A novel in vivo model of focal light emitting diode-induced cone-photoreceptor phototoxicity: neuroprotection afforded by brimonidine, BDNF, PEDF or bFGF

PLoS One. 2014 Dec 2;9(12):e113798. doi: 10.1371/journal.pone.0113798. eCollection 2014.

Abstract

We have investigated the effects of light-emitting diode (LED)-induced phototoxicity (LIP) on cone-photoreceptors and their protection with brimonidine (BMD), brain-derived neurotrophic factor (BDNF), pigment epithelium-derived factor (PEDF), ciliary neurotrophic factor (CNTF) or basic fibroblast growth factor (bFGF). In anesthetized, dark adapted, adult albino rats a blue (400 nm) LED was placed perpendicular to the cornea (10 sec, 200 lux) and the effects were investigated using Spectral Domain Optical Coherence Tomography (SD-OCT) and/or analysing the retina in oriented cross-sections or wholemounts immune-labelled for L- and S-opsin and counterstained with the nuclear stain DAPI. The effects of topical BMD (1%) or, intravitreally injected BDNF (5 µg), PEDF (2 µg), CNTF (0.4 µg) or bFGF (1 µg) after LIP were examined on wholemounts at 7 days. SD-OCT showed damage in a circular region of the superotemporal retina, whose diameter varied from 1,842.4±84.5 µm (at 24 hours) to 1,407.7±52.8 µm (at 7 days). This region had a progressive thickness diminution from 183.4±5 µm (at 12 h) to 114.6±6 µm (at 7 d). Oriented cross-sections showed within the light-damaged region of the retina massive loss of rods and cone-photoreceptors. Wholemounts documented a circular region containing lower numbers of L- and S-cones. Within a circular area (1 mm or 1.3 mm radius, respectively) in the left and in its corresponding region of the contralateral-fellow-retina, total L- or S-cones were 7,118±842 or 661±125 for the LED exposed retinas (n = 7) and 14,040±1,860 or 2,255±193 for the fellow retinas (n = 7), respectively. BMD, BDNF, PEDF and bFGF but not CNTF showed significant neuroprotective effects on L- or S-cones. We conclude that LIP results in rod and cone-photoreceptor loss, and is a reliable, quantifiable model to study cone-photoreceptor degeneration. Intravitreal BDNF, PEDF or bFGF, or topical BMD afford significant cone neuroprotection in this model.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain-Derived Neurotrophic Factor / pharmacology*
  • Brimonidine Tartrate
  • Cell Survival / drug effects
  • Cell Survival / radiation effects
  • Disease Models, Animal
  • Electronics*
  • Eye Proteins / pharmacology*
  • Female
  • Fibroblast Growth Factor 2 / pharmacology*
  • Light / adverse effects*
  • Nerve Growth Factors / pharmacology*
  • Neuroprotective Agents / pharmacology*
  • Quinoxalines / pharmacology*
  • Rats, Sprague-Dawley
  • Retinal Cone Photoreceptor Cells / drug effects
  • Retinal Cone Photoreceptor Cells / pathology*
  • Retinal Cone Photoreceptor Cells / radiation effects*
  • Serpins / pharmacology*
  • Time Factors
  • Tomography, Optical Coherence

Substances

  • Brain-Derived Neurotrophic Factor
  • Eye Proteins
  • Nerve Growth Factors
  • Neuroprotective Agents
  • Quinoxalines
  • Serpins
  • pigment epithelium-derived factor
  • Fibroblast Growth Factor 2
  • Brimonidine Tartrate