June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Altered astrocyte morphology and intermediate filament distribution in the rat optic nerve following acoustic blast overpressure exposure
Author Affiliations & Notes
  • Lara Ann Skelton
    Research Service, VA Western NY Healthcare System, Buffalo, NY, United States, Buffalo, New York, United States
    Ophthalmology, Biochemistry, and Neuroscience Graduate Program, University at Buffalo, Buffalo, New York, United States
  • Sriganesh Ramachandra Rao
    Research Service, VA Western NY Healthcare System, Buffalo, NY, United States, Buffalo, New York, United States
    Ophthalmology, Biochemistry, and Neuroscience Graduate Program, University at Buffalo, Buffalo, New York, United States
  • Machelle T Pardue
    Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, Georgia, United States
    Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
  • Steven J Fliesler
    Research Service, VA Western NY Healthcare System, Buffalo, NY, United States, Buffalo, New York, United States
    Ophthalmology, Biochemistry, and Neuroscience Graduate Program, University at Buffalo, Buffalo, New York, United States
  • Footnotes
    Commercial Relationships   Lara Skelton None; Sriganesh Ramachandra Rao None; Machelle Pardue None; Steven Fliesler None
  • Footnotes
    Support  VA MERIT Award 1I0 BX002439 (SJF, MTP), Research Career Scientist Awards (SJF, MTP); VA facilities and resources (SJF, MTP)
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 986 – F0383. doi:
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    • Get Citation

      Lara Ann Skelton, Sriganesh Ramachandra Rao, Machelle T Pardue, Steven J Fliesler; Altered astrocyte morphology and intermediate filament distribution in the rat optic nerve following acoustic blast overpressure exposure. Invest. Ophthalmol. Vis. Sci. 2022;63(7):986 – F0383.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Glial and neuronal responses to acoustic blast overpressure (ABO) exposure have been studied extensively in the brain and retina, but remain relatively uncharacterized in the optic nerve. We examined the expression and distribution patterns of GFAP, synemin, nestin and neurofilament-M (NF-M) in rat optic nerve following ABO relative to unexposed controls, to ascertain basal and post-blast distribution of these major intermediate filament (IF) cytoskeletal components.

Methods : Anesthetized adult male Long-Evans rats were subjected to ABO exposure, with the blast directed at the right side of the head (Allen et al., 2018, 2021). Optic nerves were harvested at 1 wk post-ABO alongside non-exposed, age/sex-matched controls, and fixed in PBS-buffered PFA. Transverse cryosections (O.C.T. embedment) were prepared, subjected to antigen retrieval, and processed for confocal microscopy immunofluorescence histochemistry (IHC) using polyclonal antibodies (Abs) against GFAP, nestin, and NF-M, and monoclonal antibodies against synemin (clone A8), with suitable fluor-conjugated secondary Abs. Local thickness mapping and particle analysis of synemin immunolabeling through z-stacks was performed in FIJI ImageJ™. Statistical analysis: Student’s t-test, significance threshold p<0.05 (N=3/group).

Results : GFAP, nestin and synemin were robustly expressed in control optic nerve astrocytes, with overlapping distribution through the IF cytoskeleton. Astrocytes were evenly distributed through control transverse optic nerve sections. Synemin partially co-localized with GFAP and nestin IF and appeared to form fine cytoskeletal structures along the astrocytic cell processes. At 1 wk post-ABO, astrocytes appeared heterogeneous, with a sub-population exhibiting hypertrophic cell processes, and were re-distributed more centrally in the optic nerve. Co-labeling for axons using anti-NF-M identified distinct axonal bundles that appeared ordered and regularly spaced in control optic nerves. At 1 wk post-ABO, peripheral disturbance to the axon bundles was observed. Local thickness analysis revealed a ~1.5-fold increase in particle size of cytoskeletal synemin through the astrocytic processes.

Conclusions : Astrocytes undergo morphological and distribution changes in the rat optic nerve following ABO, accompanied by altered synemin localization through the IF cytoskeleton.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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