Laser-induced ocular hypertension in adult rats does not affect non-RGC neurons in the ganglion cell layer but results in protracted severe loss of cone-photoreceptors.

Abstract

To investigate the long-term effects of laser-photocoagulation (LP)-induced ocular hypertension (OHT) in the innermost and outermost (outer-nuclear and outer segment)-retinal layers (ORL). OHT was induced in the left eye of adult rats. To investigate the ganglion cell layer (GCL) wholemounts were examined at 1, 3 or 6 months using Brn3a-immunodetection to identify retinal ganglion cells (RGCs) and DAPI-staining to detect all nuclei in this layer. To study the effects of LP on the ORL up to 6 months, retinas were: i) fresh extracted to quantify the levels of rod-, S- and L-opsin; ii) cut in cross-sections for morphometric analysis, or; iii) prepared as wholemounts to quantify and study retinal distributions of entire populations of RGCs (retrogradely labeled with fluorogold, FG), S- and L-cones (immunolabeled). OHT resulted in wedge-like sectors with their apex on the optic disc devoid of Brn3a(+)RGCs but with large numbers of DAPI(+)nuclei. The levels of all opsins diminished by 2 weeks and further decreased to 20% of basal-levels by 3 months. Cross-sections revealed focal areas of ORL degeneration. RGC survival at 15 days represented approximately 28% and did not change with time, whereas the S- and L-cone populations diminished to 65% and 80%, or to 20 and 35% at 1 or 6 months, respectively. In conclusion, LP induces in the GCL selective RGCs loss that does not progress after 1 month, and S- and L-cone loss that progresses for up to 6 months. Thus, OHT results in severe damage to both the innermost and the ORL.

• Authors: Arturo Ortín-Martínez, Manuel Salinas-Navarro, Francisco Manuel Nadal-Nicolás, Manuel Jiménez-López, Francisco Javier Valiente-Soriano, Diego García-Ayuso, José Manuel Bernal-Garro, Marcelino Avilés-Trigueros, Marta Agudo-Barriuso, María Paz Villegas-Pérez, Manuel Vidal-Sanz
• Journal: Experimental eye research (Exp Eye Res) Vol. 132 Pg. 17-33 (Mar 2015) ISSN: 1096-0007 [Electronic] England
• PMID: 25576772 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Chemical References

• Opsins

Topics

• Animals
• Blotting, Western
• Cell Count
• Disease Models, Animal
• Female
• Laser Coagulation (adverse effects)
• Ocular Hypertension (etiology, pathology)
• Opsins (metabolism)
• Rats
• Rats, Sprague-Dawley
• Retina (pathology)
• Retinal Cone Photoreceptor Cells (pathology, radiation effects)
• Retinal Ganglion Cells (pathology, radiation effects)