Adenosine receptor A2A expression in light induced retinal degeneration.

SOLIÑO M, LÓPEZ EM, MARTIGNONE N, VACOTTO M, GIRARDI E, LÓPEZ COSTA JJ.

rio de janeiro

Congreso; IBRO-9th World Congress International Brain Research Organization; 2015

IBRO/LARC

IBRO - 9th World Congress International Brain Research Organization http://ibro2015.org« Back to searchPT - 583 - POSTER SESSION II - DISORDERS OF THE NERVOUS SYSTEM 09/07/2015 de 08:00 às 17:30, POSTER SESSION 752 - ADENOSINE RECEPTOR A2A EXPRESSION IN LIGHT INDUCED RETINAL DEGENERATION MANUEL SOLIÑO; ESTER MARÍA LÓPEZ; NOELÍ MARTIGNONE; MARINA VACOTTO; ELENA GIRARDI; JUAN JOSÉ LÓPEZ-COSTA. IBCN "P.E. DE ROBERTIS", UBA-CONICET, BUENOS AIRES - ARGENTINA .Palavras-chave: RETINA;DEGENERATION;ADENOSINEContinuous illumination (CI) of rat retina produces photoreceptor degeneration. It resembles retinal degenerative diseases as retinitis pigmentosa and Age related Macular Degeneration (AMD, first cause of acquired blindness in developed countries).A2a receptor (A2aR) has been described in the retina and has been linked to the control of the characteristics of the subretinal space. It was also seen that it plays a role in inflammation, neuronal and trophic factor activity. In recent years, the modulation of A2aR has emerged as an effectiveneuroprotective strategy to treat a wide range of CNS pathologies.In order to shed some light on the processes underlying retinal degenerations and to evaluate a potential therapeutic target, we decided to study A2aR distribution in control (CTL) and illuminated (IL) rat retinas by immunocytochemistry (ICC), Western blot (WB) and RT-PCR.Sprague Dawley rats were submitted to CI (12000 lux) during 1, 2, 5 and 7 days. Its eyes were extracted and processed by ICC. Other two groups of animals had its retinas extracted and processed by RT-PCR or by WB. We used an A2aR rabbit polyclonal antibody (Santa Cruz Int.) as primary antibody. Results were quantified by image analysis using the software Fiji and Image Light Studio. Data was statistically analysed using one-way analysis of variance tests (ANOVA).In the ICC, the average optical density (OD) was measured for the whole retina and each individual layer separately. Control animals showed strong A2aR immunoreactivity (A2a-IR) on the ganglion cell layer (GCL), the inner nuclear layer (INL), the outer plexiform layer (OPL), and the outer portion of the inner plexiform layer (IPL). A weaker staining was observed in the outer nuclear layer (ONL) and the photoreceptor layer (PH). After illumination, there were two significant rises in the average OD, the first at 48 HS and then again at 5 days of illumination (P<0.0001). The WB studies showed a decrease of A2AR in animals illuminated for 24 Hs (IL 24) retina followed by increments in the relative density, only the observed increment of A2aR levels at 5 day of CI was significant compared to control levels (P<0.05).RT-PCR results showed a significant up-regulation of A2AR mRNA at 1, 5 and 7 days after CI. However, this was not significant after 48 hs and A2R mRNA peaked at 24 hs and 7 days (P<0.0001).Our results show that, as retinal injury progresses, A2aR shifts in its expression, rising its levels at two moments preceded by an increment in its ARNm. To us, this is particularly interesting because it is happening before the massive PH apoptosis seen at 2 days of CI. As this receptor is known to be a potential road to neuroprotection and is linked with many key proceses regarding cell survival in general and in the retina in particular, we postulate that its modulation could delay or prevent PH degeneration if the retina is treated at a precise moment. (Supported by CONICET PIP1098 and UBACYT 20020100100329).