Abstract
Despite the importance of neuropeptide release, which is evoked by long bouts of action potential activity and which regulates behavior, peptidergic vesicle movement has not been examined in living nerve terminals. Previous in vitro studies have found that secretory vesicle motion at many sites of release is constitutive: Ca(2+) does not affect the movement of small synaptic vesicles in nerve terminals or the movement of large dense core vesicles in growth cones and endocrine cells. However, in vivo imaging of a neuropeptide, atrial natriuretic factor, tagged with green fluorescent protein in larval Drosophila melanogaster neuromuscular junctions shows that peptidergic vesicle behavior in nerve terminals is sensitive to activity-induced Ca(2+) influx. Specifically, peptidergic vesicles are immobile in resting synaptic boutons but become mobile after seconds of stimulation. Vesicle movement is undirected, occurs without the use of axonal transport motors or F-actin, and aids in the depletion of undocked neuropeptide vesicles. Peptidergic vesicle mobilization and post-tetanic potentiation of neuropeptide release are sustained for minutes.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Animals, Genetically Modified
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Atrial Natriuretic Factor / genetics
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Atrial Natriuretic Factor / metabolism*
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Cadmium / pharmacology
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Calcium / metabolism
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Cytochalasin D / pharmacology
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Diagnostic Imaging / methods
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Dose-Response Relationship, Radiation
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Drosophila
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Electric Stimulation / methods
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Enzyme Inhibitors / pharmacology
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Ethylmaleimide / pharmacology
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Green Fluorescent Proteins / genetics
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Green Fluorescent Proteins / metabolism
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In Vitro Techniques
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Microscopy, Confocal / methods
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Neuromuscular Junction / drug effects
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Neuromuscular Junction / physiology*
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Neuromuscular Junction / radiation effects
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Nucleic Acid Synthesis Inhibitors / pharmacology
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Photobleaching
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Presynaptic Terminals / drug effects
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Presynaptic Terminals / metabolism
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Presynaptic Terminals / radiation effects
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Secretory Vesicles / drug effects
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Secretory Vesicles / metabolism*
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Secretory Vesicles / radiation effects
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Synaptic Vesicles / drug effects
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Synaptic Vesicles / metabolism*
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Synaptic Vesicles / radiation effects
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Time Factors
Substances
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Enzyme Inhibitors
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Nucleic Acid Synthesis Inhibitors
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Cadmium
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Green Fluorescent Proteins
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Cytochalasin D
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Atrial Natriuretic Factor
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Ethylmaleimide
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Calcium