scholarly journals The Axonal Cytoskeleton and the Assembly of Nodes of Ranvier

2017 ◽  
Vol 24 (2) ◽  
pp. 104-110 ◽  
Author(s):  
Aniket Ghosh ◽  
Diane L. Sherman ◽  
Peter J. Brophy
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Protein Complexes ◽  
Nerve Impulse ◽  
Nodes Of Ranvier ◽  
Axonal Membrane ◽  
Voltage Gated Sodium Channels ◽  
The Central Nervous System ◽  
High Concentrations ◽  
Surface Domains

Vertebrate nervous systems rely on rapid nerve impulse transmission to support their complex functions. Fast conduction depends on ensheathment of nerve axons by myelin-forming glia and the clustering of high concentrations of voltage-gated sodium channels (Nav) in the axonal gaps between myelinated segments. These gaps are the nodes of Ranvier. Depolarization of the axonal membrane initiates the action potential responsible for impulse transmission, and the Nav help ensure that this is restricted to nodes. In the central nervous system, the formation of nodes and the clustering of Nav in nodal complexes is achieved when oligodendrocytes extend their processes and ultimately ensheath axons with myelin. However, the mechanistic relationship between myelination and the formation of nodal complexes is unclear. Here we review recent work in the central nervous system that shows that axons, by assembling distinct cytoskeletal interfaces, are not only active participants in oligodendrocyte process migration but are also significant contributors to the mechanisms by which myelination causes Nav clustering. We also discuss how the segregation of membrane protein complexes through their interaction with distinct cytoskeletal complexes may play a wider role in establishing surface domains in axons.

scholarly journals Glial and neuronal isoforms of Neurofascin have distinct roles in the assembly of nodes of Ranvier in the central nervous system

2008 ◽  
Vol 181 (7) ◽  
pp. 1169-1177 ◽  
Author(s):  
Barbara Zonta ◽  
Steven Tait ◽  
Shona Melrose ◽  
Heather Anderson ◽  
Sheila Harroch ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Sodium Channels ◽  
Molecular Mechanisms ◽  
Nerve Impulse ◽  
Node Of Ranvier ◽  
Nodes Of Ranvier ◽  
Additional Function ◽  
The Central Nervous System ◽  
Adhesion Complex

Rapid nerve impulse conduction in myelinated axons requires the concentration of voltage-gated sodium channels at nodes of Ranvier. Myelin-forming oligodendrocytes in the central nervous system (CNS) induce the clustering of sodium channels into nodal complexes flanked by paranodal axoglial junctions. However, the molecular mechanisms for nodal complex assembly in the CNS are unknown. Two isoforms of Neurofascin, neuronal Nfasc186 and glial Nfasc155, are components of the nodal and paranodal complexes, respectively. Neurofascin-null mice have disrupted nodal and paranodal complexes. We show that transgenic Nfasc186 can rescue the nodal complex when expressed in Nfasc−/− mice in the absence of the Nfasc155–Caspr–Contactin adhesion complex. Reconstitution of the axoglial adhesion complex by expressing transgenic Nfasc155 in oligodendrocytes also rescues the nodal complex independently of Nfasc186. Furthermore, the Nfasc155 adhesion complex has an additional function in promoting the migration of myelinating processes along CNS axons. We propose that glial and neuronal Neurofascins have distinct functions in the assembly of the CNS node of Ranvier.

Effect of Nicotine on the Synapse of the Central Nervous System

1958 ◽  
Vol 192 (3) ◽  
pp. 447-452 ◽  
Author(s):  
Sadayuki F. Takagi ◽  
Yutaka Oomura
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Synaptic Transmission ◽  
Reflex Activity ◽  
Synaptic Delay ◽  
Synaptic Potential ◽  
Before And After ◽  
The Central Nervous System ◽  
High Concentrations

The effect of nicotine on synaptic transmission in the frog and cat spinal cord was studied. Both a regular wick electrode and a microelectrode of the Ling-Gerard type were used. The reflex activity of the bullfrog spinal cord is facilitated by 0.01% nicotine solution, but is depressed and abolished by 0.1% solution. In the cat, intravenous administration of 150 mg/kg fails to block reflex activity, but topical application does block. The intracellular potential, of both frog and cat motoneurones, shows no change in the synaptic potential after application of the drug, but the spike appears after a shorter synaptic delay and one or more additional spikes appear. When the synaptic delay becomes sufficiently short, however, all spikes suddenly disappear, leaving the still unchanged synaptic potential. Occasionally the synaptic delay is again increased just before the spike potentials disappear. The excitability of a frog motoneurone was measured, by a recording microelectrode, before and after nicotine application. The drug first increased and then decreases excitability. Epinephrine can restore a reflex discharge depressed or abolished by nicotine. It is concluded that high concentrations of nicotine block synaptic transmission in the central nervous system, acting on the cell body but not on the synaptic potential.

Voltage-gated sodium channels and pain

e-Neuroforum ◽  
2017 ◽  
Vol 23 (3) ◽  
Author(s):  
Carla Nau ◽  
Enrico Leipold
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Sodium Channels ◽  
Action Potentials ◽  
Afferent Pathways ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
The Central Nervous System

AbstractPainful stimuli are detected by specialized neurons, nociceptors, and are translated into action potentials, that are conducted along afferent pathways into the central nervous system, where they are conceived as pain. Voltage-gated sodium channels (Na

scholarly journals Role of Thrombin in Central Nervous System Injury and Disease

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 562
Author(s):  
Nathan A. Shlobin ◽  
Meirav Har-Even ◽  
Ze’ev Itsekson-Hayosh ◽  
Sagi Harnof ◽  
Chaim G. Pick
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Neurological Disease ◽  
Central Nervous System Tumors ◽  
Cell Protection ◽  
Low Concentrations ◽  
The Central Nervous System ◽  
High Concentrations ◽  
The Brain

Thrombin is a Na+-activated allosteric serine protease of the chymotrypsin family involved in coagulation, inflammation, cell protection, and apoptosis. Increasingly, the role of thrombin in the brain has been explored. Low concentrations of thrombin are neuroprotective, while high concentrations exert pathological effects. However, greater attention regarding the involvement of thrombin in normal and pathological processes in the central nervous system is warranted. In this review, we explore the mechanisms of thrombin action, localization, and functions in the central nervous system and describe the involvement of thrombin in stroke and intracerebral hemorrhage, neurodegenerative diseases, epilepsy, traumatic brain injury, and primary central nervous system tumors. We aim to comprehensively characterize the role of thrombin in neurological disease and injury.

scholarly journals The Structure and Conduction Velocity of the Medullated Nerve Fibres of Prawns

1941 ◽  
Vol 18 (1) ◽  
pp. 50-54 ◽  
Author(s):  
W. HOLMES ◽  
R. J. PUMPHREY ◽  
J. Z. YOUNG
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Conduction Velocity ◽  
Myelin Sheath ◽  
Axon Diameter ◽  
Relative Thickness ◽  
Nodes Of Ranvier ◽  
Nerve Fibres ◽  
The Central Nervous System ◽  
Myelinated Fibres

1. The structure of the myelinated fibres of prawns is described, and the homologies of the nucleated sheath which lies between the axon and the fatty layer discussed. 2. The relative thickness of the myelin sheath increases with decrease in total diameter of the fibre along a curve similar in shape to that found in vertebrates and earthworms. 3. Nodes of Ranvier are found in the sheaths of most fibres of a diameter greater than about 13µ 4. The nodes are similar to those in vertebrate nerves in that the myelin sheath is interrupted at the node. 5. The conduction velocity of fibres in the central nervous system of axon diameter 26µ and total diameter 35µ is between 18 and 23 m. per sec., a rate faster than is found in the "unmyelinated" fibres of similar size in other crustacea.

Retinoic acid modifies the pattern of cell differentiation in the central nervous system of neurula stage Xenopus embryos

Development ◽  
1991 ◽  
Vol 112 (4) ◽  
pp. 945-958 ◽  
Author(s):  
A. Ruiz i Altaba ◽  
T.M. Jessell
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Retinoic Acid ◽  
Cell Fate ◽  
Cell Types ◽  
Neural Cell ◽  
Xenopus Embryos ◽  
The Central Nervous System ◽  
High Concentrations ◽  
Neurula Stage

Neural cell markers have been used to examine the effect of retinoic acid (RA) on the development of the central nervous system (CNS) of Xenopus embryos. RA treatment of neurula stage embryos resulted in a concentration-dependent perturbation of anterior CNS development leading to a reduction in the size of the forebrain, midbrain and hindbrain. In addition the overt segmental organization of the hindbrain was abolished by high concentrations of RA. The regional expression of two cell-specific markers, the homeobox protein Xhox3 and the neurotransmitter serotonin was also examined in embryos exposed to RA. Treatment with RA caused a concentration-dependent change in the pattern of expression of Xhox3 and serotonin and resulted in the ectopic appearance of immunoreactive neurons in anterior regions of the CNS, including the forebrain. Collectively, our results extend previous studies by showing that RA treatment of embryos at the neurula stage inhibits the development of anterior regions of the CNS while promoting the differentiation of more posterior cell types. The relevance of these findings to the possible role of endogenous retinoids in the determination of neural cell fate and axial patterning is discussed.

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