Neuroscience 2001 Abstract
| Presentation Number: | 797.15 |
|---|---|
| Abstract Title: | Spontaneous calcium oscillations are associated with slowing of cortical axon outgrowth. |
| Authors: |
Tang, F.*1
; Kalil, K.1,2
1Neuroscience Training Program, University of Wisconsin, Madison, WI 2Department of Anatomy, University of Wisconsin, Madison, WI |
| Primary Theme and Topics |
Development - Axonal and Dendritic Development -- Axon guidance: receptors and signaling mechanisms |
| Secondary Theme and Topics | Development<br />- Axonal and Dendritic Development<br />-- Axon outgrowth: receptors and signaling mechanisms |
| Session: |
797. Axonal and dendritic development: axon guidance--CNS II Poster |
| Presentation Time: | Wednesday, November 14, 2001 3:00 PM-4:00 PM |
| Location: | Exhibit Hall B-62 |
| Keywords: | CORTICAL DEVELOPMENT, GROWTH CONE, AXON BRANCHING, FLUORESCENCE IMAGING |
Developing neurons exhibit spontaneous fluctuations in intracellular calcium which regulate several aspects of their differentiation, including axon outgrowth. In previous studies we found that branching of cortical axons was preceded by pausing and enlargement of the primary growth cone. To test whether calcium transients play a role in slowing the advance of cortical growth cones, we measured intracellular calcium dynamics in postnatal cortical growth cones using the sensitive calcium indicator Fluo-4. Time lapse fluorescence imaging for periods up to 1 hour revealed that cortical neurons exhibit calcium oscillations, that apparently occur simultaneously throughout the neuron. These oscillations appeared in bursts at frequencies that varied from 10 per hour up to several per minute. We measured amplitude relative to baseline in growth cones of different sizes and growth states. Preliminary analysis suggests that the large paused growth cones exhibit the highest frequency (average 1 per minute) and amplitude (about 100% over baseline) of calcium fluctuations, although some of these growth cones (20%) had stable calcium levels. In contrast, only 20% of the rapidly growing growth cones exhibit calcium oscillations. These were smaller in amplitude (about 10% over baseline) and less frequent. TTX completely blocked all calcium oscillations, suggesting their dependence on electrical activity. These results suggest that oscillations in intracellular calcium levels may play a role in regulating changes in rates of cortical axon outgrowth which could lead to axon branching.
Supported by NIH Grants NS 14428 and NS 34270 to K.K.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2001 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2001. Online.
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