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Gap junctions on hippocampal mossy fiber axons demonstrated by thin-section electron microscopy and freeze-fracture replica immunogold labeling

Lookup NU author(s): Professor Miles Whittington



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 (≈30-70 nm in diameter) were found between pairs of mossy fiber axons (≈100-200 nm in diameter) in the stratum lucidum of the CA3b field of the rat ventral hippocampus, and one axonal gap junction (≈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. © 2007 by The National Academy of Sciences of the USA.

Publication metadata

Author(s): Hamzei-Sichani F, Kamasawa N, Janssen WGM, Yasumura T, Davidson KGV, Hof PR, Wearne SL, Stewart MG, Young SR, Whittington MA, Rash JE, Traub RD

Publication type: Article

Publication status: Published

Journal: Proceedings of the National Academy of Sciences of the United States of America

Year: 2007

Volume: 104

Issue: 30

Pages: 12548-12553

Print publication date: 24/07/2007

ISSN (print): 0027-8424

ISSN (electronic): 1091-6490

Publisher: National Academy of Sciences


DOI: 10.1073/pnas.0705281104

PubMed id: 17640909


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Funder referenceFunder name
5R01NS044133-04NINDS NIH HHS
5R01NS046058-04NINDS NIH HHS