Neuroscience 2002 Abstract
| Presentation Number: | 129.12 |
|---|---|
| Abstract Title: | Developmental Switch of Axon Guidance Cues for Hippocampal Mossy Fibers. |
| Authors: |
Koyama, R.*1
; Yamada, M. K.1
; Nishiyama, N.1
; Matsuki, N.1
; Ikegaya, Y.1
1Chem Pharmacol, Univ Tokyo Grad Sch Pharm Sci, Tokyo, Japan |
| Primary Theme and Topics |
Development - Axonal and Dendritic Development -- Axon growth and guidance: other |
| Secondary Theme and Topics | Development<br />- Axonal and Dendritic Development<br />-- Axon growth and guidance: extracellular signals |
| Session: |
129. Axonal and dendritic development: axonal growth and guidance I Poster |
| Presentation Time: | Sunday, November 3, 2002 4:00 PM-5:00 PM |
| Location: | Hall A2-B3 B-15 |
| Keywords: | hippocampus, slice culture, chemoattractant, fasciculation |
The hippocampal mossy fibers (MFs) travel within the stratum lucidum close to CA3 stratum pyramidale and form giant synapses with target neurons therein. Because of the difficulty to visualize the MFs, little is known about the mechanisms that guide the MFs to this restricted area. In the present study, we have attempted to solve this problem with an explant coculture system, using transgenic rats expressing green fluorescence protein (GFP(+) rats). When collagen gels were interposed between dentate gyrus (DG) slices prepared from postnatal day 6 (P6) GFP(+) rats and Ammon′s horn slices of wild-type littermates, GFP(+) MFs passed through the gels and reached CA3 stratum lucidum after 10 days in culture, which indicates that the MFs are guided by chemoattractants. However, surprisingly, the MFs could project normally to the host stratum lucidum even when Ammon′s slices were fixed with paraformaldehyde. These results imply that both diffusible and non-diffusible cues are involved in MF pathfinding. To investigate how these different cues participate in MF guidance, a P6 DG slice was cocultured with two Ammon′s horn slices prepared from rats at different ages (P0 and P6). The MFs normally projected to the CA3 stratum lucidum of both the Ammon′s horns. When these two host slices were fixed, however, the MFs made an intrusion only into P6 Ammon′s horn, but not into P0 Ammon′s horn. Thus, the MFs are likely to grow according to diffusible guidance cues at early stages of development, but thereafter, can find their trajectories by a non-diffusible factor, probably fasciculation with preexisting MFs.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2002 Neuroscience Meeting Planner. Orlando, FL: Society for Neuroscience, 2002. Online.
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