| Abstract No.: | B-B2026 |
| Country: | Canada |
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| Title: | VISUALLY INDUCED LTD REGULATES TRANSCRIPTION AND SYNAPTIC PROPERTIES IN VIVO. |
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| Authors/Affiliations: | 1 Neil Schwartz*; 1 Edward S. Ruthazer;
1 McGill University, Montreal, QC, Canada
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| Content: | Objectives: To determine the effects of visually induced synaptic long-term depression (LTD) on transcription, dendritic morphology and synaptic properties in tectal cells in vivo.
Materials and Methods: To determine if a repeating visual stimulus could induce LTD in vivo, AMPA receptor trafficking was monitored in Xenopus laevis tadpoles by whole cell recordings of AMPA EPSCs, and by in vivo imaging of tectal cells transfected with AMPAr GluR2 subunits tagged with a pH-sensitive gfp (SEP-GluR2) that increases its fluorescence manifold on the surface of the cell. To determine if transcription was induced by the repeating visual stimulus, cells in the whole animal were transfected with a plasmid encoding gfp under the control of an IL-2 promoter.
Results: Exposure of the animals to 15’ of the repeating visual stimulus induced LTD of AMPAr EPSCs which was blocked by either inclusion of the calcineurin inhibitor fk506 in the patch pipette or by bath application of the NMDAr antagonist AP5. Similarly increased trafficking of the SEP-GluR2 was observed following stimulation. Furthermore in cells expressing gfp under the control of the IL-2 promoter, the increase in fluorescence intensity over a four hour period following stimulation was greater than the increase observed over a 4 hr period without stimulation.
Conclusions: Our results indicate that a repeating visual stimulus can induce LTD in vivo and that this results in transcriptional activation and AMPAr trafficking.
This work was supported by grants from the CIHR, the EJLB Foundation and NARSAD.
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