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J. De Juan, J. M. Romero del HombreBueno, N. Martínez-Ruiz, A. García-Alcaraz; Amacrine and Müller Cells Have Different Immunoreactivity for Aquaporin 4 in Light and Dark Adapted Teleost Retinas. Invest. Ophthalmol. Vis. Sci. 2010;51(13):895.
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© ARVO (1962-2015); The Authors (2016-present)
Aquaporins (AQPs) are membrane proteins that facilitate water transport across biological membranes, being essential for the correct function of the visual system. Although AQPs have been described for most cellular types in the mammalian retina, their identity in teleosts fish retinas remain unknown. In turn AQP4, expressed in mammalian Müller cells, has an important role in the maintenance of extracellular potassium homeostasis. We investigated the immunoreactivity of AQP4, in teleost fish retina during light/dark adaptation.
The study was performed in two species of teleosts: Dicentrarchus labrax and Sparus aurata. Animals were maintained on a daily 12 h light/dark cycle. Fish were light- and dark-adapted at least 2 hours prior to sacrifice. Dark-adapted animals were sacrificed under dim red light. We investigated the expression pattern and the identity of AQP4 immunoreactive cells by immunocytochemistry
AQP4 immunoreactivity was present in both species for amacrine cells at the Inner Nuclear Layer and its processes through the inner plexiform layer. In addition, Müller cells were also immunoreactive, being strongly labelled for S. aurata. No differences between light/dark adaptation were observed in D. labrax. However, AQP4 immunoreactivity for Müller cells in S. aurata was stronger in light condition. Co-localization studies with GAD67 showed the GABAergic type identity of AQP4 immunoreactive amacrine cells in D. labrax.
Amacrine and Müller cells are immunoreactive for AQP4 in teleost retinas, and show different cell expression patterns specie dependent. In addition, AQP4 immunoreactivity for S. aurata changes between light- and dark- adapted retinas. The presence of AQP4 in the teleost retina could be indicative of water redistribution through different retinal cells and its implication in potassium regulation at the inner retina.
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