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Abstract #6329 Published in IGR 3-2
Constitutive expression and localization of COX-1 and COX-2 in rabbit iris and ciliary body
Damm J; Rau T; Maihöfner C; Pahl A; Brune KExperimental Eye Research 2001; 72: 611-621
Prostaglandins (PG) are involved in the regulation of intraocular pressure and the blood-aqueous barrier of the eye, and are used for the treatment of glaucoma. The decrease of the constitutively expressed PG-synthesizing enzyme cyclo-oxygenase-2 (COX-2) has been demonstrated in the ciliary non-pigmented epithelial layer of patients with primary open-angle glaucoma. Little is known about the distribution of COX-1 and COX-2 in animals. The authors investigated this in the iris and ciliary body of the normal rabbit eye. The presence of COX-1 and COX-2 in freshly excised iris and ciliary body tissue from adult New Zealand White albino rabbits was demonstrated by real-time RT-PCR, and western blot analysis. The localization of both isoforms of the neuron-specific protein gene product 9.5 was determined by indirect immunofluorescence. Both enzymes are expressed in the iris and ciliary body. Immunofluorescence studies including double staining techniques localized COX-1 and COX-2 to about 50% of cells in the stromal tissue of the iris and ciliary body, mainly on the corneal side. They were co-localized in about 75% of these cells. While all stained cells were positive for COX-1, COX-2 showed a gradient-like distribution in the stroma, with some restriction of expression near the epithelial layers, which was clearly shown to be completely negative for both COX-1 and COX-2. Also, neuronal elements did not show COX-1 or COX-2 immunoreactivity. These results establish the presence of COX-1 and COX-2 on the RNA and protein levels in normal, unstimulated rabbit iris and ciliary body. The pattern of distribution suggests a role for both enzymes in maintaining the physiology of the eye. In contrast to the authors' results in humans, nonpigmented epithelial cells of the ciliary body did not express immunoreactivity. This could account for differences in the regulation of intraocular pressure and/or the blood-aqueous barrier between human and rabbit eyes.
Dr J. Damm, Institute for Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nuremberg, Erlangen, Germany
Classification:
2.8 Iris (Part of: 2 Anatomical structures in glaucoma)
2.9 Ciliary body (Part of: 2 Anatomical structures in glaucoma)
5 Experimental glaucoma; animal models
3.4 Molecular genetics (Part of: 3 Laboratory methods)
