September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Degeneration of postsynaptic terminals, but not second-order neurons following light-induced photoreceptor degeneration
Author Affiliations & Notes
  • Mohajeet Balveer Bhuckory
    Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom
  • Aisling Lynch
    Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom
  • Mei Chen
    Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom
  • Heping Xu
    Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom
  • Footnotes
    Commercial Relationships   Mohajeet Bhuckory, None; Aisling Lynch, None; Mei Chen, None; Heping Xu, None
  • Footnotes
    Support  Fight for sight Grant1425/426
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 2746. doi:
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      Mohajeet Balveer Bhuckory, Aisling Lynch, Mei Chen, Heping Xu; Degeneration of postsynaptic terminals, but not second-order neurons following light-induced photoreceptor degeneration. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2746.

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      © 2017 Association for Research in Vision and Ophthalmology.

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Abstract

Purpose : Photoreceptor degeneration underlies many sight-threatening diseases, including retinitis pigmentosa (PR) and age-related macular degeneration (AMD). Photoreceptors are connected with second-order neurons such as rod-/cone-bipolar cells and horizontal cells. How the second order neurons remodel after the death of photoreceptor is not fully understood, although the knowledge is important for developing photoreceptor regeneration therapies. The aim of this study was to investigate the dynamic remodel process of retinal neurons in a mouse model of focal light-induced photoreceptor degeneration.

Methods : Adult C57BL/6J mice were dark adapted for 48 hours prior to light exposure. Pupils were dilated and eyes were exposed to 90,000 lux of cold light for 10mins using an otoscope (1218AA, Karl Storz, Tuttlingen, Germany). Retinal lesions were examined by fundus images and Spectral Domain Optical Coherence Tomography (SD-OCT). The mice were culled and eyes enucleated on day 4 and day 11 post-light exposure for processing by Immunohistochemistry. Retinal sections were stained with cone arrestin, rhodopsin, PKCα, secretagogin, GABA,GlyT1, calbindin, synaptophysin, glutamate synthase, GFAP and Brn3a.

Results : Focal light exposure induced rapid (within 4 days) localized total degeneration of photoreceptors in the fundus, and the lesion size ranges from 500-1800 μm. Immunohistochemistry showed that the number of PKCα+ bipolar cells did not change in the lesion area compared to non-damaged area and to non-light exposed eyes. However, postsynaptic terminals at the outer plexiform layer were severely degenerated at day 4 and 11. Synaptophysin staining showed that there was a significant decrease in the synaptic connections (p<0.0001). The number of amacrine and ganglion cells in the photoreceptor damaged area did not change significantly compared to controls. The PKCα and secretagogin synaptic connectivity at the IPL showed a non significant decrease in light-damaged area.

Conclusions : Our results suggest that photoreceptor death induces the degeneration of postsynaptic terminals but does not cause significant cell death in second order neurons in at least up to 11 days after light damage. Further study will need to address how long the second order neurons can remain stable following photoreceptor death.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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