Brandstätter J H, Löhrke S, Morgans C W, Wässle H
Abteilung für Neuroanatomie, Max-Planck-Institut für Hirnforschung, Frankfurt a. Main, Germany.
J Comp Neurol. 1996 Jun 17;370(1):1-10. doi: 10.1002/(SICI)1096-9861(19960617)370:1<1::AID-CNE1>3.0.CO;2-7.
Synaptophysin and synaptoporin are homologous proteins that are among the most abundant synaptic vesicle proteins. Despite their high degree of sequence similarity, they are differentially distributed in the brain. The distribution of synaptophysin and synaptoporin was examined in the adult rat and rabbit retina by using single- and double- labeling immunocytochemistry with conventional light microscopy and confocal laser scanning microscopy. In the rat retina, synaptophysin immunoreactivity was found in the outer plexiform layer in terminals of photoreceptors and was homogeneously distributed throughout the inner plexiform layer. Synaptoporin immunoreactivity, however, was restricted to the inner plexiform layer. Labeling was most prominent in three distinct bands of the inner plexiform layer separated by two bands of very low synaptoporin immunoreactivity. In the rabbit retina, synaptophysin and synaptoporin immunoreactivity were found in the inner and outer plexiform layers. In the inner plexiform layer, labeling for both vesicle proteins was homogeneous, with no detectable stratification. In the outer plexiform layer, synaptophysin was present in photoreceptor terminals, and synaptoporin was present in horizontal cells. Staining of isolated rabbit retinal cells confirmed that both the axonless A type and the axon-bearing B type horizontal cells are immunoreactive for synaptoporin. In addition, electron microscopy of synaptoporin-immunostained rabbit retinas revealed no labeling of photoreceptor terminals but of putative synaptic sites in horizontal cells in the outer plexiform layer. No functional correlation was found in the expression of either synaptic vesicle protein with the type of neuron or synapse (ribbon or conventional).
突触素和突触孔蛋白是同源蛋白，是最丰富的突触小泡蛋白之一。尽管它们的序列相似度很高，但在大脑中的分布却有所不同。通过使用传统光学显微镜和共聚焦激光扫描显微镜的单标记和双标记免疫细胞化学方法，研究了成年大鼠和兔视网膜中突触素和突触孔蛋白的分布。在大鼠视网膜中，突触素免疫反应性见于光感受器终末所在的外网状层，并均匀分布于整个内网状层。然而，突触孔蛋白免疫反应性仅限于内网状层。标记在内网状层三个不同的带中最为明显，这三个带被两个突触孔蛋白免疫反应性极低的带分隔开。在兔视网膜中，突触素和突触孔蛋白免疫反应性见于内、外网状层。在内网状层，两种小泡蛋白的标记是均匀的，没有可检测到的分层。在外网状层，突触素存在于光感受器终末，突触孔蛋白存在于水平细胞中。对分离的兔视网膜细胞的染色证实，无轴突的A型和有轴突的B型水平细胞对突触孔蛋白均有免疫反应性。此外，对突触孔蛋白免疫染色的兔视网膜进行电子显微镜检查发现，光感受器终末没有标记，但在外网状层水平细胞的假定突触部位有标记。在任何一种突触小泡蛋白的表达与神经元类型或突触类型（带状或传统型）之间均未发现功能相关性。
