Chemical Senses Advance Access originally published online on March 1, 2006
Chemical Senses 2006 31(4):371-378; doi:10.1093/chemse/bjj041
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Modification of Synapse Formation of Accessory Olfactory Bulb Neurons by Coculture with Vomeronasal Neurons
1 Laboratory of Anatomy and Cell Biology, Department of Neuroscience Basic Technology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan, 2 Department of Biomolecular Science, Faculty of Science, Toho University, Funabashi, Chiba 274-8510, Japan, 3 Department of Biology, Faculty of Science, Ochanomizu University, Bunkyo-ku, Tokyo 112-8610, Japan and 4 Department of Integrative Physiology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan
Correspondence to be sent to: Masumi Ichikawa, Laboratory of Anatomy and Cell Biology, Department of Neuroscience Basic Technology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526, Japan. e-mail: mich{at}tmin.ac.jp
Previously, a coculture system of accessory olfactory bulb (AOB) neurons and vomeronasal (VN) neurons was established for studying the functional roles of AOB neurons in pheromonal signal processing. In this study, the effect of VN neurons on the development of AOB neurons was examined in a coculture system. Spine density was quantitatively measured for various culture periods of 21, 28, 36, and 42 days in vitro. The densities of dendritic spines were lower in the coculture than in single culture for all periods in vitro. Synapse formation on spines was analyzed immunocytochemically using an anti-synaptophysin antibody. The ratio of the density of synaptophysin-immunopositive spine/total spine density was larger in the coculture than in the single culture. The volume of spine head was larger in the coculture than in single culture. These changes were not observed in the coculture in which there was no physical contact between AOB neurons and VN neurons. These observations suggest that synapse formation on the spines of AOB neurons is modified by physical contact with VN neurons.
Key words: accessory olfactory bulb, confocal laser microscope, EGFPactin, spine, vomeronasal organ