scholarly journals Discharge of the Readily Releasable Pool With Action Potentials at Hippocampal Synapses

2007 ◽  
Vol 98 (6) ◽  
pp. 3221-3229 ◽  
Author(s):  
Charles F. Stevens ◽  
James H. Williams
Keyword(s):  
Cell Culture ◽  
Synaptic Vesicles ◽  
Action Potentials ◽  
Synaptic Function ◽  
Hypertonic Solution ◽  
Synaptic Release ◽  
Releasable Pool ◽  
Readily Releasable Pool ◽  
Hippocampal Synapses ◽  
Asynchronous Release

A readily releasable pool (RRP) of synaptic vesicles has been identified at hippocampal synapses with application of hypertonic solution. RRP size correlates with important properties of synaptic function such as release probability. However, a discrepancy in RRP size has been reported depending on the method used to evoke synaptic release. This study was undertaken to determine quantitative relationships between the RRP defined with hypertonic solution and that released with trains of action potentials. We find that asynchronous release at cell culture synapses contributes significantly to the discharge of the RRP with trains of action potentials and that RRP size is the same when elicited by either nerve stimuli or hypertonic challenge.

Changes in the Readily Releasable Pool of Transmitter and in Efficacy of Release Induced by High-Frequency Firing at Aplysia Sensorimotor Synapses in Culture

2004 ◽  
Vol 91 (4) ◽  
pp. 1500-1509 ◽  
Author(s):  
Yali Zhao ◽  
Marc Klein
Keyword(s):  
Motor Neuron ◽  
High Frequency ◽  
Transmitter Release ◽  
Action Potentials ◽  
High Frequency Stimulation ◽  
Hypertonic Solution ◽  
Posttetanic Potentiation ◽  
Releasable Pool ◽  
Readily Releasable Pool ◽  
Frequency Stimulation

Synaptic transmission at the sensory neuron-motor neuron synapses of Aplysia, like transmission at many synapses of both vertebrates and invertebrates, is increased after a short burst of high-frequency stimulation (HFS), a phenomenon known as posttetanic potentiation (PTP). PTP is generally attributable to an increase in transmitter release from presynaptic neurons. We investigated whether changes in the readily releasable pool of transmitter (RRP) contribute to the potentiation that follows HFS. We compared the changes in excitatory postsynaptic potentials (EPSPs) evoked with action potentials to changes in the RRP as estimated from the asynchronous transmitter release elicited by a hypertonic solution. The changes in the EPSP were correlated with changes in the RRP, but the changes matched quantitatively only at connections whose initial synaptic strength was greater than the median for all experiments. At weaker connections, the increase in the RRP was insufficient to account for PTP. Weaker connections initially released a smaller fraction of the RRP with each EPSP than stronger ones, and this fraction increased at weaker connections after HFS. Moreover, the initial transmitter release in response to the hypertonic solution was accelerated after HFS, indicating that the increase in the efficacy of release was not restricted to excitation-secretion coupling. Modulation of the RRP and of the efficacy of release thus both contribute to the enhancement of transmitter release by HFS.

scholarly journals Arf6 regulates the cycling and the readily releasable pool of synaptic vesicles at hippocampal synapse

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Erica Tagliatti ◽  
Manuela Fadda ◽  
Antonio Falace ◽  
Fabio Benfenati ◽  
Anna Fassio
Keyword(s):  
Plasma Membrane ◽  
Synaptic Vesicles ◽  
Small Gtpase ◽  
Endosomal Sorting ◽  
Releasable Pool ◽  
Readily Releasable Pool ◽  
Early Endosomes ◽  
Hippocampal Synapses ◽  
Activity Dependent ◽  
Adp Ribosylation Factor

Recycling of synaptic vesicles (SVs) is a fundamental step in the process of neurotransmission. Endocytosed SV can travel directly into the recycling pool or recycle through endosomes but little is known about the molecular actors regulating the switch between these SV recycling routes. ADP ribosylation factor 6 (Arf6) is a small GTPase known to participate in constitutive trafficking between plasma membrane and early endosomes. Here, we have morphologically and functionally investigated Arf6-silenced hippocampal synapses and found an activity dependent accumulation of synaptic endosome-like organelles and increased release-competent docked SVs. These features were phenocopied by pharmacological blockage of Arf6 activation. The data reveal an unexpected role for this small GTPase in reducing the size of the readily releasable pool of SVs and in channeling retrieved SVs toward direct recycling rather than endosomal sorting. We propose that Arf6 acts at the presynapse to define the fate of an endocytosed SV.

scholarly journals Synaptotagmin-1 and -7 Are Redundantly Essential for Maintaining the Capacity of the Readily-Releasable Pool of Synaptic Vesicles

PLoS Biology ◽  
2015 ◽  
Vol 13 (10) ◽  
pp. e1002267 ◽  
Author(s):  
Taulant Bacaj ◽  
Dick Wu ◽  
Jacqueline Burré ◽  
Robert C. Malenka ◽  
Xinran Liu ◽  
...  
Keyword(s):  
Synaptic Vesicles ◽  
Releasable Pool ◽  
Readily Releasable Pool ◽  
Synaptotagmin 1

A Simple Depletion Model of the Readily Releasable Pool of Synaptic Vesicles Cannot Account for Paired-Pulse Depression

2007 ◽  
Vol 97 (1) ◽  
pp. 948-950 ◽  
Author(s):  
Jane M. Sullivan
Keyword(s):  
Synaptic Vesicles ◽  
Hippocampal Neurons ◽  
Synaptic Activity ◽  
Excitatory Synapses ◽  
Short Term ◽  
Paired Pulse ◽  
Short Term Plasticity ◽  
Releasable Pool ◽  
Readily Releasable Pool ◽  
Paired Pulse Depression

Paired-pulse depression (PPD) is a form of short-term plasticity that plays a central role in processing of synaptic activity and is manifest as a decrease in the size of the response to the second of two closely timed stimuli. Despite mounting evidence to the contrary, PPD is still commonly thought to reflect depletion of the pool of synaptic vesicles available for release in response to the second stimulus. Here it is shown that PPD cannot be accounted for by depletion at excitatory synapses made by hippocampal neurons because PPD is unaffected by changes in the fraction of the readily releasable pool (RRP) released by the first of a pair of pulses.

scholarly journals β-Adrenergic Receptors/Epac Signaling Increases the Size of the Readily Releasable Pool of Synaptic Vesicles Required for Parallel Fiber LTP

2020 ◽  
Vol 40 (45) ◽  
pp. 8604-8617
Author(s):  
Ricardo Martín ◽  
Nuria García-Font ◽  
Alberto Samuel Suárez-Pinilla ◽  
David Bartolomé-Martín ◽  
José Javier Ferrero ◽  
...  
Keyword(s):  
Synaptic Vesicles ◽  
Adrenergic Receptors ◽  
Parallel Fiber ◽  
Releasable Pool ◽  
Readily Releasable Pool ◽  
Β Adrenergic Receptors ◽  
Epac Signaling

scholarly journals Endogenous Rho-Kinase Signaling Maintains Synaptic Strength by Stabilizing the Size of the Readily Releasable Pool of Synaptic Vesicles

2012 ◽  
Vol 32 (1) ◽  
pp. 68-84 ◽  
Author(s):  
D. Gonzalez-Forero ◽  
F. Montero ◽  
V. Garcia-Morales ◽  
G. Dominguez ◽  
L. Gomez-Perez ◽  
...  
Keyword(s):  
Synaptic Vesicles ◽  
Rho Kinase ◽  
Synaptic Strength ◽  
Kinase Signaling ◽  
Releasable Pool ◽  
Readily Releasable Pool

scholarly journals The Bruchpilot cytomatrix determines the size of the readily releasable pool of synaptic vesicles

2013 ◽  
Vol 202 (4) ◽  
pp. 667-683 ◽  
Author(s):  
Tanja Matkovic ◽  
Matthias Siebert ◽  
Elena Knoche ◽  
Harald Depner ◽  
Sara Mertel ◽  
...  
Keyword(s):  
Synaptic Vesicles ◽  
Circular Array ◽  
Membrane Domain ◽  
Releasable Pool ◽  
Readily Releasable Pool ◽  
Family Protein ◽  
Biochemical Identification ◽  
Macromolecular Architecture ◽  
Bar Formation ◽  
Ca2 Channels

Synaptic vesicles (SVs) fuse at a specialized membrane domain called the active zone (AZ), covered by a conserved cytomatrix. How exactly cytomatrix components intersect with SV release remains insufficiently understood. We showed previously that loss of the Drosophila melanogaster ELKS family protein Bruchpilot (BRP) eliminates the cytomatrix (T bar) and declusters Ca2+ channels. In this paper, we explored additional functions of the cytomatrix, starting with the biochemical identification of two BRP isoforms. Both isoforms alternated in a circular array and were important for proper T-bar formation. Basal transmission was decreased in isoform-specific mutants, which we attributed to a reduction in the size of the readily releasable pool (RRP) of SVs. We also found a corresponding reduction in the number of SVs docked close to the remaining cytomatrix. We propose that the macromolecular architecture created by the alternating pattern of the BRP isoforms determines the number of Ca2+ channel-coupled SV release slots available per AZ and thereby sets the size of the RRP.

scholarly journals The readily-releasable pool dynamically regulates multivesicular release

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jada H Vaden ◽  
Gokulakrishna Banumurthy ◽  
Eugeny S Gusarevich ◽  
Linda Overstreet-Wadiche ◽  
Jacques I Wadiche
Keyword(s):  
Molecular Mechanisms ◽  
Brain Slices ◽  
Site Occupancy ◽  
Fundamental Property ◽  
Brain Regions ◽  
Synaptic Function ◽  
Vesicle Release ◽  
Release Probability ◽  
Releasable Pool ◽  
Readily Releasable Pool

The number of neurotransmitter-filled vesicles released into the synaptic cleft with each action potential dictates the reliability of synaptic transmission. Variability of this fundamental property provides diversity of synaptic function across brain regions, but the source of this variability is unclear. The prevailing view is that release of a single (univesicular release, UVR) or multiple vesicles (multivesicular release, MVR) reflects variability in vesicle release probability, a notion that is well-supported by the calcium-dependence of release mode. However, using mouse brain slices, we now demonstrate that the number of vesicles released is regulated by the size of the readily-releasable pool, upstream of vesicle release probability. Our results point to a model wherein protein kinase A and its vesicle-associated target, synapsin, dynamically control release site occupancy to dictate the number of vesicles released without altering release probability. Together these findings define molecular mechanisms that control MVR and functional diversity of synaptic signaling.

Sign in / Sign up

Export Citation Format

Share Document