Abstract
Purpose :
Previous studies have shown that the deleterious effects of ischemia on retinal functionality can be alleviated by hypothermia. Here, we further highlight this effect by thoroughly investigating the effect of hypothermia on electrophysiological functionality resuscitation following prolonged ischemia.
Methods :
Using an isolated retina of a wild-type rat we investigated the effect of hypothermia on ischemia damage (15-240min at 21 or 37°C). Ischemia was induced at both the complete eyeball (following the desired treatment the retinal was isolated in an oxygenated solution) and the isolated retina level (on-chip ischemia in which the supply of oxygenated medium was switched on and off; oxygen content was found to be 13.5 mg/L and 8.7mg/L respectively). Next, several electrophysiological response features induced by 1sec flashes were investigated, namely: the number of active RGCs, the firing rate of the RGCs, and the amplitude of the various components of the electroretinogram.
Results :
On-chip experiments revealed that the percentage of cells whose response was restored following an ischemia of 15min at 37C period was ~100% decreasing to ~50% for 60min and to almost 0% for 120min ( p for trend =0.03). A significant decrease in the firing rate was also observed (p for trend <0.001). These results also revealed the more deleterious effect of ischemia on the OFF compared with the ON responses. A similar effect on the ERG amplitudes was also observed. At the complete eyeball level, we found a significant prolongation in the persistence of light-induced responses from 30min ischemia (under 37°C) to 240min (under 21°C).
Conclusions :
A model facilitating the investigation of ischemia-induced damage and the feasibility of response resuscitation through various interventions at the single-cell level was introduced. Further investigations are required to understand the effects at the molecular level.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.