Abstract
Abstract: :
Purpose: We have previously localized COX-1 and COX-2 to cells of the retina. The product of these enzymes, prostaglandin E2, may act on retinal neurons that can have different subtypes of prostaglandin receptors. We have determined the cellular localizations of prostaglandin receptor subtypes EP2 and EP3 in the normal mouse, rat and human retina. Methods: By using specific antibodies, we performed immunohistochemistry on wax sections of retinas and immunoblot analyses on retinal homogenates from mice, rats and humans. Results: In the normal mouse and rat retinas, EP2 receptor immunoreactivity was present in nerve fibers of the outer plexiform layer, horizontal cells, bipolar cells, amacrine cells, and the processes of Müller cells. In the normal human retina, EP2 receptor immunoreactivity was present in nerve fibers of the outer plexiform layer, horizontal cells, bipolar cells, amacrine cells, and nerve fibers in the ganglion cell layer. The presence of EP2 was confirmed by immunoblot in homogenates of mouse, rat and human retinas. In the normal mouse and rat retina, EP3 receptor immunoreactivity was present in nerve fibers of the outer plexiform layer, horizontal cells, amacrine cells, nerve fibers of the inner plexiform layer, displaced amacrine cells, and retinal ganglion cells. In the normal human retina, EP3 receptor immunoreactivity was present in the inner segments of photoreceptors, nerve fibers of the outer plexiform layer, horizontal cells, amacrine cells, displaced amacrine cells, and retinal ganglion cells. The presence of EP3 was confirmed by immunoblot in homogenates of mouse, rat and human retinas. Conclusions: Our findings suggest that prostaglandin receptor subtypes EP2 and EP3 are widely distributed in the normal retina. The differential distributions of EP2 and EP3 receptors provide cellular sites of action for studies of the functions of the product of COX, prostaglandin E2, in the retina.
Keywords: retina: proximal(bipolar, amacrine, and gangli • retina: distal(photoreceptors, horizontal cell • receptors: pharmacology/physiology