| Regional modulation of neurofilament organization by myelination in normal axons. | |
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MedLine Citation:
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PMID: 7965044 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Previous studies in the hypomyelinating mouse mutant Trembler have suggested that demyelinating axons are smaller in caliber compared to normal axons, and that there are differences in the organization of axonal neurofilaments. In the normal PNS, however, the relationship between neurofilament organization and myelination has not been investigated extensively. In normal axons, only the initial segments, the nodes of Ranvier (approximately 1 micron), and the terminals are not covered by myelin. We took advantage of an unusual feature of the primary sensory neurons in the dorsal root ganglion, the relatively long nonmyelinated stem process (up to several hundred micrometers), to determine if the presence of myelination correlates with differences in cytoskeletal organization and neurofilament phosphorylation. Axonal caliber and neurofilament numbers were substantially greater in the myelinated internodes than in the stem process or nodes of Ranvier. Neurofilament spacing, assessed by measuring the nearest-neighbor neurofilament distance, was 25-50% less in the stem processes and nodes of Ranvier than in the myelinated internodes. In the myelinated internodes, neurofilaments had greater immunoreactivity for phosphorylated epitopes than those in the stem process. These findings indicate that interactions with Schwann cells modulate neurofilament phosphorylation within the ensheathed axonal segments, and that increased phosphorylation within myelinated internodes leads to greater interfilament spacing. Lastly, the myelinated internodes had three fold more neurofilaments, but the same number of microtubules. Both the increased neurofilament spacing and the increase in neurofilament numbers in myelinated internodes contribute to a greater axonal caliber in the myelinated internodes. |
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Authors:
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S T Hsieh; G J Kidd; T O Crawford; Z Xu; W M Lin; B D Trapp; D W Cleveland; J W Griffin |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Journal of neuroscience : the official journal of the Society for Neuroscience Volume: 14 ISSN: 0270-6474 ISO Abbreviation: J. Neurosci. Publication Date: 1994 Nov |
Date Detail:
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Created Date: 1994-12-06 Completed Date: 1994-12-06 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 8102140 Medline TA: J Neurosci Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 6392-401 Citation Subset: IM |
Affiliation:
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Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Axons / physiology*, ultrastructure Cytoskeleton / ultrastructure Ganglia, Spinal / cytology, physiology Myelin Sheath / physiology* Neurofilament Proteins / physiology*, ultrastructure Neurons, Afferent / physiology, ultrastructure Phosphorylation Rats Rats, Sprague-Dawley Reference Values |
| Grant Support | |
ID/Acronym/Agency:
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5T32 MH 18030/MH/NIMH NIH HHS; NS PO1-22849/NS/NINDS NIH HHS; R01-14784//PHS HHS |
| Chemical | |
Reg. No./Substance:
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0/Neurofilament Proteins |
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