Serial study of Apoptosis and Morphologic Change of Retina in Experimental Model of Chronic Retinal Ischemia in Rats

ABSTRACT

PURPOSE: We investigated the serial developement of programmed cell death or apoptosis as a mechanism of cell death by inducing chronic retinal ischemia in experimental permanent common carotid artery ligation in rats. We also hope this model to be applied in study of normal tension glaucoma or ischemic ocular disease. METHODS: After ligation of both common carotid arteries of rats under anesthesia, they were sacrificed on the 1st, 3rd, 5th, 7th, 14th, 28th, and 63rd day and then enucleation was done. After separating retina, we did TdT-dUTP nick-end labeling (TUNEL)stain and Bax immunochemistry stain to study apoptotic change and we also did hematoxylin eosin stain to evaluate retinal morphologic changes. RESULTS: Apoptotic cells were showed in ganglion cell layer cheifly on TUNEL stain and Bax immunochemistry stain on the first day after ligation of common carotid artery, as time as gone, apoptotic cell increased and then developed in all layers on the 28th day. Cell density decreased in ganlion cell layer, inner nuclear layer, and outer nuclear later on hematoxylin eosin stain on the third day; as time as gone, cell density further decreased and thickness of inner plexiform layer and nuclear layer decreased also. CONCLUSIONS: This result shows that apoptosis has the important role in the cell death at the ischemic retina. The results of this study will also provide baseline information for the further study on normal tension glaucoma or ocular ischemic diseases compared to transient retinal ischemia model induced by elevation of intraocular pressure.