Expression of aquaporin-1 immunoreactivity by photoreceptor cells in the mouse retina

Aquaporin water channels play a crucial role in the maintenance of ionic and osmotic homeostasis in the neural tissue. In the sensory retina, aquaporin-4 is expressed by Muller glial cells, predominantly in the inner retina, while aquaporin-1 is expressed mainly in the outer retina. However, it is unknown whether aquaporin-1 expression occurs in Muller cells or photoreceptor cells. By using immunohistochemical staining of retinal slices from rds mice, we show that the immumoreactivity for aquaporin-1 disappears along with the photoreceptor cell degeneration. In suspensions of dissociated retinal cells from control mice, photoreceptor cells expressed aquaporin-1 immunoreactivity while Muller cells were largely devoid of staining. The data suggest that photoreceptor cells, but not Muller cells, express aquaporin-1 in the murine retina. (C) 2005 Elsevier Ireland Ltd. All rights reserved.