Up-Regulation of Cyclooxygenase-2 in N-Methyl-D-Aspartate-Treated Rat Retina

Abstract

Abstract: : Purpose: We examined the expression of cyclooxygenase-2 (COX-2) in rat retinas infused with the glutamatergic agonist N-methyl-D-aspartate (NMDA). Methods: Intravitreal injections of 2 µL of either 40 mM neutralized NMDA in 0.1M phosphate buffered saline or the vehicle alone were given to Sprague Dawley rats, 45-55 days old. Groups of animals were euthanized at 0, 3, 6, 9, 12, 18, 20, 24 and 36 hours and their eyes were enucleated. The retinas of some eyes were fixed, processed, embedded in paraffin, and sectioned. Immunohistochemistry for COX-2 was performed on these sections. Retinas of the remaining eyes were dissected and processed for Real-time RT-PCR analysis of COX-2. Results: Eyes injected with NMDA showed many COX-2-positive cells in the retinal ganglion cell layer and in the inner plexiform layer 18 hours after the infusion, while only a few COX-2-positive cells were noted in the control normal retinas. Semiquantitative Real-time RT-PCR demonstrated an up-regulation, above that of normal retinas, of COX-2 mRNA 6 to 12 hours after treatment with NMDA. Conclusions: COX-2 is up-regulated in the rat retina after NMDA-induced excitotoxicity.

Keywords: cytokines/chemokines • retinal degenerations: cell biology • immunohistochemistry