Enriched environment decreases retinal susceptibility to ischemic damage

Abstract

Purpose :
Ischemia is a key component of several retinal diseases that are leading causes of irreversible blindness. At present, there are no effective strategies to prevent retinal ischemic damage. Enriched environment (EE) refers to conditions that facilitate or enhance sensory, cognitive, motor, and social stimulation relative to standard (laboratory) conditions. The aim of the present work was to analyze whether the exposure to EE prevents acute retinal ischemic damage.

Methods :
Adult male Wistar rats were housed instandard environment (SE) or EE for 3 weeks. SE consisted in standard laboratory cages, housing 2 animals/cage, and EE consisted in big cages housing 6 animals and containing several food hoppers, wheels and different objects repositioned once/day and fully substituted once/week. In SE and EE, animals were provided with food and water ad libitum. After 3 weeks of SE or EE, retinal ischemia was induced by increasing intraocular pressure above120 mm Hg for 40 min.
Immediately after ischemia, both groups were further housed in SE for 2 weeks.Retinal function (electroretinography, ERG),histology (H&E), Muller cells (glial fibrillary acidic protein, (GFAP immunoreactivity)) and retinal ganglion cell (RGC) number
(Brn3a immunohistochemistry) were assessed.

Results :
In animals housed in SE, ischemia induced a significant decrease in ERG a- and b- wave amplitude and oscillatory potentials, whereas the previous exposure to EE prevented these functional alterations. Two weeks after ischemia, a significant decrease in the total retinal thickness and the number of Brn3a(+) cells, as well as an increase in Muller cell GFAP levels werefound in retinas from animals housed in SE, whereas in ischemic retinas from animals housed in EE,theseparameters were significantly preserved.

Conclusions :
These results suggest that the exposure to EE prevents retinal alterations induced by acute ischemia.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.