Abstract
Abstract: :
Purpose: To examine the expression of COX-2 in the retina and the optic nerve head in a rat glaucoma model. Methods: Adult Sprague Dawley albino rats, 45-50 day-old, were given unilaterally intravitreal injection of India ink and trabecular laser photocoagulation was delivered at 7 days after injection. Intraocular pressure (IOP) was monitored. Eyes were enucleated at 0.5, 1, 3, 5, 7, and 14 days after photocoagulation. For a control group, laser photocoagulation was delivered to the mid-iris stroma after ink injection. The eyeballs were enucleated, bisected and processed for immunohistochemistry with antibody against COX-2 and TdT-mediated biotin-dUTP nick end labeling (TUNEL). A minimum of 6 eyes was examined for each group. Results: Significantly elevated IOP was noted 3 (69%), 5 (48%), and 7 (63%) days after photocoagulation when compared with the control contralateral eyes (P < 0.05; n = 61). There was a maximal number of TUNEL positive cells in the inner retinas at 5 days after photocoagulation (P < 0.01). Parallel to the increased number of TUNEL positive cells, there were scattered COX-2 immunopositive cells in the inner plexiform layer (IPL) and mildly increased COX-2 immunoreactivity in IPL at 5 and 7 days. There were no noticeable changes in other retinal layers and in the control retinas. In the optic nerve head, there were COX-2 immunoreactivity in control eyes and a generalized loss of immunoreactivity 14 days after photocoagulation. Conclusions: COX-2 may play an important role in the pathophysiology of experimental glaucoma.
Keywords: apoptosis/cell death • ganglion cells • retinal degenerations: cell biology