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Brimonidine prevents axonal and somatic degeneration of retinal ganglion cell neurons

BACKGROUND: Brimonidine is a common drug for lowering ocular pressure and may directly protect retinal ganglion cells in glaucoma. The disease involves early loss of retinal ganglion cell transport to brain targets followed by axonal and somatic degeneration. We examined whether brimonidine preserve...

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Autores principales: Lambert, Wendi S, Ruiz, Lupe, Crish, Samuel D, Wheeler, Larry A, Calkins, David J
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035592/
https://www.ncbi.nlm.nih.gov/pubmed/21232114
http://dx.doi.org/10.1186/1750-1326-6-4
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author Lambert, Wendi S
Ruiz, Lupe
Crish, Samuel D
Wheeler, Larry A
Calkins, David J
author_facet Lambert, Wendi S
Ruiz, Lupe
Crish, Samuel D
Wheeler, Larry A
Calkins, David J
author_sort Lambert, Wendi S
collection PubMed
description BACKGROUND: Brimonidine is a common drug for lowering ocular pressure and may directly protect retinal ganglion cells in glaucoma. The disease involves early loss of retinal ganglion cell transport to brain targets followed by axonal and somatic degeneration. We examined whether brimonidine preserves ganglion cell axonal transport and abates degeneration in rats with elevated ocular pressure induced by laser cauterization of the episcleral veins. RESULTS: Ocular pressure was elevated unilaterally by 90% for a period of 8 weeks post- cauterization. During this time, brimonidine (1mg/kg/day) or vehicle (phosphate-buffered saline) was delivered systemically and continuously via subcutaneous pump. Animals received bilateral intravitreal injections of fluorescent cholera toxin subunit β (CTB) two days before sacrifice to assess anterograde transport. In retinas from the vehicle group, elevated pressure induced a 44% decrease in the fraction of ganglion cells with intact uptake of CTB and a 14-42% reduction in the number of immuno-labelled ganglion cell bodies, with the worst loss occurring nasally. Elevated pressure also caused a 33% loss of ganglion cell axons in vehicle optic nerves and a 70% decrease in CTB transport to the superior colliculus. Each of these components of ganglion cell degeneration was either prevented or significantly reduced in the brimonidine treatment group. CONCLUSIONS: Continuous and systemic treatment with brimonidine by subcutaneous injection significantly improved retinal ganglion cell survival with exposure to elevated ocular pressure. This effect was most striking in the nasal region of the retina. Brimonidine treatment also preserved ganglion cell axon morphology, sampling density and total number in the optic nerve with elevated pressure. Consistent with improved outcome in the optic projection, brimonidine also significantly reduced the deficits in axonal transport to the superior colliculus associated with elevated ocular pressure. As transport deficits to and from retinal ganglion cell projection targets in the brain are relevant to the progression of glaucoma, the ability of brimonidine to preserve optic nerve axons and active transport suggests its neuroprotective effects are relevant not only at the cell body, but throughout the entire optic projection.
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spelling pubmed-30355922011-02-09 Brimonidine prevents axonal and somatic degeneration of retinal ganglion cell neurons Lambert, Wendi S Ruiz, Lupe Crish, Samuel D Wheeler, Larry A Calkins, David J Mol Neurodegener Research Article BACKGROUND: Brimonidine is a common drug for lowering ocular pressure and may directly protect retinal ganglion cells in glaucoma. The disease involves early loss of retinal ganglion cell transport to brain targets followed by axonal and somatic degeneration. We examined whether brimonidine preserves ganglion cell axonal transport and abates degeneration in rats with elevated ocular pressure induced by laser cauterization of the episcleral veins. RESULTS: Ocular pressure was elevated unilaterally by 90% for a period of 8 weeks post- cauterization. During this time, brimonidine (1mg/kg/day) or vehicle (phosphate-buffered saline) was delivered systemically and continuously via subcutaneous pump. Animals received bilateral intravitreal injections of fluorescent cholera toxin subunit β (CTB) two days before sacrifice to assess anterograde transport. In retinas from the vehicle group, elevated pressure induced a 44% decrease in the fraction of ganglion cells with intact uptake of CTB and a 14-42% reduction in the number of immuno-labelled ganglion cell bodies, with the worst loss occurring nasally. Elevated pressure also caused a 33% loss of ganglion cell axons in vehicle optic nerves and a 70% decrease in CTB transport to the superior colliculus. Each of these components of ganglion cell degeneration was either prevented or significantly reduced in the brimonidine treatment group. CONCLUSIONS: Continuous and systemic treatment with brimonidine by subcutaneous injection significantly improved retinal ganglion cell survival with exposure to elevated ocular pressure. This effect was most striking in the nasal region of the retina. Brimonidine treatment also preserved ganglion cell axon morphology, sampling density and total number in the optic nerve with elevated pressure. Consistent with improved outcome in the optic projection, brimonidine also significantly reduced the deficits in axonal transport to the superior colliculus associated with elevated ocular pressure. As transport deficits to and from retinal ganglion cell projection targets in the brain are relevant to the progression of glaucoma, the ability of brimonidine to preserve optic nerve axons and active transport suggests its neuroprotective effects are relevant not only at the cell body, but throughout the entire optic projection. BioMed Central 2011-01-13 /pmc/articles/PMC3035592/ /pubmed/21232114 http://dx.doi.org/10.1186/1750-1326-6-4 Text en Copyright ©2011 Lambert et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Article
Lambert, Wendi S
Ruiz, Lupe
Crish, Samuel D
Wheeler, Larry A
Calkins, David J
Brimonidine prevents axonal and somatic degeneration of retinal ganglion cell neurons
title Brimonidine prevents axonal and somatic degeneration of retinal ganglion cell neurons
title_full Brimonidine prevents axonal and somatic degeneration of retinal ganglion cell neurons
title_fullStr Brimonidine prevents axonal and somatic degeneration of retinal ganglion cell neurons
title_full_unstemmed Brimonidine prevents axonal and somatic degeneration of retinal ganglion cell neurons
title_short Brimonidine prevents axonal and somatic degeneration of retinal ganglion cell neurons
title_sort brimonidine prevents axonal and somatic degeneration of retinal ganglion cell neurons
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035592/
https://www.ncbi.nlm.nih.gov/pubmed/21232114
http://dx.doi.org/10.1186/1750-1326-6-4
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