Evidence Indicating Release of the Contents of Synaptic Vesicles Distal to the Synaptic Cleft

1966 ◽  
Vol 85 (3) ◽  
pp. 475
Author(s):  
Paul R. Burton
Keyword(s):  
Synaptic Vesicles ◽  
Synaptic Cleft

Evaluation of hippocampus in rhesus monkeys after chronic (1-year) inhalation exposure to marijuana: I. Electron microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 398-399
Author(s):  
A.M. Andrews ◽  
S.W. Wilson ◽  
A.C. Scallet ◽  
S.F. Ali ◽  
J. Bailey ◽  
...  
Keyword(s):  
Synaptic Vesicles ◽  
Rhesus Monkeys ◽  
Low Dose ◽  
Inhalation Exposure ◽  
Synaptic Cleft ◽  
High Dose ◽  
Withdrawal Time ◽  
Treatment Groups ◽  
Ultrastructural Evidence ◽  
Male Rhesus

Exposure of rhesus monkeys (Macaca mulatta) to marijuana via inhalation or to intravenous delta-9-tetrahydrocannabinol (THC), reportedly caused ultrastructural evidence of increased synaptic width. Chronic marijuana smoke in a single rhesus monkey examined after a six month withdrawal time caused ultrastructure changes in the septal, hippocampal and amygdala regions; the synaptic cleft was widened, electron opaque material was found in the cleft and in the pre- and postsynaptic regions, with some clumping of the synaptic vesicles. The objective of our study was to assess neuropathological alterations produced by chronic inhalation of marijuana smoke.Nineteen male rhesus monkeys, 3-5 years of age and weighing 3-8 kg, were divided into four treatment groups: a) sham control, b) placebo smoke (7 days/ week) c) low dose marijuana (2 times/week with 5 days/week sham) and d) high dose marijuana (7 times/week). A smoke exposure consisted of smoke from one cigarette (2.6% THC) burned down to 10 mm butt length. Smoke was administered via smoke generator (ADL II, Arthur D. Little, Inc. Cambridge, MA) and nose-mouth only masks (local production) equipped with one-way valves.

scholarly journals The Fine Structure of Synapses in the Ciliary Ganglion of the Chick

1960 ◽  
Vol 7 (1) ◽  
pp. 31-36 ◽  
Author(s):  
A. J. de Lorenzo
Keyword(s):  
Fine Structure ◽  
Synaptic Vesicles ◽  
Ganglion Cells ◽  
Single Cells ◽  
Synaptic Cleft ◽  
Structural Features ◽  
Ciliary Ganglion ◽  
Single Axon ◽  
Electron Microscopes ◽  
Electron Microscope Image

Ciliary ganglia of chick embryos and newly hatched chicks were examined in the light and electron microscopes. Particular attention was given to the fine structure of calyciform synapses, which are characteristically found in ciliary ganglia of birds. The calyciform endings are characterized by large expansions of the presynaptic axons upon ganglion cells, and the terminal processes extend over a considerable area of the cell surface. Often, indeed they appear to envelop the cell. In the electron microscope image, the appositional membranes are separated by a space about 300 to 400 A wide; i.e., the synaptic cleft. At irregularly spaced regions, the appositional membranes show areas of increased density. The presynaptic processes contain clusters of synaptic vesicles, localized at these dense regions. Thus the fine structure complex typical of other synapses is evident. The unique structural features of this synapse are as follows: (a) The calyx or presynaptic terminal derives from a single axon, does not arborize, and terminates upon a single ganglion cell. Thus, unlike the classical bouton terminal, this represents an anatomical device for firing single cells by single axons. (b) The surface area in contiguity, i.e., the area of appositional membranes, is far more extensive than the bouton terminal. The fine structure of this synapse is compared with others, for example, the classical boutons terminaux and purely electrical synapses, in an attempt to correlate fine structure with function.

Neurotransmitter Release

2017 ◽  
Author(s):  
Peggy Mason
Keyword(s):  
Plasma Membrane ◽  
Synaptic Vesicle ◽  
Active Zone ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Synaptic Cleft ◽  
Fusion Pore ◽  
Synaptic Membrane ◽  
Specialized Region ◽  
Synaptic Vesicle Fusion

The biochemical and physiological processes of neurotransmitter release from an active zone, a specialized region of synaptic membrane, are examined. Synaptic vesicles containing neurotransmitters are docked at the active zone and then primed for release by SNARE complexes that bring them into extreme proximity to the plasma membrane. Entry of calcium ions through voltage-gated calcium channels triggers synaptic vesicle fusion with the synaptic terminal membrane and the consequent diffusion of neurotransmitter into the synaptic cleft. Release results when the fusion pore bridging the synaptic vesicle and plasma membrane widens and neurotransmitter from the inside of the synaptic vesicle diffuses into the synaptic cleft. Membrane from the active zone membrane is endocytosed, and synaptic vesicle proteins are then reassembled into recycled synaptic vesicles, allowing for more rounds of neurotransmitter release.

Putative duality of presynaptic events

2016 ◽  
Vol 27 (4) ◽  
pp. 377-383 ◽  
Author(s):  
Tatiana Borisova ◽  
Arsenii Borysov
Keyword(s):  
Synaptic Vesicles ◽  
Signal Transmission ◽  
Synaptic Cleft ◽  
Long Term Potentiation ◽  
Nerve Terminals ◽  
Chemical Synapse ◽  
Excitatory Neurotransmitter ◽  
Glutamate Concentration ◽  
Nerve Signal ◽  
Compound Exocytosis

AbstractThe main structure in the brain responsible not only for nerve signal transmission but also for its simultaneous regulation is chemical synapse, where presynaptic nerve terminals are of considerable importance providing release of neurotransmitters. Analyzing transport of glutamate, the major excitatory neurotransmitter in the mammalian CNS, the authors suggest that there are two main relatively independent mechanisms at the presynaptic level that can influence the extracellular glutamate concentration, and so signaling, and its regulation. The first one is well-known precisely regulated compound exocytosis of synaptic vesicles containing neurotransmitters stimulated by membrane depolarization, which increases significantly glutamate concentration in the synaptic cleft and initiates glutamate signaling through postsynaptic glutamate receptors. The second one is permanent glutamate turnover across the plasma membrane that occurs without stimulation and is determined by simultaneous non-pathological transporter-mediated release of glutamate thermodynamically synchronized with uptake. Permanent glutamate turnover is responsible for maintenance of dynamic glutamatein/glutamateoutgradient resulting in the establishment of a flexible extracellular level of glutamate, which can be unique for each synapse because of dependence on individual presynaptic parameters. These two mechanisms, i.e. exocytosis and transporter-mediated glutamate turnover, are both precisely regulated but do not directly interfere with each other, because they have different intracellular sources of glutamate in nerve terminals for release purposes, i.e. glutamate pool of synaptic vesicles and the cytoplasm, respectively. This duality can set up a presynaptic base for memory consolidation and storage, maintenance of neural circuits, long-term potentiation, and plasticity. Arguments against this suggestion are also considered.

Identification of excitatory and inhibitory neuromuscular synapses in the crayfish thoracic deep flexor musculature

1981 ◽  
Vol 59 (3) ◽  
pp. 364-369
Author(s):  
R. L. Crabtree ◽  
R. G. Sherman
Keyword(s):  
Electron Microscopy ◽  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Synaptic Cleft ◽  
Nerve Terminals ◽  
Neuromuscular Synapses ◽  
Deep Flexors

Excitatory and inhibitory neuromuscular synapses in the thoracic deep flexors of the crayfish were examined using electron microscopy. Excitatory nerve terminals were found to have larger synaptic vesicles and a greater synaptic cleft distance than did inhibitory terminals. These results were confirmed by fixation enhancement of differences in synaptic vesicle morphology and the experimental depletion of vesicles in the excitatory nerve terminals.

scholarly journals Research progress on vesicle cycle and neurological disorders

2021 ◽  
Vol 24 ◽  
pp. 400-412
Author(s):  
Chengcheng Zhang ◽  
Li-Juan Zhu ◽  
Ce Chen
Keyword(s):  
Synaptic Vesicles ◽  
Dynamic Balance ◽  
Synaptic Cleft ◽  
Research Progress ◽  
Triggered Release ◽  
Neuropsychiatric Diseases ◽  
Protein Receptors ◽  
Vesicle Exocytosis ◽  
Vesicle Cycle ◽  
And Function

Neurons are special polarized cells whose synaptic vesicles release neurotransmitters into the synaptic cleft, acting on postsynaptic receptors and thus transmitting information from presynaptic to postsynaptic states. The integrity of the vesicle cycle is critical to the transmission of neural signals in the brain. According to the molecular mechanism of calcium-triggered release, the assembly of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) is required in the process of synaptic vesicle fusion and vesicle exocytosis. Many delicate steps are required to maintain the dynamic process of ‘release-recycle’, including intermediate processes and the dynamic balance of neurotransmission. Various neurodegenerative and neuropsychiatric diseases result from synaptic cycle dysfunction. This review of the relationships between the structure and function of synaptic vesicles in physiological and pathological conditions provides a theoretical basis for synaptic transmission and a novel avenue for the study of synaptic plasticity associated with mood disorders, highlighting potential targets for treating diseases.

Clathrin-Mediated Endocytosis in the Giant Reticulospinal Synapse in Lamprey

1999 ◽  
Vol 5 (S2) ◽  
pp. 1026-1027
Author(s):  
O. Shupliakov
Keyword(s):  
Synaptic Vesicles ◽  
Synaptic Cleft ◽  
Coated Vesicle ◽  
Asymmetric Structure ◽  
Chemical Synapse ◽  
Animal Cells ◽  
Binding Studies ◽  
Fusion Event ◽  
Vesicle Membrane

The chemical synapse is a key structure used by neurons to communicate with neighboring cells. This is an asymmetric structure composed of two elements. The presynaptic part contains small synaptic vesicles filled with neurotransmitter. In an active synapse synaptic vesicles fuse with the presynaptic membrane and release neurotransmitter into the synaptic cleft. This results in activation of receptor molecules and respective ion channels on the postsynaptic cell. After a fusion event, the vesicle membrane is retrieved to form a new vesicle. Clathrin-mediated endocytosis is one of the main pathways for synaptic vesicle recycling. It involves a series of steps that starts with a flat plasma membrane and ends with an internalized coated vesicle. Four distinct stages have been defined: (1) the assembly of the clathrin coat, (2) the invagination of the coated membrane into a pit, (3) the constriction of the coated pit, and (4) the fission reaction that liberates the coated vesicle (e.g. De Camilli and Takei, 1996; Brodin et al., 1997). Analysis of mutant yeast and animal cells have linked a number of proteins to each of these stages. Taken together with data from in vitro binding studies, these observations indicate the existence of a complex molecular network that regulate the endocytic reactions.

scholarly journals THE ULTRASTRUCTURE OF MAUTHNER CELL SYNAPSES AND NODES IN GOLDFISH BRAINS

1963 ◽  
Vol 19 (1) ◽  
pp. 159-199 ◽  
Author(s):  
J. David Robertson ◽  
Thomas S. Bodenheimer ◽  
David E. Stage
Keyword(s):  
Extracellular Matrix ◽  
Synaptic Vesicles ◽  
Matrix Material ◽  
Synaptic Cleft ◽  
Dense Material ◽  
Synaptic Membrane ◽  
Electrical Transmission ◽  
Mauthner Cell ◽  
Membrane Complex ◽  
Cell Processes

An electron microscope study of goldfish Mauthner cells is reported.1 The cell is covered by a synaptic bed ∼ 5 µ thick containing unusual amounts of extracellular matrix material in which synapses and clear glia processes are implanted. The preterminal synaptic neurites are closely invested by an interwoven layer of filament-containing satellite cell processes. The axoplasm of the club endings contains oriented mitochondria, neurofilaments, neurotubules, and relatively few synaptic vesicles. That of the boutons terminaux contains many unoriented mitochondria and is packed with synaptic vesicles and some glycogen but no neurofilaments or neurotubules. The bare axons of club endings are surrounded by a moderately abundant layer of matrix material. The synaptic membrane complex (SMC) in cross-section shows segments of closure of the synaptic cleft ∼ 0.2 to 0.5 µ long. These alternate with desmosome-like regions of about the same length in which the gap widens to ∼ 150 A and contains a condensed central stratum of dense material. Here, there are also accumulations of dense material in pre- and postsynaptic neuroplasm. The boutons show no such differentiation and the extracellular matrix is largely excluded around them. The axon cap is a dense neuropil of interwoven neural and glial elements free of myelin. It is covered by a closely packed layer of glia cells. The findings are interpreted as suggestive of electrical transmission in the club endings.

scholarly journals ULTRASTRUCTURE OF THE SPOON TYPE SYNAPTIC ENDINGS IN THE NUCLEUS VESTIBULARIS TANGENTIALIS OF THE CHICK

1967 ◽  
Vol 34 (2) ◽  
pp. 421-430 ◽  
Author(s):  
Raúl Hinojosa ◽  
J. David Robertson
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Synaptic Vesicles ◽  
Synaptic Cleft ◽  
Synaptic Membrane ◽  
Electrical Transmission ◽  
Membrane Complex ◽  
Pattern Characteristic ◽  
Oriented Parallel ◽  
Nucleus Vestibularis

The fine structure of the "spoon" type synaptic endings of the chick tangential nucleus was studied with the electron microscope. These endings often measure ∼18 µ in length by ∼3–4 µ in width. The axoplasm of the endings contains very few synaptic vesicles, a large number of neurofilaments oriented parallel to the long axis of the nerve fiber, and microtubules and numerous mitochondria. The synaptic membrane complex shows areas of localized occlusion of the synaptic cleft with the formation of an external compound membrane. It has not been decided whether these areas have a disc shape; their length measures between 0.04 and 0.47 µ. The five-layer pattern characteristic of an external compound membrane is shown in specimens fixed with formalin—OsO4, glutaraldehyde—acrolein—OsO4, and acrolein KMnO4 but it does not appear in the glutaraldehyde-OsO4-fixed specimens. The over-all thickness of the external compound membrane varies depending upon the fixative used. The synaptic clefts in the regions between the external compound membrane discs are widened and measure ∼300 A. A condensation of dense material occurs in pre- and postsynaptic cytoplasms all along the synaptic membrane complex. The morphological relationships described in the spoon endings are suggestive of electrical transmission.

Neuronal functions of clathrin-associated endocytic sorting adaptors – from molecules to disease

Neuroforum ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Natalia L. Kononenko ◽  
Volker Haucke
Keyword(s):  
Synaptic Vesicles ◽  
Neurological Diseases ◽  
Adaptor Proteins ◽  
Synaptic Cleft ◽  
Synaptic Function ◽  
Multiple Roles ◽  
Endocytic Sorting ◽  
The Central Nervous System ◽  
Neuronal Functions ◽  
Synaptic Vesicle Fusion

AbstractCommunication in the central nervous system is based on the transmission of electrical signals at specialized junctions between nerve cells termed synapses. During chemical neurotransmission, tiny membrane spheres called synaptic vesicles that are packed with neurotransmitters elicit a postsynaptic response by fusing with the presynaptic membrane and releasing their content into the synaptic cleft. Synaptic vesicle fusion is followed by the reuptake of the membrane by endocytosis and the local reformation of functional synaptic vesicles within the presynaptic compartment to sustain further rounds of neurotransmitter release. Here, we provide an overview of the clathrin-associated endocytic adaptor proteins that help to sort and recycle synaptic vesicles during presynaptic activity. These adaptors also serve additional functions in the turnover of defective or aged synaptic components and in the retrograde axonal transport of important signaling molecules by regulating the formation or transport of autophagosomes. Endocytic adaptors thus play multiple roles in the maintenance of synaptic function. Defects in their expression or function can lead to neurodegenerative and neurological diseases.

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