Source of Calcium Transients Involved in Synaptic Scaling in the Chick Embryo Open Access
Lampert, Maddie (Spring 2025)
Abstract
Background: Homeostatic plasticity describes the set of mechanisms that act to ensure neurons maintain appropriate levels of excitability amidst chronic perturbations. Deficits in homeostatic plasticity have been proposed to be implicated in a range of nervous system disorders including autism spectrum disorders. It has been previously established that rapid homeostatic synaptic scaling in the chick embryo is mediated by NMDA receptor activation associated with miniature postsynaptic currents (mPSCs), but the downstream substrate that triggers a change in postsynaptic current amplitude remains unknown. Recent evidence suggests calcium as the key substrate, but this theory has not yet been investigated in the chick embryo, and the source of calcium has not been identified.
Methods: Motor neurons from the embryonic chick spinal cord were labeled with cytoplasmic and mitochondrial calcium indicators and imaged in TTX before, during, and after treatment with AMPA, NMDA, and GABA receptor antagonists to quantify the frequency of mini-induced calcium transients.
Results: Data from a total of 6 cords filled with Calcium Green Dextran and 3 cords electroporated with mito-GCaMP6F were collected and included in the analysis. The frequency of cytoplasmic, but not mitochondrial, calcium transients decreased in the presence of the antagonists.
Conclusion: This is the first study to investigate calcium transients induced by miniature post-synaptic currents in embryonic chick spinal motorneurons. The significant reduction of cytoplasmic calcium fluorescence upon inhibition of mPSCs provides further evidence that one, all, or a combination of these receptors serve as essential sources of calcium in this system. Future studies should build upon these findings to identify the specific source of calcium and its downstream effects that induce scaling.
Table of Contents
Introduction & Background ……………………………………………………………………......…1
Figure 1 - Effect of Ru265 on mitochondrial calcium fluorescence………………..…..…5
Research Question and Hypothesis………………………………………………………..….......……6
Methods…………………………………………………………………………………….…...................7
Figure 2 – Embryonic development and tissue preparation timeline………………..…..…8
Figure 3 – Chick embryo spinal cord………………………………………………..............……9
Figure 4 – Calcium imaging snapshots…………….…………….…………….…...........……..11
Results …………………………………………………………………….…………...……...............…..12
Figure 5 – Cytoplasmic and mitochondrial calcium in spinal motor neuron dendrites…13
Figure 6 – Distribution of raw fluorescence values…………………………………...............13
Figure 7 – Representative ROI trace of cytoplasmic calcium fluorescence………....……..14
Figure 8 – Frequency of cytoplasmic calcium transients……………………….……........….15
Figure 9 – Representative ROI trace of mitochondrial calcium fluorescence……….........16
Figure 10 – Frequency of mitochondrial calcium transients………………...……...…........17
Discussion………………………………………………………………………………...............….........18
Conclusion……………………………………………………………………………................….………21
References……………………….………………………………………………………….…................…22
About this Honors Thesis
| School | |
|---|---|
| Department | |
| Degree | |
| Submission | |
| Language |
|
| Research Field | |
| Keyword | |
| Committee Chair / Thesis Advisor | |
| Committee Members |
Primary PDF
| Thumbnail | Title | Date Uploaded | Actions |
|---|---|---|---|
|
|
Source of Calcium Transients Involved in Synaptic Scaling in the Chick Embryo () | 2025-04-09 11:34:57 -0400 |
|
Supplemental Files
| Thumbnail | Title | Date Uploaded | Actions |
|---|