Tetanic stimulation recruits vesicles from reserve pool via a cAMP-mediated process in Drosophila synapses.
At Drosophila neuromuscular junctions, there are two synaptic vesicle pools, namely the exo/endo cycling pool (ECP) and the reserve pool (RP). We studied the recruitment process from RP using a fluorescent dye, FMI-43. During high-frequency nerve stimulation, vesicles in RP were recruited for release, and endocytosed vesicles were incorporated into both pools, whereas with low-frequency stimulation, vesicles were incorporated into and released from ECP. Release of vesicles from RP was detected electrophysiologically after emptying vesicles in the ECP of transmitter by a H+ pump inhibitor. Recruitment from RP was depressed by inhibitors of steps in the cAMP/PKA cascade and enhanced by their activators. In rutabaga (rut) with low cAMP levels, mobilization of vesicles from RP during tetanic stimulation was depressed, while it was enhanced in dunce (dnc) with high cAMP levels.
Institute for Behavioral Sciences, Gunma University School of Medicine, Maebashi, Japan. kuromi@med.gunma-u.ac.jp
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Kuromi
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Kidokoro
D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004330:Drosophila / Q000502:physiology*; D004558:Electric Stimulation; D004594:Electrophysiology; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes; D018942:Macrolides; D008568:Memory / Q000502:physiology; D017729:Presynaptic Terminals / Q000502:physiology; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D011999:Recruitment, Neurophysiological / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology; D013572:Synaptic Vesicles / Q000502:physiology*
D000067956:Adenylyl Cyclase Inhibitors; D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D020536:Enzyme Activators; D004791:Enzyme Inhibitors; C073804:FM1 43; D005456:Fluorescent Dyes; D018942:Macrolides; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; C040929:bafilomycin A1; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases