Reaction of Muller cells after increased intraocular pressure in the vet retina

Using light microscopy and immunocytochemistry, we investigated the morphological changes of retinal tissues and the reaction of Muller cells in the ischemic rat retina induced by increasing intraocular pressure. At early stages (from I h to 24 h after reperfusion), cells in the ganglion cell layer and in the inner nuclear layer showed some degenerative changes, but at later stages (from 72 h to 4 weeks) marked degenerative changes occurred in the outer nuclear layer (ONL). At 4 weeks after reperfusion, the ONL was reduced to 1 or 2 cell layers. Immunoreactivity for glial fibrillary acidic protein (GFAP) appeared in the endfeet and distal processes of Muller cells as of 1 h after reperfusion. GFAP immunoreactivity in Muller cells increased up to 2 weeks and then decreased at 4 weeks after reperfusion. Our Endings suggest that Muller cells are involved in the pathophysiology of retinal ischemia through the expression of GFAP. The degree of GFAP expression in Muller cells closely correlated with that of the degeneration of retinal neurons.