Abstract
Purpose: :
For pathogenic mechanisms of the glaucomatous neural degeneration, a variety of experimentally evoked ischemic models were used. The present study was aimed to investigate whether the attitudes of the neural cells differentially appeared in ischemic retinas, which were evoked by ischemia/reperfusion and by venous cauterization, respectively.
Methods: :
Elevated intraocular pressure (EIOP) model was made by air injection through anterior chamber with 120 mmHg pressure for 1 hour and reperfusion using Sprague-Dawley rats. Venous cauterization was done on three episcleral veins. Neuronal cells were analyzed by calbindin, nNOS and ChAT immunohistochemistry, and glial cells by Griffonia simplicifolia Isolectin (GSI) B4 and GFAP immunohistochemistry.
Results: :
Calbindin was expressed in the horizontal cells, amacrine cells and ganglion cells at normal state. In EIOP retina, calbindin expression is slightly down-regulated in the ganglion cells than those in normal and cauterization. nNOS was expressed in the amacrine and displaced amacrine cells and a population of the bipolar cells at normal. nNOS expressed bipolar cells are slightly increased in cell number of the cauterized retina. ChAT was expressed in the amacrine and displaced amacrine cells. In EIOP retina, ChAT expression is slightly down-regulated than those in normal and cauterization. In normal, GSIB4 labeled microglia appeared in the inner plexiform layer (IPL) near the blood vessels in addition to the endothelial cells. Microglia appeared even in the IPL of the early EIOP (to 1week), those in cauterized retina were in the IPL. GFAP expression was in the astrocytes in the nerve fiber layer and the ganglion cell layer at normal. GFAP expression in EIOP retina was in the radial processes of Mueller glial cells additionally, and that in cauterization similar but gradually down-regulated.
Conclusions: :
These results suggest that there is no large specific neuronal cell activation but remarkable glial cell activation in the rat retina in response to ischemia/reperfusion injury or venous cauterization.
Keywords: ischemia • intraocular pressure • retinal glia