Astrocyte processes label for filamentous actin and reorient early within the optic nerve head in a rat glaucoma model

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Abstract

PURPOSE: To determine if astrocyte processes label for actin and to quantify the orientation of astrocytic processes within the optic nerve head (ONH) in a rat glaucoma model.

METHODS: Chronic intraocular pressure (IOP) elevation was produced by episcleral hypertonic saline injection and tissues were collected after 5 weeks. For comparison, eyes with optic nerve transection were collected at 2 weeks. Fellow eyes served as controls. Axonal degeneration in retrobulbar optic nerves was graded on a scale of 1 to 5. Optic nerve head sections (n ≥ 4 eyes per group) were colabeled with phalloidin (actin marker) and antibodies to astrocytic glial fibrillary acidic protein and aquaporin 4, or axonal tubulin βIII. Confocal microscopy and FIJI software were used to quantify the orientation of actin bundles.

RESULTS: Control ONHs showed stereotypically arranged actin bundles within astrocyte processes. Optic nerve head actin bundle orientation was nearly perpendicular to axons (82.9° ± 6.3° relative to axonal axis), unlike the retrobulbar optic nerve (45.4° ± 28.7°, P <0.05). With IOP elevation, ONH actin bundle orientation became less perpendicular to axons, even in eyes with no perceivable axonal injury (i.e., 38.8° ± 15.1° in grade 1, P <0.05 in comparison to control ONHs). With severe injury, ONH actin bundle orientation became more parallel to the axonal axis (24.1° ± 28.4°, P <0.05 in comparison to control ONHs). Optic nerve head actin bundle orientation in transected optic nerves was unchanged.

CONCLUSIONS: Actin labeling identifies fine astrocyte processes within the ONH. Optic nerve head astrocyte process reorientation occurs early in response to elevated IOP.

Original languageEnglish (US)
Pages (from-to)6945-6952
Number of pages8
JournalInvestigative Ophthalmology and Visual Science
Volume55
Issue number10
DOIs
StatePublished - Oct 1 2014

Fingerprint

Optic Disk
Astrocytes
Glaucoma
Actins
Optic Nerve
Intraocular Pressure
Axons
Aquaporin 4
Optic Nerve Injuries
Phalloidine
Glial Fibrillary Acidic Protein
Wounds and Injuries
Tubulin
Confocal Microscopy
Software
Injections
Antibodies

Keywords

  • actin
  • astrocyte
  • glaucoma
  • intraocular pressure
  • optic nerve head

ASJC Scopus subject areas

  • Medicine(all)

Cite this

@article{74f1543c3bf64b4bae7e4e201191fcca,
title = "Astrocyte processes label for filamentous actin and reorient early within the optic nerve head in a rat glaucoma model",
abstract = "PURPOSE: To determine if astrocyte processes label for actin and to quantify the orientation of astrocytic processes within the optic nerve head (ONH) in a rat glaucoma model.METHODS: Chronic intraocular pressure (IOP) elevation was produced by episcleral hypertonic saline injection and tissues were collected after 5 weeks. For comparison, eyes with optic nerve transection were collected at 2 weeks. Fellow eyes served as controls. Axonal degeneration in retrobulbar optic nerves was graded on a scale of 1 to 5. Optic nerve head sections (n ≥ 4 eyes per group) were colabeled with phalloidin (actin marker) and antibodies to astrocytic glial fibrillary acidic protein and aquaporin 4, or axonal tubulin βIII. Confocal microscopy and FIJI software were used to quantify the orientation of actin bundles.RESULTS: Control ONHs showed stereotypically arranged actin bundles within astrocyte processes. Optic nerve head actin bundle orientation was nearly perpendicular to axons (82.9° ± 6.3° relative to axonal axis), unlike the retrobulbar optic nerve (45.4° ± 28.7°, P <0.05). With IOP elevation, ONH actin bundle orientation became less perpendicular to axons, even in eyes with no perceivable axonal injury (i.e., 38.8° ± 15.1° in grade 1, P <0.05 in comparison to control ONHs). With severe injury, ONH actin bundle orientation became more parallel to the axonal axis (24.1° ± 28.4°, P <0.05 in comparison to control ONHs). Optic nerve head actin bundle orientation in transected optic nerves was unchanged.CONCLUSIONS: Actin labeling identifies fine astrocyte processes within the ONH. Optic nerve head astrocyte process reorientation occurs early in response to elevated IOP.",
keywords = "actin, astrocyte, glaucoma, intraocular pressure, optic nerve head",
author = "Shandiz Tehrani and Elaine Johnson and Cepurna, {William O.} and John Morrison",
year = "2014",
month = "10",
day = "1",
doi = "10.1167/iovs.14-14969",
language = "English (US)",
volume = "55",
pages = "6945--6952",
journal = "Investigative Ophthalmology and Visual Science",
issn = "0146-0404",
publisher = "Association for Research in Vision and Ophthalmology Inc.",
number = "10",

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TY - JOUR

T1 - Astrocyte processes label for filamentous actin and reorient early within the optic nerve head in a rat glaucoma model

AU - Tehrani, Shandiz

AU - Johnson, Elaine

AU - Cepurna, William O.

AU - Morrison, John

PY - 2014/10/1

Y1 - 2014/10/1

N2 - PURPOSE: To determine if astrocyte processes label for actin and to quantify the orientation of astrocytic processes within the optic nerve head (ONH) in a rat glaucoma model.METHODS: Chronic intraocular pressure (IOP) elevation was produced by episcleral hypertonic saline injection and tissues were collected after 5 weeks. For comparison, eyes with optic nerve transection were collected at 2 weeks. Fellow eyes served as controls. Axonal degeneration in retrobulbar optic nerves was graded on a scale of 1 to 5. Optic nerve head sections (n ≥ 4 eyes per group) were colabeled with phalloidin (actin marker) and antibodies to astrocytic glial fibrillary acidic protein and aquaporin 4, or axonal tubulin βIII. Confocal microscopy and FIJI software were used to quantify the orientation of actin bundles.RESULTS: Control ONHs showed stereotypically arranged actin bundles within astrocyte processes. Optic nerve head actin bundle orientation was nearly perpendicular to axons (82.9° ± 6.3° relative to axonal axis), unlike the retrobulbar optic nerve (45.4° ± 28.7°, P <0.05). With IOP elevation, ONH actin bundle orientation became less perpendicular to axons, even in eyes with no perceivable axonal injury (i.e., 38.8° ± 15.1° in grade 1, P <0.05 in comparison to control ONHs). With severe injury, ONH actin bundle orientation became more parallel to the axonal axis (24.1° ± 28.4°, P <0.05 in comparison to control ONHs). Optic nerve head actin bundle orientation in transected optic nerves was unchanged.CONCLUSIONS: Actin labeling identifies fine astrocyte processes within the ONH. Optic nerve head astrocyte process reorientation occurs early in response to elevated IOP.

AB - PURPOSE: To determine if astrocyte processes label for actin and to quantify the orientation of astrocytic processes within the optic nerve head (ONH) in a rat glaucoma model.METHODS: Chronic intraocular pressure (IOP) elevation was produced by episcleral hypertonic saline injection and tissues were collected after 5 weeks. For comparison, eyes with optic nerve transection were collected at 2 weeks. Fellow eyes served as controls. Axonal degeneration in retrobulbar optic nerves was graded on a scale of 1 to 5. Optic nerve head sections (n ≥ 4 eyes per group) were colabeled with phalloidin (actin marker) and antibodies to astrocytic glial fibrillary acidic protein and aquaporin 4, or axonal tubulin βIII. Confocal microscopy and FIJI software were used to quantify the orientation of actin bundles.RESULTS: Control ONHs showed stereotypically arranged actin bundles within astrocyte processes. Optic nerve head actin bundle orientation was nearly perpendicular to axons (82.9° ± 6.3° relative to axonal axis), unlike the retrobulbar optic nerve (45.4° ± 28.7°, P <0.05). With IOP elevation, ONH actin bundle orientation became less perpendicular to axons, even in eyes with no perceivable axonal injury (i.e., 38.8° ± 15.1° in grade 1, P <0.05 in comparison to control ONHs). With severe injury, ONH actin bundle orientation became more parallel to the axonal axis (24.1° ± 28.4°, P <0.05 in comparison to control ONHs). Optic nerve head actin bundle orientation in transected optic nerves was unchanged.CONCLUSIONS: Actin labeling identifies fine astrocyte processes within the ONH. Optic nerve head astrocyte process reorientation occurs early in response to elevated IOP.

KW - actin

KW - astrocyte

KW - glaucoma

KW - intraocular pressure

KW - optic nerve head

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