Aquaporin 1 expression in control and pathological rat retina

Aquaporin 1 (AQP1) is a transmembrane channel protein, present in various tissues including ocular tissues. It carries water and regulates cations flow across membranes. Experimental laser photocoagulation in rat retina induces reproducible injuries mimicking some angiogenic features of ocular pathologies, such as subretinal neovascularization and gliosis. This experimental model enables the study of repair mechanisms following these lesions. Our study was designed to observe the potential changes of AQP1 expression in such processes. We performed immunohistochemical AQP1 co-immunostaining combined with typical markers of retinal cell types: glial fibrillary acidic protein (GFAP) for Müller cells and astrocytes, a marker known to be involved in gliosis; von Willebrand factor (vWF), a typical marker of blood vessels and Nestin, a progenitor/stem cell marker in some contexts. We observed AQP1/GFAP co-immunolabeling principally in retinal Müller cells, while AQP1/vWF staining was seen in the choroid and retina. AQP1/Nestin co-immunolabeling was observed, in blood vessels of the ganglion cell layer (GCL) and choroid as well as in retinal blood vessels. In conclusion, after administration of laser impacts in the retina, we detected significant amounts of AQP1 in blood precursor cells. We also observed relocalization of AQP1 from Müller cell endfeet to the entire cell surface, which might be linked to the formation of inner retinal edema.