Abstract
Purpose: :
Recent studies suggested that autophagy plays a role in a neural death pathway after ischemia, but the role of autophagy in retinal damage resulting from ischemia-reperfusion (IR) is not known. We investigated the time-dependent changes in the activation of autophagy in the murine model of IR.
Methods: :
Unilateral retinal IR was induced in 55 adult C57BL/6 mice by cannulating the anterior chamber of the globe and transiently elevating the intraocular pressure for 60 min. Untreated eyes served as controls. After day 1, 2 and 7 of reperfusion the animals were sacrificed and the markers of autophagy as light chain 3 (LC3-I and II), beclin-1 and autophagy-related gene 5 (atg-5) were investigated using western blot techniques and immunohistochemistry. Further, the gene expression of LC3 and beclin-1 was investigated by using real-time PCR.
Results: :
Retinal ischemia resulted in a rapid activation of autophagy presented by significant increase of LC3-II, beclin-1 and atg-5 detected by western blotting. The highest amount of LC3-II and atg-5 was found on day 1 after IR whereas the presence of beclin-1 protein increased continuously from day 1 to day 7 after IR. The gene expression of LC3 and beclin1 reached the highest upregulation on day 1 after IR and decreased gradually in subsequent days. But compared to untreated control eyes on day 7 there was still significant upregulation of these genes.
Conclusions: :
Our study showed that the autophagy is activated after retinal ischemia-reperfusion injury. Such activation was prominent on day 1, however, there was some level of autophagic activity day 7 after retinal ischemia suggesting that autophagy could play a role in ischemic damage of the retina.
Keywords: ischemia • apoptosis/cell death • retina