Abstract
Purpose:
The endothelin system of peptides and their receptors have been implicated for their neurodegenerative role in glaucoma. The purpose of this study was to determine changes in the ETA receptor expression in the retina in the Morrison’s elevated IOP model of glaucoma in rats.
Methods:
IOP was elevated in the left eye of adult male retired breeder Brown Norway rats using the Morrison’s model of glaucoma (by injection of hypertonic saline through episcleral veins) while the contralateral eye served as the control. The rats were maintained for two to four weeks following IOP elevation and sacrificed. Retinal sections were obtained from both control and IOP-elevated eyes, and analyzed for changes in ETA receptor expression using immunohistochemistry. ETA receptor immunostaining was co-localized with β-III-Tubulin, which is selectively expressed in retinal ganglion cells.
Results:
After two weeks of IOP elevation, rat eyes with IOP elevation showed an increase in immunostaining for ETA receptors in several retinal layers including the inner and outer plexiform layers, with a modest increase in the retinal ganglion cell layer. Following four weeks of IOP elevation, ETA receptor expression was slightly increased in the inner and outer plexiform layers of the retina, compared to that in the corresponding contralateral eyes.
Conclusions:
Elevated intraocular pressure results in a time-dependent change in ETA receptor expression. Increased ETA receptor expression is associated with neurodegenerative changes in glaucoma.
Keywords: 688 retina •
568 intraocular pressure •
675 receptors: pharmacology/physiology