Document Detail

Ultrastructural analysis of the paranodal junction of myelinated fibers in 31-month-old-rats.
MedLine Citation:
PMID:  12391590     Owner:  NLM     Status:  MEDLINE    
Recent studies have revealed a significant decrease in white matter volume, including loss of myelin, with age but minimal decrease in gray matter volume (Guttmann et al., [1998] Neurology 50:972-978). Myelin is necessary for the rapid conduction of impulses along axons. Myelinated nerve includes various domains, the node of Ranvier, the paranodal region, the juxtaparanodal region and the internode. The paranodal junction may serve to anchor the myelin sheath to the axon. We analyzed the ultrastructure of the paranodal region in myelinated fibers from the aged rat brain. Severe alterations of myelinated fibers were observed in 31-month-old rats, resulting in the appearance of macrophages, splitting of the myelin sheath, myelin balloon formation and separation from the axon. Many paranodal retractions of myelinated axons occurred in the aged rats. It should be noted that the paranodal junction is functionally important, serving to anchor the myelin to the axon and that there is a diffusion barrier in the paranodal region. We analyzed myelin-related proteins from young and aged rat brains. The 21.5-kDa isoform of myelin basic protein (MBP) almost disappeared in the 31-month-old rats, whereas other myelin proteins were not significantly changed between young and aged rats. These results suggest that this isoform, a highly cationic charged major dense component protein that binds lipid bilayer in the membrane, may participate in the formation of a paranodal diffusion barrier at the myelin/noncompact membrane border.
Ichiro Sugiyama; Kayoko Tanaka; Masumi Akita; Kazunari Yoshida; Takeshi Kawase; Hiroaki Asou
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of neuroscience research     Volume:  70     ISSN:  0360-4012     ISO Abbreviation:  J. Neurosci. Res.     Publication Date:  2002 Nov 
Date Detail:
Created Date:  2002-10-22     Completed Date:  2002-12-13     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  7600111     Medline TA:  J Neurosci Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  309-17     Citation Subset:  IM    
Copyright Information:
Copyright 2002 Wiley-Liss, Inc.
Department of Neurobiology, Tokyo Metropolitan Institute of Gerontology, Itabashiku, Tokyo, Japan.
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MeSH Terms
Aging / pathology*
Animals, Newborn
Axons / pathology,  ultrastructure
Brain / pathology*,  physiopathology
Cell Adhesion Molecules, Neuron-Glia / analysis
Macrophages / pathology,  ultrastructure
Microscopy, Electron
Myelin Proteins / analysis
Nerve Fibers, Myelinated / pathology*,  ultrastructure
Neural Conduction / physiology
Ranvier's Nodes / pathology*,  ultrastructure
Rats, Inbred F344
Reg. No./Substance:
0/Cell Adhesion Molecules, Neuron-Glia; 0/Myelin Proteins

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