Hamzei-Sichani Farid, Kamasawa Naomi, Janssen William G M, Yasumura Thomas, Davidson Kimberly G V, Hof Patrick R, Wearne Susan L, Stewart Mark G, Young Steven R, Whittington Miles A, Rash John E, Traub Roger D
Program in Neural and Behavioral Science, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, USA.
Proc Natl Acad Sci U S A. 2007 Jul 24;104(30):12548-53. doi: 10.1073/pnas.0705281104. Epub 2007 Jul 18.
Gap junctions have been postulated to exist between the axons of excitatory cortical neurons based on electrophysiological, modeling, and dye-coupling data. Here, we provide ultrastructural evidence for axoaxonic gap junctions in dentate granule cells. Using combined confocal laser scanning microscopy, thin-section transmission electron microscopy, and grid-mapped freeze-fracture replica immunogold labeling, 10 close appositions revealing axoaxonic gap junctions ( approximately 30-70 nm in diameter) were found between pairs of mossy fiber axons ( approximately 100-200 nm in diameter) in the stratum lucidum of the CA3b field of the rat ventral hippocampus, and one axonal gap junction ( approximately 100 connexons) was found on a mossy fiber axon in the CA3c field of the rat dorsal hippocampus. Immunogold labeling with two sizes of gold beads revealed that connexin36 was present in that axonal gap junction. These ultrastructural data support computer modeling and in vitro electrophysiological data suggesting that axoaxonic gap junctions play an important role in the generation of very fast (>70 Hz) network oscillations and in the hypersynchronous electrical activity of epilepsy.
基于电生理、建模和染料偶联数据，推测兴奋性皮层神经元的轴突之间存在缝隙连接。在此，我们提供了齿状颗粒细胞中轴-轴突缝隙连接的超微结构证据。使用共聚焦激光扫描显微镜、超薄切片透射电子显微镜和网格映射冷冻断裂复制品免疫金标记相结合的方法，在大鼠腹侧海马CA3b区透明层中，发现10对紧密相邻的苔藓纤维轴突（直径约100-200nm）之间存在轴-轴突缝隙连接（直径约30-70nm），在大鼠背侧海马CA3c区的一条苔藓纤维轴突上发现一个轴突缝隙连接（约100个连接子）。用两种大小的金珠进行免疫金标记显示，连接蛋白36存在于该轴突缝隙连接中。这些超微结构数据支持计算机建模和体外电生理数据，表明轴-轴突缝隙连接在产生非常快速（>70Hz）的网络振荡和癫痫的超同步电活动中起重要作用。
