Document Detail


Effects of acutely elevated hydrostatic pressure in a rat ex vivo retinal preparation.
MedLine Citation:
PMID:  20688725     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: A new experimental glaucoma model was developed by using an ex vivo rat retinal preparation to examine the effects of elevated hydrostatic pressure on retinal morphology and glutamine synthetase (GS) activity.
METHODS: Ex vivo rat retinas were exposed to elevated hydrostatic pressure for 24 hours in the presence of glutamate or glutamate receptor antagonists and examined histologically. GS activity was assessed by colorimetric assay.
RESULTS: Pressure elevation induced axonal swelling in the nerve fiber layer. Axonal swelling was prevented by a combination of non-N-methyl-d-aspartate (non-NMDA) receptor antagonist and an NMDA receptor antagonist, indicating that the damage results from activation of both types of glutamate receptor. When glial function was preserved, the typical changes induced by glutamate consisted of reversible Müller cell swelling resulting from excessive glial glutamate uptake. The irreversible Müller cell swelling in hyperbaric conditions may indicate that pressure disrupts glutamate metabolism. Indeed, elevated pressure inhibited GS activity. In addition, glutamate exposure after termination of pressure exposure exhibited apparent Müller cell swelling.
CONCLUSIONS: These results suggest that the neural degeneration observed during pressure elevation is caused by impaired glial glutamate metabolism after uptake.
Authors:
Makoto Ishikawa; Takeshi Yoshitomi; Charles F Zorumski; Yukitoshi Izumi
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-08-04
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  51     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-02     Completed Date:  2011-01-13     Revised Date:  2013-05-29    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  6414-23     Citation Subset:  IM    
Affiliation:
Department of Ophthalmology, Akita University School of Medicine, Akita, Japan. mako@med.akita-u.ac.jp
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MeSH Terms
Descriptor/Qualifier:
Animals
Axons / metabolism*,  ultrastructure
Disease Models, Animal*
Dizocilpine Maleate / pharmacology
Excitatory Amino Acid Antagonists / pharmacology
Fluorescent Antibody Technique, Indirect
Glial Fibrillary Acidic Protein / metabolism
Glutamate-Ammonia Ligase / metabolism
Glutamic Acid / metabolism*
Hydrostatic Pressure
Male
Optic Disk / metabolism,  ultrastructure
Optic Nerve Diseases / etiology,  metabolism*,  pathology
Rats
Rats, Sprague-Dawley
Receptors, Glutamate / metabolism
Retinal Diseases / etiology,  metabolism*,  pathology
Retinal Ganglion Cells / metabolism*,  ultrastructure
Grant Support
ID/Acronym/Agency:
MH077791/MH/NIMH NIH HHS; NS57105/NS/NINDS NIH HHS
Chemical
Reg. No./Substance:
0/Excitatory Amino Acid Antagonists; 0/Glial Fibrillary Acidic Protein; 0/Receptors, Glutamate; 56-86-0/Glutamic Acid; 77086-22-7/Dizocilpine Maleate; EC 6.3.1.2/Glutamate-Ammonia Ligase
Comments/Corrections

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