Melanopsin+RGCs Are fully Resistant to NMDA-Induced Excitotoxicity.
We studied short- and long-term effects of intravitreal injection of N-methyl-d-aspartate (NMDA) on melanopsin-containing (m+) and non-melanopsin-containing (Brn3a+) retinal ganglion cells (RGCs). In adult SD-rats, the left eye received a single intravitreal injection of 5µL of 100nM NMDA. At 3 and 15 months, retinal thickness was measured in vivo using Spectral Domain-Optical Coherence Tomography (SD-OCT). Ex vivo analyses were done at 3, 7, or 14 days or 15 months after damage. Whole-mounted retinas were immunolabelled for brain-specific homeobox/POU domain protein 3A (Brn3a) and melanopsin (m), the total number of Brn3a+RGCs and m+RGCs were quantified, and their topography represented. In control retinas, the mean total numbers of Brn3a+RGCs and m+RGCs were 78,903 ± 3572 and 2358 ± 144 (mean ± SD; n = 10), respectively. In the NMDA injected retinas, Brn3a+RGCs numbers diminished to 49%, 28%, 24%, and 19%, at 3, 7, 14 days, and 15 months, respectively. There was no further loss between 7 days and 15 months. The number of immunoidentified m+RGCs decreased significantly at 3 days, recovered between 3 and 7 days, and were back to normal thereafter. OCT measurements revealed a significant thinning of the left retinas at 3 and 15 months. Intravitreal injections of NMDA induced within a week a rapid loss of 72% of Brn3a+RGCs, a transient downregulation of melanopsin expression (but not m+RGC death), and a thinning of the inner retinal layers.
['Vidal-Villegas|Beatriz|B|', 'Di Pierdomenico|Johnny|J|0000-0001-9124-9247', 'Miralles de Imperial-Ollero|Juan A|JA|', 'Ortín-Martínez|Arturo|A|', 'Nadal-Nicolás|Francisco M|FM|0000-0003-4121-514X', 'Bernal-Garro|Jose M|JM|', 'Cuenca Navarro|Nicolás|N|', 'Villegas-Pérez|María P|MP|', 'Vidal-Sanz|Manuel|M|']
D000818:Animals D002452:Cell Count D005260:Female D058449:Intravitreal Injections D016202:N-Methylaspartate D017207:Rats, Sprague-Dawley D016194:Receptors, N-Methyl-D-Aspartate D012165:Retinal Ganglion Cells D017299:Rod Opsins D050819:Transcription Factor Brn-3A
excitotoxicity NMDA SD-OCT retina Brn3a+RGCs adult albino rat glaucoma intrinsically photosensitive-RGCs melanopsin-RGCs