Visual input plays a key role in the retinal protection induced by enriched environment against acute retinal ischemia

DORFMAN D; ARANDA ML; GONZÁLEZ FLEITAS MF; DIEGUEZ HH; KELLER SARMIENTO MI; ROSENSTEIN RE

Seattle

Congreso; ARVO Annual Meeting 2016; 2016

PURPOSE:Enriched environment (EE) constitutes astrategy that boosts locomotor, exploratory, visual,and cognitive activities, aswell as social interaction and voluntary physical exercise.Ischemia is a keycomponentof several retinal diseases that are leading causes of irreversibleblindness. We have shown that the exposure to EE protects the retina againstacute unilateral ischemia in adult rats.In this work, we analyzedthe involvementof visual processing in the protection induced by EE against retinal ischemicdamage. METHODS: Adult male Wistar rats were submitted to acute unilateral or bilateralischemia by increasing intraocular pressure to 120 mm Hg for 40 min. Afterunilateral ischemia, animals wereexposed to a standard environment (SE), a noveltyenvironment (NE), or an EEfor 3 weeks.NE consisted in standard laboratorycages, housing 2 animals and containing novelty objects that were weeklysubstituted, whileEE consisted of big cages housing 6 animals, and containingfood hoppers, wheels and different objects repositioned once/day and fullysubstituted once/week.Animals submitted to bilateral ischemia were exposed toSE or EE for 3 weeks. Retinal function (electroretinography, ERG), andhistology were analyzed at 3 weeks post-ischemia. Locomotor activityin EE wasanalyzed in animals exposed to unilateral or bilateral ischemia. The expressionof c-fos(immunofluorescence) in the retinorecipient layers of the superiorcolliculi (SC) was assessed in control animals, and animals submitted tounilateral or bilateral ischemia at 24 h of exposure to EE.RESULTS: Unilateral ischemia induced a significantdecrease in scotopic ERG a- and b- wave amplitude, and clear histopathologicalalterations. NE was ineffective in protecting the retinal function andstructure against unilateral ischemia. EE which preserved retinal function andhistology against unilateral ischemia, did not protect the retina in animalsexposed to bilateral ischemia, regardless that locomotor activity did notdiffer among groups. In animals submitted to unilateral ischemia, EE inducedc-fos expression in the SC receiving projections from control and ischemiceyes. However, when ischemia was bilaterally induced, c-fos expression wasabsent in neither SC.CONCLUSION: These results suggest that the protectioninduced by EE could involve visual processing information.