Neuroscience 2004 Abstract
| Presentation Number: | 614.17 |
|---|---|
| Abstract Title: | Time-lapse imaging of EGFP tagged AMPA receptors during synaptic activity blockade. |
| Authors: |
Ibata, K.*1
; Turrigiano, G. G.1
1Brandeis Univ, Waltham, MA |
| Primary Theme and Topics |
Development - Synaptogenesis and Activity-Dependent Development -- Activity-dependent development and plasticity |
| Session: |
614. Activity-Dependent Development and Plasticity VII Poster |
| Presentation Time: | Tuesday, October 26, 2004 8:00 AM-9:00 AM |
| Location: | San Diego Convention Center - Hall A-H, Board # F1 |
| Keywords: | SYNAPTIC PLASTICITY, POSTSYNAPTIC, GLUTAMATE RECEPTOR, TTX |
Cortical neurons can adjust synaptic strength to compensate for changes in external drive, both in vitro and in vivo. We reported that activity blockade increased the accumulation of native AMPA receptors detected with immunolabeling, accounting for the increase in quantal amplitude induced by activity blockade (2003 SFN abstract). To date, studies of synaptic scaling have not been able to follow changes in individual neurons or postsynaptic sites. To investigate the role of receptor accumulation in individual neurons and postsynaptic sites, we performed time-lapse imaging of neurons that expressed EGFP-GluR2. The transfected cell showed distinct puncta and diffuse dendritic fluorescence. These puncta were well colocalized with surface anti-EGFP staining and anti-GluR2 staining, indicating EGFP-GluR2 was correctly trafficked to postsynaptic site. Furthermore, EGFP-GluR2 fluorescence and the amount of surface EGFP were well correlated. To select synaptically localized EGFP-GluR2 more efficiently, we co-transfected with PSD95-DsRed. Individual neurons were imaged at either 1 day or 2 hour time intervals. Synaptic EGFP-GluR2 accumulation was expressed as a ratio of synaptic peak intensity / dendrite intensity. At 1 day time intervals in control cells, peak / dendrite ratio did not change (p > 0.4, n = 8). In TTX-treated cells, however, peak / dendrite ratio increased significantly (184 ± 8 %, p < 0.001, paired t-test, n = 10). At 2 hour time intervals, we were able to follow individual puncta throughout the experiment. In control condition, average of peak / dendrite ratio for puncta that persisted over 12 hours did not change. On the other hand, peak / dendrite ratio from TTX-treated cells increased gradually over time, and after 12 hours, it was 138 ± 8 % of initial ratio (p < 0.001, n = 100 puncta from 8 cells). These results are direct evidence that existing individual postsynaptic sites on the dendrites of a neuron can increase their AMPA receptor accumulation to compensate for lowered external activity.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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