Phosphodiesterase inhibition induces retinal degeneration, oxidative stress and inflammation in cone-enriched cultures of porcine retina.

Abstract

Inherited retinal degenerations affecting both rod and cone photoreceptors constitute one of the causes of incurable blindness in the developed world. Cyclic guanosine monophosphate (cGMP) is crucial in the phototransduction and, mutations in genes related to its metabolism are responsible for different retinal dystrophies. cGMP-degrading phosphodiesterase 6 (PDE6) mutations cause around 4-5% of the retinitis pigmentosa, a rare form of retinal degeneration. The aim of this study was to evaluate whether pharmacological PDE6 inhibition induced retinal degeneration in cone-enriched cultures of porcine retina similar to that found in murine models. PDE6 inhibition was induced in cone-enriched retinal explants from pigs by Zaprinast. PDE6 inhibition induced cGMP accumulation and triggered retinal degeneration, as determined by TUNEL assay. Western blot analysis and immunostaining indicated that degeneration was accompanied by caspase-3, calpain-2 activation and poly (ADP-ribose) accumulation. Oxidative stress markers, total antioxidant capacity, thiobarbituric acid reactive substances (TBARS) and nitric oxide measurements revealed the presence of oxidative damage. Elevated TNF-alpha and IL-6, as determined by enzyme immunoassay, were also found in cone-enriched retinal explants treated with Zaprinast. Our study suggests that this ex vivo model of retinal degeneration in porcine retina could be an alternative model for therapeutic research into the mechanisms of photoreceptor death in cone-related diseases, thus replacing or reducing animal experiments.

• Authors: Cristina Martínez-Fernández de la Cámara, Ma Dolores Sequedo, Ulises Gómez-Pinedo, Teresa Jaijo, Elena Aller, Patricia García-Tárraga, José Manuel García-Verdugo, José María Millán, Regina Rodrigo
• Journal: Experimental eye research (Exp Eye Res) Vol. 111 Pg. 122-33 (Jun 2013) ISSN: 1096-0007 [Electronic] England
• PMID: 23578797 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2013 Elsevier Ltd. All rights reserved.

Chemical References

• Phosphodiesterase Inhibitors
• Purinones
• Calpain
• Caspase 3
• zaprinast
• Cyclic GMP

Topics

• Animals
• Apoptosis (drug effects)
• Calpain (metabolism)
• Caspase 3 (metabolism)
• Cyclic GMP (metabolism)
• In Situ Nick-End Labeling
• Organ Culture Techniques
• Oxidative Stress (drug effects)
• Phosphodiesterase Inhibitors (pharmacology)
• Purinones (pharmacology)
• Retinal Cone Photoreceptor Cells (drug effects, pathology)
• Retinal Degeneration (chemically induced, immunology, metabolism)
• Retinitis Pigmentosa (chemically induced, immunology, metabolism)
• Swine
• Swine, Miniature