June 2020
Volume 61, Issue 7
ARVO Annual Meeting Abstract  |   June 2020
Chronic trans-scleral electrical stimulation by an implanted microstimulator for the survival of axotomized retinal ganglion cells in adult rats
Author Affiliations & Notes
  • Takeshi Morimoto
    Advanced visual neuroscience, Osaka University graduate school of medicine, Japan
  • Takashi Fujikado
    Osaka University Graduate School of Frontier Biosciences, Japan
  • Tomomitsu Miyoshi
    Integrative Physiology, Osaka University graduate school of medicine, Japan
  • Kohji Nishida
    4. Department of Ophthalmology, Osaka university graduate school of medicine, Japan
    Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Japan
  • Footnotes
    Commercial Relationships   Takeshi Morimoto, None; Takashi Fujikado, None; Tomomitsu Miyoshi, None; Kohji Nishida, None
  • Footnotes
    Support  KAKEN 19K09969
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 2198. doi:
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      Takeshi Morimoto, Takashi Fujikado, Tomomitsu Miyoshi, Kohji Nishida; Chronic trans-scleral electrical stimulation by an implanted microstimulator for the survival of axotomized retinal ganglion cells in adult rats. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2198.

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

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Purpose : Previously we demonstrated that transient transcorneal electrical stimulation is neuroprotective for retinal neurons in vivo. Therefore it is possible that chronic electrical stimulation by an implantable device such as a retinal prosthesis exerts neuroprotection. In this study we investigated the effect of chronic trans-scleral electrical stimulation (ES) on the survival of axotomized retinal ganglion cells (RGCs) in vivo.

Methods : Adult Long-Evans rats were used. The left optic nerve (ON) was transected 3 mm from the posterior eye pole. Subsequently, a small sponge soaked in 2% Fluorogold (FG), a fluorescent tracer for retrograde labeling of RGCs was placed on the ON stump.
Ring electrodes with a diameter of 1.5 mm were sutured onto the sclera at the upper equator of the eye. The electrodes were connected to an implantable pulse generator unit (ISE1000SA; UNIMEC,Tokyo, Japan). The electrical stimuli consisted of 20 Hz, anodic first biphasic rectangular current pulses (50 µA, 1ms/phase ) that were delivered from the generator for a week. Seven days after ON transection, Only the left (transected) eye was enucleated, then the retinas were flat-mounted. The surviving FG-labeled RGCs were counted in 12 areas covering the whole retina under a fluorescent microscope, and the densities of RGCs were determined. The density of RGCs in the retina one day after ON cut was set as a control. In sham stimulation group, electrodes were sutured, but were not connected to the generator.

Results : Seven days after ON transection with sham stimulation, the mean RGC density (1246±142 cells/mm2 (mean ± SD), n = 8) significantly decreased to 52.1 % of control retinas (2390±194 cells/mm2, n = 8). ES exerted the neuroprotective effect on injured RGCs. the mean RGC densities were 86.7% of control value (2073±149 cells/mm2 , n = 8 ; P < 0.001 vs sham).

Conclusions : Chronic ES promotes the survival of axotomized RGCs in adult rats. These results propose the beneficial information for the clinical application of chronic ES such as retinal prosthesis to prevent or delay the degeneration of retinal neurons.

This is a 2020 ARVO Annual Meeting abstract.


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