Electrical Synapses – Gap Junctions in the Brain

2006 ◽  
pp. 99-128 ◽  
Author(s):  
Carola Meier ◽  
Rolf Dermietzel
Keyword(s):  
Gap Junctions ◽  
Electrical Synapses ◽  
The Brain

scholarly journals Electrical synaptic transmission requires a postsynaptic scaffolding protein

2020 ◽  
Author(s):  
Abagael M. Lasseigne ◽  
Fabio A. Echeverry ◽  
Sundas Ijaz ◽  
Jennifer Carlisle Michel ◽  
E. Anne Martin ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Gap Junctions ◽  
Functional Organization ◽  
Scaffolding Protein ◽  
Scaffolding Proteins ◽  
Electrical Transmission ◽  
Critical Function ◽  
Electrical Synapses ◽  
Intercellular Channels ◽  
Chemical Synapses

SUMMARYElectrical synaptic transmission relies on neuronal gap junctions containing channels constructed by Connexins. While at chemical synapses neurotransmitter-gated ion channels are critically supported by scaffolding proteins, it is unknown if channels at electrical synapses require similar scaffold support. Here we investigated the functional relationship between neuronal Connexins and Zonula Occludens 1 (ZO1), an intracellular scaffolding protein localized to electrical synapses. Using model electrical synapses in zebrafish Mauthner cells, we demonstrated that ZO1 is required for robust synaptic Connexin localization, but Connexins are dispensable for ZO1 localization. Disrupting this hierarchical ZO1/Connexin relationship abolishes electrical transmission and disrupts Mauthner-cell-initiated escape responses. We found that ZO1 is asymmetrically localized exclusively postsynaptically at neuronal contacts where it functions to assemble intercellular channels. Thus, forming functional neuronal gap junctions requires a postsynaptic scaffolding protein. The critical function of a scaffolding molecule reveals an unanticipated complexity of molecular and functional organization at electrical synapses.

Gap junctions in the brain: where, what type, how many and why?

1993 ◽  
Vol 16 (5) ◽  
pp. 186-192 ◽  
Author(s):  
Rolf Dermietzel ◽  
David C. Spray
Keyword(s):  
Gap Junctions ◽  
The Brain

Gap Junctions in the Brain

2013 ◽  
pp. 3-17 ◽  
Author(s):  
Armin Zlomuzica ◽  
Sonja Binder ◽  
Ekrem Dere
Keyword(s):  
Gap Junctions ◽  
The Brain

scholarly journals JUNCTIONS BETWEEN INTIMATELY APPOSED CELL MEMBRANES IN THE VERTEBRATE BRAIN

1969 ◽  
Vol 40 (3) ◽  
pp. 648-677 ◽  
Author(s):  
M. W. Brightman ◽  
T. S. Reese
Keyword(s):  
Gap Junctions ◽  
Tight Junctions ◽  
Preparative Method ◽  
Uranyl Acetate ◽  
Structural Basis ◽  
Ependymal Cells ◽  
Cerebral Ventricles ◽  
Vertebrate Brain ◽  
Intercellular Movement ◽  
The Brain

Certain junctions between ependymal cells, between astrocytes, and between some electrically coupled neurons have heretofore been regarded as tight, pentalaminar occlusions of the intercellular cleft. These junctions are now redefined in terms of their configuration after treatment of brain tissue in uranyl acetate before dehydration. Instead of a median dense lamina, they are bisected by a median gap 20–30 A wide which is continuous with the rest of the interspace. The patency of these "gap junctions" is further demonstrated by the penetration of horseradish peroxidase or lanthanum into the median gap, the latter tracer delineating there a polygonal substructure. However, either tracer can circumvent gap junctions because they are plaque-shaped rather than complete, circumferential belts. Tight junctions, which retain a pentalaminar appearance after uranyl acetate block treatment, are restricted primarily to the endothelium of parenchymal capillaries and the epithelium of the choroid plexus. They form rows of extensive, overlapping occlusions of the interspace and are neither circumvented nor penetrated by peroxidase and lanthanum. These junctions are morphologically distinguishable from the "labile" pentalaminar appositions which appear or disappear according to the preparative method and which do not interfere with the intercellular movement of tracers. Therefore, the interspaces of the brain are generally patent, allowing intercellular movement of colloidal materials. Endothelial and epithelial tight junctions occlude the interspaces between blood and parenchyma or cerebral ventricles, thereby constituting a structural basis for the blood-brain and blood-cerebrospinal fluid barriers.

scholarly journals The gap junction blocker mefloquine impairs sleep-dependent declarative memory consolidation in humans

2019 ◽  
Author(s):  
Gordon B. Feld ◽  
Hong-Viet Ngo ◽  
Ernesto Durán ◽  
Sandra Gebhardt ◽  
Lisa Kleist ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Memory Consolidation ◽  
Information Transfer ◽  
Declarative Memory ◽  
Electrical Coupling ◽  
Procedural Memory ◽  
Neuronal Firing ◽  
Electrical Synapses ◽  
Brain Functions ◽  
Healthy Humans

AbstractDuring sleep, the time-compressed replay of engrams acquired during preceding wakefulness drives memory consolidation. We demonstrate in healthy humans that direct electrical coupling between neurons via gap junctions, i.e., electrical synapses, contributes to this beneficial effect of sleep. Twenty male participants learned a declarative word-pair task and a procedural finger sequence tapping task before receiving the antimalarial mefloquine that is known to block electrical synapses. Retrieval was tested after a retention interval of approximately 20.5 hours that included nocturnal sleep. As predicted, mefloquine given before sleep impaired the retention of declarative memory. In contrast, this effect was absent in control groups, which stayed awake or received mefloquine after sleep. Irrespective of sleep or administration time, mefloquine enhanced retention performance on the procedural memory control task. We conclude that sleep-dependent processes relying on electrical neuronal coupling enable hippocampus-dependent declarative memory consolidation, presumably via time-compressed hippocampal replay of memory traces within sharp-wave/ripple complexes. The recruitment of this understudied form of neuronal information transfer may be necessary to achieve fast-paced memory reprocessing during sleep. Considering that drugs targeting neurochemical synapses have recently fallen short of substantially advancing the treatment of memory impairments in Alzheimer’s disease, schizophrenia or during normal aging, unraveling the contribution of gap junctions to sleep-dependent declarative memory formation can be expected to open new therapeutic avenues.Significance statementSleep supports the strengthening and transformation of memory content via the active replay of previously encoded engrams. Surprisingly, blocking neurochemical synaptic transmission does not impair this function of sleep. Here we demonstrate that the direct electrical coupling between neurons via electrical synapses (gap junctions) is essential for the sleep-dependent formation of declarative memory, i.e., memory for episodes and facts. These findings are in line with the assumption that electrical synapses enable time-compressed neuronal firing patterns that emerge during sleep and drive declarative memory consolidation. Electrical synapses have so far not been linked to higher-order brain functions in humans; their contribution to sleep-dependent memory processing may provide a novel target for sleep-related clinical interventions.

Possible transmitter functions of acetylcholine and an RFamide-like substance in Sagitta (Chaetognatha)

1987 ◽  
Vol 230 (1258) ◽  
pp. 1-14 ◽  
Keyword(s):  
Gap Junctions ◽  
Spontaneous Activity ◽  
Muscle Fibres ◽  
Sensory Organs ◽  
Iontophoretic Application ◽  
Immunocytochemical Studies ◽  
The Brain

The locomotor muscle fibres of the chaetognath Sagitta are probably multiply innervated and, although linked by numerous gap junctions, do not appear to be coupled electrically. Acetylcholine evokes contraction of the locomotor muscle; iontophoretic application of acetylcholine evokes membrane depolarizations and a series of spikes resembling those seen during spontaneous activity. Both effects are reversibly abolished by (+)-tubocurarine. Acetylcholinesterase is found associated with the sarcolemmata, and it is suggested that acetylcholine is a possible candidate for the neuromuscular transmitter. Immunocytochemical studies with antisera raised against the sequence Arg-Phe-amide (RFamide) show that many neurons in the brain and ventral ganglia contain an RFamide-like material. Some of these neurons are associated with the innervation of sensory organs; others may belong to coordinating systems. At present, these observations do not indicate the affinity of the Chaetognatha to any other invertebrate phylum.

scholarly journals Electrical synapses mediate synergism between pheromone and food odors in Drosophila melanogaster

2017 ◽  
Vol 114 (46) ◽  
pp. E9962-E9971 ◽  
Author(s):  
Sudeshna Das ◽  
Federica Trona ◽  
Mohammed A. Khallaf ◽  
Elisa Schuh ◽  
Markus Knaden ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Gap Junctions ◽  
Projection Neuron ◽  
Projection Neurons ◽  
Electrical Synapses ◽  
Synergistic Interactions ◽  
Food Odors ◽  
Synergistic Response ◽  
Input Level ◽  
Lateral Excitation

In Drosophila melanogaster, the sex pheromone produced by males, cis-vaccenyl acetate (cVA), evokes a stereotypic gender-specific behavior in both males and females. As Drosophila adults feed, mate, and oviposit on food, they perceive the pheromone as a blend against a background of food odors. Previous studies have reported that food odors enhance flies’ behavioral response to cVA, specifically in virgin females. However, how and where the different olfactory inputs interact has so far remained unknown. In this study, we elucidated the neuronal mechanism underlying the response at an anatomical, functional, and behavioral level. Our data show that in virgin females cVA and the complex food odor vinegar evoke a synergistic response in the cVA-responsive glomerulus DA1. This synergism, however, does not appear at the input level of the glomerulus, but is restricted to the projection neuron level only. Notably, it is abolished by a mutation in gap junctions in projection neurons and is found to be mediated by electrical synapses between excitatory local interneurons and projection neurons. As a behavioral consequence, we demonstrate that virgin females in the presence of vinegar become receptive more rapidly to courting males, while male courtship is not affected. Altogether, our results suggest that lateral excitation via gap junctions modulates odor tuning in the antennal lobe and drives synergistic interactions between two ecologically relevant odors, representing food and sex.

scholarly journals Electrical synaptic transmission in developing zebrafish: properties and molecular composition of gap junctions at a central auditory synapse

2014 ◽  
Vol 112 (9) ◽  
pp. 2102-2113 ◽  
Author(s):  
Cong Yao ◽  
Kimberly G. Vanderpool ◽  
Matthew Delfiner ◽  
Vanessa Eddy ◽  
Alexander G. Lucaci ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Gap Junctions ◽  
Developmental Stages ◽  
Neural Function ◽  
Electrical Transmission ◽  
Electrical Synapses ◽  
Connexin 36 ◽  
Auditory Responses ◽  
Electrophysiological Recordings ◽  
Chemical Synapses

In contrast to the knowledge of chemical synapses, little is known regarding the properties of gap junction-mediated electrical synapses in developing zebrafish, which provide a valuable model to study neural function at the systems level. Identifiable “mixed” (electrical and chemical) auditory synaptic contacts known as “club endings” on Mauthner cells (2 large reticulospinal neurons involved in tail-flip escape responses) allow exploration of electrical transmission in fish. Here, we show that paralleling the development of auditory responses, electrical synapses at these contacts become anatomically identifiable at day 3 postfertilization, reaching a number of ∼6 between days 4 and 9. Furthermore, each terminal contains ∼18 gap junctions, representing between 2,000 and 3,000 connexon channels formed by the teleost homologs of mammalian connexin 36. Electrophysiological recordings revealed that gap junctions at each of these contacts are functional and that synaptic transmission has properties that are comparable with those of adult fish. Thus a surprisingly small number of mixed synapses are responsible for the acquisition of auditory responses by the Mauthner cells, and these are likely sufficient to support escape behaviors at early developmental stages.

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