，我们研究了在这些接触处表达和聚集的谷氨酸受体，特别是AMPA受体亚基。使用免疫细胞化学和共聚焦成像，我们能够通过光学显微镜解析视锥梗内的单个三联体。我们研究了它们在L/M-和S-视锥中的差异，并计算了视网膜上每个蒂的三元组数量。用突触前基质蛋白巴松管、突触相关膜蛋白P84和花生凝集素分别特异性标记突触带、水平细胞内陷树突和ON-锥双极细胞内陷树突，用包埋前后免疫细胞化学和电镜技术对AMPA受体亚基在锥体蒂基部进行定位。它们聚集在三个不同的突触后位点：在水平的细胞内陷接触，在双极细胞平面接触，并在桥粒样连接锥pedicles.We下面的三个特定的标记物和抗体的AMPA受体亚基进行双标记实验。AMPA受体优先表达水平的细胞，并在较小程度上关闭锥双极细胞。我们没有观察到任何锥选择性表达的AMPA受体亚基突触后的L/M-或S-锥，表明AMPA受体不是理解灵长类动物视网膜三色信号的关键。
Cone pedicles, the output synapses of cone photoreceptors, transfer the light signal onto the dendrites of bipolar and horizontal cells. Cone pedicles contain between 20 and 45 ribbon synapses (triads) which are the release sites for glutamate, the cone transmitter. Several hundred postsynaptic dendrites contact individual cone pedicles, and we studied the glutamate receptors expressed and clustered at these contacts, particularly the AMPA receptor subunits.Using immunocytochemistry and confocal imaging we were able to resolve individual triads within the cone pedicles by light microscopy. We studied their differences in L/M- and S-cones, and we counted the number of triads per pedicle across the retina. The presynaptic matrix protein bassoon, the synapse-associated membrane protein P84, and peanut agglutinin were used to specifically label synaptic ribbons, invaginating dendrites of horizontal cells and invaginating dendrites of ON-cone bipolar cells, respectively.Pre- and post-embedding immunocytochemistry and electron microscopy were used to localize the AMPA receptor subunits at the cone pedicle base. They were aggregated at three different postsynaptic sites: at horizontal cell invaginating contacts, at bipolar cell flat contacts, and at desmosome-like junctions underneath the cone pedicles.We also performed double-labeling experiments with the triad-specific markers and the antibodies against the AMPA receptor subunits. AMPA receptors were preferentially expressed by horizontal cells, and to a lesser extent by OFF-cone bipolar cells. We did not observe any cone-selective expression of AMPA receptor subunits postsynaptic to L/M- or S-cones, suggesting AMPA receptors are not the key to understanding trichromatic signaling in the primate retina.