Abstract
Purpose :
Several eye diseases, e.g. retinal artery occlusion, diabetic retinopathy or glaucoma, are associated with retinal hypoxia (ischemia). The lack of oxygen in the retina, especially in retinal ganglion cells (RGCs), causes cell damage up to cell degeneration leading to blindness. To examine the activity of RGCs and analyze the effect of neuroprotective substances under hypoxic conditions is of great ophthalmologic interest.
Methods :
Using multielectrode array (MEA) recordings, two ex vivo models were established to analyze the electrical activity of murine wild-type (wt) retina under hypoxic stress conditions. In model 1, hypoxic conditions were initiated by stopping the perfusion with oxygen saturated medium. In model 2, hypoxia was induced by exchanging the perfusion with oxygen saturated medium by nitrogen saturated medium, which allowed for more precisely defined test conditions. To analyze the influence of neuroprotective agents on the firing behavior of RGCs under hypoxia-induced conditions, 2-aminoethanesulfonic acid (taurine, 1 mM) was added during a hypoxia time of 30 min.
Results :
In both models, the electrical activity vanished during hypoxia. However, it conditionally returned after reestablishment of the conventional test conditions. With increasing duration of hypoxia, the number of recording channels, on which activity could be redetected, decreased. After a hypoxic period of 30 min and a subsequent recovery time of 30 min, 52.14 ± 26.69 % of the initially active channels showed a restored activity within the first model, and 59.43 ± 11.35 % within the second. The application of taurine had a positive influence on the electrical excitability of RGCs. However, regarding the number of recording channels and the firing frequency of the spontaneous activity after hypoxia, no positive effects were observed.
Conclusions :
The hypoxia models established here allow for the analysis of electrical RGC activity before, during and after hypoxic conditions as well as the investigation of the effect of any protective substance on the retinal electric activity. Further experiments regarding the analysis of the RGC excitability after light stimulation are ongoing. For closer investigation of the effect of taurine, a microarray-based transcriptome-wide gene expression analysis of the retina has been performed using different culture conditions.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.