Abstract
Abstract: :
Purpose: Glaucoma is known to not only cause apoptotic death of retinal ganglion cells (RGCs) but also alter glial reactivity. However, long–term effect of elevated intraocular pressure (IOP) on glial reactivity has not been fully elucidated. The purpose of this study is to examine how chronically elevated IOP in unilateral eyes affect reactivities of astrocytes and Müller cells in the treated as well as contralateral eyes over time. Methods: Three episcleral veins in unilateral eyes of Sprague–Dawley rats were cauterized to chronically elevate IOP. Retinas were taken at several time points until 6 months, during which IOPs were monitored by Tonopen® under urethane anesthesia. Flat mount retinas were subjected to terminal dUTP nick end labeling (TUNEL) staining or immunostaining against glial fibrillary acidic protein (GFAP). One– or two–dimensional electrophoresis followed by immunoblotting for GFAP was also conducted for some groups of retina samples. Results: The cauterization significantly increased TUNEL positive cells in an IOP–dependent fashion as previously reported (Kanamori et al. Curr Eye Res, In Press). In the treated eyes of whole mount retinas, astrocytes reduced and Müller cells gained GFAP immunoreactivity at 3 days after cauterization, which were partially reversed over time. Surprisingly, in the contralateral eyes, similar changes of GFAP immunoreactivity appeared at and after 3 months of cauterization. Immunoblotting demonstrated not only molecular size shifts but also alteration of isoelectric focusing of GFAP. Conclusions: Dynamic changes of glial reactivity occur not only in treated but also contralateral retinas in a rat experimental glaucoma model.
Keywords: retinal glia • intraocular pressure • immunohistochemistry