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Dopamine Release at Individual Presynaptic Terminals Visualized with FFNs
Published on: August 31, 2009
Stimulus-dependent alterations in quantal neurotransmitter release.
1Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06511, USA. cpg22@email.med.yale.edu
Journal of Neurophysiology
|September 8, 2006
Summary
Calcium ion concentration ([Ca(2+)]) dynamics critically influence neurotransmitter release. Different stimulation methods reveal distinct vesicle fusion and release patterns, highlighting localized calcium signaling
Area of Science:
- Neurobiology
- Cellular Physiology
- Biochemistry
Background:
- Neurotransmitter release is tightly regulated by intracellular calcium ion concentration ([Ca(2+)]) at release sites.
- Both the amplitude and temporal dynamics of [Ca(2+)] influence vesicle exocytosis and neurotransmitter content release.
Purpose of the Study:
- To investigate how different patterns of [Ca(2+)] presentation affect catecholamine release from mouse chromaffin cells.
- To compare neurotransmitter release characteristics elicited by global calcium elevation versus localized calcium influx.
Main Methods:
- Stimulation of mouse chromaffin cells using digitonin permeabilization for global [Ca(2+)] elevation.
- Stimulation using nicotine to induce voltage-dependent calcium channel activation and localized [Ca(2+)] changes.
- Amperometry was employed to monitor catecholamine release and characterize vesicle fusion events.
Main Results:
- Both stimulation methods resulted in similar total neurotransmitter release per large dense-core vesicle (LDCV).
- Digitonin-induced release was characterized by large, fast events, while nicotine-induced release showed small, slow events.
- The fusion pore 'foot' was largely absent in digitonin-stimulated cells but common in nicotine-stimulated cells.
Conclusions:
- Distinct patterns of [Ca(2+)] at release sites significantly alter individual vesicle fusion and release kinetics.
- Localized and phasic calcium signals promote transient fusion pore openings, whereas global calcium elevation favors rapid, complete vesicle fusion.
- These findings underscore the importance of spatial and temporal calcium dynamics in regulating neurotransmitter release specificity.
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