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Comparison of Retinal Nerve Fiber Layer Thickness In Vivo and Axonal Transport after Chronic Intraocular Pressure Elevation in Young versus Older Rats

PURPOSE: To compare in young and old rats longitudinal measurements of retinal nerve fiber layer thickness (RNFLT) and axonal transport 3-weeks after chronic IOP elevation. METHOD: IOP was elevated unilaterally in 2- and 9.5-month-old Brown-Norway rats by intracameral injections of magnetic microbea...

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Autores principales: Abbott, Carla J., Choe, Tiffany E., Burgoyne, Claude F., Cull, Grant, Wang, Lin, Fortune, Brad
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4263742/
https://www.ncbi.nlm.nih.gov/pubmed/25501362
http://dx.doi.org/10.1371/journal.pone.0114546
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author Abbott, Carla J.
Choe, Tiffany E.
Burgoyne, Claude F.
Cull, Grant
Wang, Lin
Fortune, Brad
author_facet Abbott, Carla J.
Choe, Tiffany E.
Burgoyne, Claude F.
Cull, Grant
Wang, Lin
Fortune, Brad
author_sort Abbott, Carla J.
collection PubMed
description PURPOSE: To compare in young and old rats longitudinal measurements of retinal nerve fiber layer thickness (RNFLT) and axonal transport 3-weeks after chronic IOP elevation. METHOD: IOP was elevated unilaterally in 2- and 9.5-month-old Brown-Norway rats by intracameral injections of magnetic microbeads. RNFLT was measured by spectral domain optical coherence tomography. Anterograde axonal transport was assessed from confocal scanning laser ophthalmolscopy of superior colliculi (SC) after bilateral intravitreal injections of cholera toxin-B-488. Optic nerve sections were graded for damage. RESULTS: Mean IOP was elevated in both groups (young 37, old 38 mmHg, p = 0.95). RNFL in young rats exhibited 10% thickening at 1-week (50.9±8.1 µm, p<0.05) vs. baseline (46.4±2.4 µm), then 7% thinning at 2-weeks (43.0±7.2 µm, p>0.05) and 3-weeks (43.5±4.4 µm, p>0.05), representing 20% loss of dynamic range. RNFLT in old rats showed no significant change at 1-week (44.9±4.1 µm) vs. baseline (49.2±5.3 µm), but progression to 22% thinning at 2-weeks (38.0±3.7 µm, p<0.01) and 3-weeks (40.0±6.6 µm, p<0.05), representing 59% loss of dynamic range. Relative SC fluorescence intensity was reduced in both groups (p<0.001), representing 77–80% loss of dynamic range and a severe transport deficit. Optic nerves showed 75–95% damage (p<0.001). There was greater RNFL thinning in old rats (p<0.05), despite equivalent IOP insult, transport deficit and nerve damage between age groups (all p>0.05). CONCLUSION: Chronic IOP elevation resulted in severely disrupted axonal transport and optic nerve axon damage in all rats, associated with mild RNFL loss in young rats but a moderate RNFL loss in old rats despite the similar IOP insult. Hence, the glaucomatous injury response within the RNFL depends on age.
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spelling pubmed-42637422014-12-19 Comparison of Retinal Nerve Fiber Layer Thickness In Vivo and Axonal Transport after Chronic Intraocular Pressure Elevation in Young versus Older Rats Abbott, Carla J. Choe, Tiffany E. Burgoyne, Claude F. Cull, Grant Wang, Lin Fortune, Brad PLoS One Research Article PURPOSE: To compare in young and old rats longitudinal measurements of retinal nerve fiber layer thickness (RNFLT) and axonal transport 3-weeks after chronic IOP elevation. METHOD: IOP was elevated unilaterally in 2- and 9.5-month-old Brown-Norway rats by intracameral injections of magnetic microbeads. RNFLT was measured by spectral domain optical coherence tomography. Anterograde axonal transport was assessed from confocal scanning laser ophthalmolscopy of superior colliculi (SC) after bilateral intravitreal injections of cholera toxin-B-488. Optic nerve sections were graded for damage. RESULTS: Mean IOP was elevated in both groups (young 37, old 38 mmHg, p = 0.95). RNFL in young rats exhibited 10% thickening at 1-week (50.9±8.1 µm, p<0.05) vs. baseline (46.4±2.4 µm), then 7% thinning at 2-weeks (43.0±7.2 µm, p>0.05) and 3-weeks (43.5±4.4 µm, p>0.05), representing 20% loss of dynamic range. RNFLT in old rats showed no significant change at 1-week (44.9±4.1 µm) vs. baseline (49.2±5.3 µm), but progression to 22% thinning at 2-weeks (38.0±3.7 µm, p<0.01) and 3-weeks (40.0±6.6 µm, p<0.05), representing 59% loss of dynamic range. Relative SC fluorescence intensity was reduced in both groups (p<0.001), representing 77–80% loss of dynamic range and a severe transport deficit. Optic nerves showed 75–95% damage (p<0.001). There was greater RNFL thinning in old rats (p<0.05), despite equivalent IOP insult, transport deficit and nerve damage between age groups (all p>0.05). CONCLUSION: Chronic IOP elevation resulted in severely disrupted axonal transport and optic nerve axon damage in all rats, associated with mild RNFL loss in young rats but a moderate RNFL loss in old rats despite the similar IOP insult. Hence, the glaucomatous injury response within the RNFL depends on age. Public Library of Science 2014-12-11 /pmc/articles/PMC4263742/ /pubmed/25501362 http://dx.doi.org/10.1371/journal.pone.0114546 Text en © 2014 Abbott et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Abbott, Carla J.
Choe, Tiffany E.
Burgoyne, Claude F.
Cull, Grant
Wang, Lin
Fortune, Brad
Comparison of Retinal Nerve Fiber Layer Thickness In Vivo and Axonal Transport after Chronic Intraocular Pressure Elevation in Young versus Older Rats
title Comparison of Retinal Nerve Fiber Layer Thickness In Vivo and Axonal Transport after Chronic Intraocular Pressure Elevation in Young versus Older Rats
title_full Comparison of Retinal Nerve Fiber Layer Thickness In Vivo and Axonal Transport after Chronic Intraocular Pressure Elevation in Young versus Older Rats
title_fullStr Comparison of Retinal Nerve Fiber Layer Thickness In Vivo and Axonal Transport after Chronic Intraocular Pressure Elevation in Young versus Older Rats
title_full_unstemmed Comparison of Retinal Nerve Fiber Layer Thickness In Vivo and Axonal Transport after Chronic Intraocular Pressure Elevation in Young versus Older Rats
title_short Comparison of Retinal Nerve Fiber Layer Thickness In Vivo and Axonal Transport after Chronic Intraocular Pressure Elevation in Young versus Older Rats
title_sort comparison of retinal nerve fiber layer thickness in vivo and axonal transport after chronic intraocular pressure elevation in young versus older rats
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4263742/
https://www.ncbi.nlm.nih.gov/pubmed/25501362
http://dx.doi.org/10.1371/journal.pone.0114546
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