Localization of Taurine Transporter and Zinc Transporters in Rat Retinal Cells and Tissue. Effect of Intracelular Zinc Chelation.

Abstract

Asarí Márquez, Víctor Salazar, Lucimey Lima

Background: Possible colocalization of taurine and zinc transporters (TAUT, ZnT) has not been explored in the retina, although taurine-zinc interactions play physiological, and pathological roles. The objectives of the present work were to identify TAUT and ZnT-1,3,7 in rat retinal cells and layers and to explore effects of decreased zinc on them by immunochemistry and immunohistochemistry, respectively. Methods: Specific first antibodies and secondary antibodies, conjugated with rhodamine or fluorescein-isothiocyanate were used. Observations were done in a Nikon DIC fluorescence microscope. About 300 cells were counted per condition, and each value corresponded to an individual rat. Results: From total retinal cells, ganglion cells (GC) were 12-15%, and glial cells (GliC) 20-25%. TAUT and ZnT-1,3,7 were in 32, 29, 28 and 29% of total cells, respectively. TAUT, ZnT-1,3,7 were located in 64, 63, 53 and 72% of GC, and 57, 66, 82 and 66% of GliC, respectively. Significantly higher number of GC expressed ZnT-3 than GliC. Colocalization of TAUT and ZnT-1,3,7 was around 20%. Highest presence of TAUT was in photoreceptors, internal nuclear, and ganglion cells layers. ZnT-1,3 were mainly concentrated in photoreceptors, outer plexiform, and ganglion cells layers. ZnT-7 was high in photoreceptor and outer nuclear layers. The reduction of zinc, by the intracellular chelator (19-39%) in the retina, significantly decreased TAUT in all layers, except photoreceptors, indicating that the presence of zinc is necessary for its maintenance in this structure. Conclusions: Differential distribution correlates taurine and zinc with prospective functional consequences, such as emission of neurites, metabolic regulation, and signal transduction of the retina.