Abstract
Purpose :
Retinal ischemia plays a central pathophysiological role in numerous eye diseases, including glaucoma. Along with apoptosis, autophagy is one of the cell death mechanisms downstream of ischemia. However, its role is still seen controversial. The aim of this study was to investigate whether and when autophagy occurs in the animal model of retinal ischemia.
Methods :
Retinal ischemia was induced in 6-8-weekold mice by increasing intraocular pressure to 90 mmHg for 45 min. 3 and 12 hours later, ischemic and control retinas were analyzed immunohistochemically (n=7/group/time point) and by Western blot analyzes (n=5/group/time point) with markers for retinal ganglion cells (RGC; Brn-3a), macroglia (GFAP) and autophagy (LC3, p62, LAMP1).
Results :
Immunohistochemical investigations revealed that retinal ischemia resulted in significant RGC loss 3 (p=0.005) and 12 hours (p≤0.001) after ischemia. In addition, a significant macrogliosis was detectable after 12 hours (p≤0.001). Analyzing the autophagy pathway, a significant increase in the early autophagy marker LC3 was evident in the RGCs after 3 (p=0.041) and 12 hours (p≤0.001). The late autophagy marker LAMP1 was significantly increased only after 12 hours (p=0.039). Furthermore, after 3 (p=0.036) and 12 hours (p≤0.001) a significantly increased p62 expression was detectable immunohistochemically. Western blot analyzes confirmed the upregulated p62 expression after 12 hours (p=0.003).
Conclusions :
Our results show that ischemia-induced retinal damage is associated with autophagy activation at a very early stage. The accumulation of p62 protein suggests that there are impairments in the autophagic flux after ischemia, potentially exacerbating ischemic damage. This better understanding of autophagic regulation and its effect on cell death regarding retinal ischemia may lead to novel neuroprotective strategies using autophagic modulating.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.