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Abstract #84559 Published in IGR 21-1
Elevated ocular pressure reduces voltage-gated sodium channel NaV1.2 protein expression in retinal ganglion cell axons
Risner ML; McGrady NR; Pasini S; Lambert WS; Calkins DJExperimental Eye Research 2020; 190: 107873
Glaucoma is an age-related neurodegenerative disease that is commonly associated with sensitivity to intraocular pressure. The disease selectively targets retinal ganglion cells (RGCs) and constituent axons. RGC axons are rich in voltage-gated sodium channels, which are essential for action potential initiation and regeneration. Here, we identified voltage-dependent sodium channel, NaV1.2, in the retina, examined how this channel contributes to RGC light responses, and monitored NaV1.2 mRNA and protein expression in the retina during progression of modeled glaucoma. We found NaV1.2 is predominately localized in ganglion cell intraretinal axons with dispersed expression in the outer and inner plexiform layers. We showed Phrixotoxin-3, a potent NaV1.2 channel blocker, significantly decreased RGC electrical activity in a dose-dependent manner with an I50 of 40 nM. Finally, we found four weeks of raised intraocular pressure (30% above baseline) significantly increased NaV1.2 mRNA expression but reduced NaV1.2 protein level in the retina up to 57% (p < 0.001). Following prolonged intraocular pressure elevation, NaV1.2 protein expression particularly diminished at distal sections of ganglion cell intraretinal axons (p ≤ 0.01). Our results suggest NaV1.2 might be a therapeutic target during disease progression to maintain RGC excitability, preserving presynaptic connections through action potential backpropagation.
Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 11435 Medical Research Building IV, 2215B Garland Ave, Nashville, TN, 37232-0654, USA.
Full articleClassification:
3.6 Cellular biology (Part of: 3 Laboratory methods)
3.5 Molecular biology incl. SiRNA (Part of: 3 Laboratory methods)
11.8 Neuroprotection (Part of: 11 Medical treatment)
