Consequences of zinc deficiency on zinc localization, taurine transport, and zinc transporters in rat retina.

The colocalization of taurine and zinc transporters (TAUT, ZnTs) has not been explored in retina. Our objective is to evaluate the effect of the intracellular zinc chelator N,N,N,N-tetrakis-(2-pyridylmethyl) ethylenediamine (TPEN) on zinc localization and colocalization TAUT and ZnT-1 (of plasma membrane), 3 (vesicular), and 7 (vesicular and golgi apparatus) in layers of retina by immunohistochemistry. To mark zinc, it was used cell-permeable fluorescent Zinquin ethyl ester. Specific first and secondary antibodies, conjugated with rhodamine or fluorescein-isothiocyanate were used to mark TAUT and ZnTs. The fluorescence results were reported as integrated optical density (IOD). Zinc was detected in all layers of the retina. The treatment with TPEN produced changes in the distribution of zinc in layers of retina less in the outer nuclear layer compared with the control. TAUT was detected in all layers of retina and TPEN chelator produced decrease of IOD in all layers of retina except in the photoreceptor compared with the control. ZnT 1, 3, and 7 were distributed in all retina layers, with more intensity in ganglion cell layer (GCL) and in the layers where there is synaptic connection. For all transporters, the treatment with TPEN produced significant decrease of IOD in layers of retina least in the inner nuclear layer for ZnT1, in the photoreceptor for ZnT3 and in the GCL and outer plexiform layer for ZnT7. The distribution of zinc, TAUT, and ZnTs in the layers of retina is indicative of the interaction of taurine and zinc for the function of the retina and normal operation of said layers. HIGHLIGHTS: Taurine and zinc are two molecules highly concentrated in the retina and with relevant functions in this structure. Maintaining zinc homeostasis in this tissue is necessary for the normal function of the taurine system in the retina. The study of the taurine transporter and the different zinc transporters in the retina (responsible for maintaining adequate levels of taurine and zinc) is relevant and novel, since it is indicative of the interactions between both molecules in this structure.