The kinetics of synaptic vesicle pool depletion at CNS synaptic terminals.

TitleThe kinetics of synaptic vesicle pool depletion at CNS synaptic terminals.
Publication TypeJournal Article
Year of Publication2004
AuthorsFernandez-Alfonso T, Ryan TA
Date Published2004 Mar 25
KeywordsAction Potentials, Animals, Animals, Newborn, Cells, Cultured, Central Nervous System, Electric Stimulation, Endocytosis, Exocytosis, Kinetics, Membrane Fusion, Presynaptic Terminals, Pyridinium Compounds, Quaternary Ammonium Compounds, Rats, Rats, Sprague-Dawley, Synaptic Membranes, Synaptic Transmission, Synaptic Vesicles, Temperature

During sustained action potential (AP) firing at nerve terminals, the rates of endocytosis compared to exocytosis determine how quickly the available synaptic vesicle pool is depleted, in turn influencing presynaptic efficacy. Mechanisms, including rapid kiss-and-run endocytosis as well as local, preferential recycling of docked vesicles, have been proposed as a means to allow endocytosis and recycling to keep up with stimulation. We show here that, for CNS nerve terminals at physiological temperatures, endocytosis is sufficiently fast to avoid vesicle pool depletion during continuous AP firing at 10 Hz. This endocytosis-exocytosis balance persists for turnover of the entire releasable pool of vesicles and allows for efficient escape of FM 4-64, indicating that it is a non-kiss-and-run endocytic event. Thus, under physiological conditions, the sustained speed of vesicle membrane retrieval for the entire releasable pool appears to be sufficiently fast to compensate for exocytosis, avoiding significant vesicle pool depletion during robust synaptic activity.

Alternate JournalNeuron
PubMed ID15046726
Grant ListR01 NS036942 / NS / NINDS NIH HHS / United States