Nodes of ranvier

The bipolar disorder (BD) risk gene ANK3 encodes the scaffolding protein AnkyrinG (AnkG). In neurons, AnkG regulates polarity and ion channel clustering at axon initial segments and nodes of Ranvier. Disruption of neuronal AnkG causes BD-like phenotypes in mice. During development, AnkG is also expressed at comparable levels in oligodendrocytes and facilitates the efficient assembly of paranodal junctions. However, the physiological roles of glial AnkG in the mature nervous system, and its contributions to BD-like phenotypes, remain unexplored...

The neuronal cell adhesion molecule (NrCAM) is widely expressed and has important physiological functions in the nervous system across the lifespan, from axonal growth and guidance to spine and synaptic pruning, to organization of proteins at the nodes of Ranvier. NrCAM lies at the core of a functional protein network where multiple targets (including NrCAM itself) have been associated with schizophrenia. Here we investigated the effects of chronic unpredictable stress on latent inhibition, a measure of selective attention and learning which shows alterations in schizophrenia, in NrCAM knockout (KO) mice and their wild-type littermate controls (WT)...

Neural activity can increase the length of nodes of Ranvier (NOR) and slow impulse transmission; however, little is known about the biologically and clinically important recovery process. Sensory deprivation promotes neural plasticity in many phenomena, raising the question of whether recovery of NOR morphology is influenced by sensory deprivation. The results show that NOR gap length recovery in mouse optic nerve was not affected significantly by binocular visual deprivation imposed by maintaining mice in 24hr dark for 30 days compared to mice recovering under normal visual experience...

OBJECTIVES: In 2015, a new term "nodopathy" was introduced to represent a group of neuropathy because of autoantibodies at the node of Ranvier and paranodal area. This review was conducted to highlight the electrophysiologic characteristics of acute and chronic nodopathies by the newly introduced term: "nodal conduction block (CB); CB without temporal dispersion or slow nerve conduction velocity" and by introducing a new term: "internodal CB; CB with temporal dispersion or/and slow nerve conduction velocity"...

Due to its proximity to the axon initial segment (AIS), the paranode of the first myelin segment can influence the threshold for action potentials and how a neuron participates in a neuronal circuit. Using serial section electron microscopy, we examined its three-dimensional (3D) organization in the ventral horn of the mouse spinal cord. The myelin loops of postnatal day 18 mice resemble those at the node of Ranvier. However, in 3-month-old mice, 13 of 22 para-AIS showed 4 types of alteration: (A) A cytoplasmic foot process, with ultrastructural characteristics of an astrocyte, was interposed between the axolemma and the myelin loops...

Anxiety disorders are prevalent mental disorders. Their predisposition involves a combination of genetic and environmental risk factors, such as psychosocial stress. Myelin plasticity was recently associated with chronic stress in several mouse models. Furthermore, we found that changes in both myelin thickness and node of Ranvier morphology after chronic social defeat stress are influenced by the genetic background of the mouse strain. To understand cellular and molecular effects of stress-associated myelin plasticity, we established an oligodendrocyte (OL) model consisting of OL primary cell cultures isolated from the C57BL/6NCrl (B6; innately non-anxious and mostly stress-resilient strain) and DBA/2NCrl (D2; innately anxious and mostly stress-susceptible strain) mice...

Tactile discrimination, the ability to differentiate objects' physical properties such as texture, shape, and edges, is essential for environmental exploration, social interaction, and early childhood development. This ability heavily relies on Merkel cell-neurite complexes (MNCs), the tactile end-organs enriched in the fingertips of humans and the whisker hair follicles of non-primate mammals. Although recent studies have advanced our knowledge on mechanical transduction in MNCs, it remains unknown how tactile signals are encoded at MNCs...

In mammals, thick axonal calibers wrapped with heavy myelin sheaths are prevalent in the auditory nervous system. These features are crucial for fast traveling of nerve impulses with minimal attenuation required for sound signal transmission. In particular, the long-range projections from the cochlear nucleus - the axons of globular bush cells (GBCs) - to the medial nucleus of the trapezoid body (MNTB) are tonotopically organized. However, it remains controversial in gerbils and mice whether structural and functional adaptations are present among the GBC axons targeting different MNTB frequency regions...

Axons undergo striking changes in their content and distribution of cell adhesion molecules (CAMs) and ion channels during myelination that underlies the switch from continuous to saltatory conduction. These changes include the removal of a large cohort of uniformly distributed CAMs that mediate initial axon-Schwann cell interactions and their replacement by a subset of CAMs that mediate domain-specific interactions of myelinated fibers. Here, using rodent models, we examine the mechanisms and significance of this removal of axonal CAMs...

Axons of globular bushy cells in the cochlear nucleus convey hyper-accurate signals to the superior olivary complex, the initial site of binaural processing via comparably thick axons and the calyx of the Held synapse. Bushy cell fibers involved in hyper-accurate binaural processing of low-frequency sounds are known to have an unusual internode length-to-axon caliber ratio (L/d) correlating with higher conduction velocity and superior temporal precision of action potentials. How the L/d-ratio develops and what determines this unusual myelination pattern is unclear...

BACKGROUND AND PURPOSE: Anti-neurofascin-155 (NF155) antibody is one of the autoantibodies associated with autoimmune nodopathy. We aimed to determine the clinical features of South Korean patients with anti-NF155-antibody-positive autoimmune nodopathy. METHODS: The sera of 68 patients who fulfilled the diagnostic criteria for chronic inflammatory demyelinating polyneuropathy (CIDP) were tested for anti-NF155 antibodies using a cell-based assay (CBA) and enzyme-linked immunosorbent assay (ELISA)...

In this paper, for the first time, we showed that an Internode Segment (INS) of a myelinated axon acts as a lowpass filter, and its filter characteristics depend on the number of myelin turns. Consequently, we showed how the representability of a neural signal could be altered with myelin loss in pathological conditions involving demyelinating diseases. Contrary to the traditionally held viewpoint that myelin geometry of an INS is optimised for maximising Conduction Velocity (CV) of Action Potential (AP), our theory provides an alternative viewpoint that myelin geometry of an INS is optimised for maximizing representability of the stimuli a fibre is meant to carry...

Diffuse axonal injury (DAI) is a significant feature of traumatic brain injury (TBI) across all injury severities and is driven by the primary mechanical insult and secondary biochemical injury phases. Axons comprise an outer cell membrane, the axolemma which is anchored to the cytoskeletal network with spectrin tetramers and actin rings. Neurofilaments act as space-filling structural polymers that surround the central core of microtubules, which facilitate axonal transport. TBI has differential effects on these cytoskeletal components, with axons in the same white matter tract showing a range of different cytoskeletal and axolemma alterations with different patterns of temporal evolution...

In acute inflammatory demyelinating polyneuropathy (AIDP), myelin vesiculation mediated by complement activation contributes to nerve injury. Macrophage infiltration of the spinal roots has been demonstrated in AIDP, but its pathological significance remains uncertain. The present study aimed to investigate the role of macrophages in the pathogenic sequence of AIDP. A rabbit model of AIDP was induced by immunization with galactocerebroside. Immunostaining was performed to localize the macrophages and myelin injury...

In acute inflammatory demyelinating polyneuropathy (AIDP), myelin vesiculation mediated by complement activation contributes to nerve injury. Macrophage infiltration of the spinal roots has been demonstrated in AIDP, but its pathological significance remains uncertain. The present study aimed to investigate the role of macrophages in the pathogenic sequence of AIDP. A rabbit model of AIDP was induced by immunization with galactocerebroside. Immunostaining was performed to localize the macrophages and myelin injury...

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Oligodendrocytes are the primary producers of many extracellular matrix (ECM)-related proteins found in the CNS. Therefore, oligodendrocytes play a critical role in the determination of brain stiffness, node of Ranvier formation, perinodal ECM deposition, and perineuronal net formation, all of which depend on the ECM. Nevertheless, the transcription factors that control ECM-related gene expression in oligodendrocytes remain unknown. Here, we found that the transcription factor Osterix (also known as Sp7) binds in proximity to genes important for CNS ECM and node of Ranvier formation and mediates their expression...

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is recognized as a syndrome caused by multiple pathologies. Since the 2010s, it has been clarified that autoantibodies against membranous proteins localized in the nodes of Ranvier and paranodes are positive in subsets of CIDP patients, leading to proposing a new disease concept called autoimmune nodopathies, which is independent of CIDP, in the revised international CIDP guidelines. This article reviews the significance of these autoantibodies, especially anti-neurofascin 155 and anti-contactin 1 antibodies, which have been the most prevalent and achieved a higher degree of consensus...

BACKGROUND: Homozygous CD59-deficient patients manifest with recurrent peripheral neuropathy resembling Guillain-Barré syndrome (GBS), hemolytic anemia and recurrent strokes. Variable mutations in CD59 leading to loss of function have been described and, overall, 17/18 of patients with any mutation presented with recurrent GBS. Here we determine the localization and possible role of membrane-bound complement regulators, including CD59, in the peripheral nervous systems (PNS) of mice and humans...

The Contactin-associated protein 1 (Cntnap1) mouse mutants fail to establish proper axonal domains in myelinated axons. Human CNTNAP1 mutations are linked to hypomyelinating neuropathy-3, which causes severe neurological deficits. To understand the human neuropathology and to model human CNTNAP1C323R and CNTNAP1R764C mutations, we generated Cntnap1C324R and Cntnap1R765C mouse mutants, respectively. Both Cntnap1 mutants show weight loss, reduced nerve conduction, and progressive motor dysfunction. The paranodal ultrastructure shows everted myelin loops and the absence of axo-glial junctions...