Does taurine have a role in the phagocytic function of the retinal pigment epithelium?

Abstract

AbstractPurpose: To study the role of taurine in the morphology and phagocytic function of the retinal pigment epithelium (RPE) in normal and dystrophic rats.Methods: Albino Sprague–Dawley (SD) rats and pigmented dystrophic Royal College of Surgeons (RCS‐p+) rats that suffer a severe form of inherited photoreceptor degeneration due to RPE phagocytosis impairment, were used for this study. SD rats received β‐alanine in drinking water (3%) for 2 months from P21 to induce taurine depletion and RCS‐p + rats received taurine supplementation in drinking water (0.2 M) for 24 days from P21. Groups of untreated RCS and SD rats were used as control. SD rats were processed 2 months after the start of treatment, while RCS rats were processed at P45. Twenty‐four hours before processing, the animals received an intravitreal injection of 1.5 μl of 3% fluorogold (FG) diluted in saline 24 to label the RPE cells. Animals were processed and the RPE was dissected flat‐mounted and observed using a confocal microscope (Leica SP8).Results: In control SD animals, Fluorogold (FG) accumulates homogeneously in the cytoplasm of the RPE cells. Taurine‐depleted SD animals showed less FG accumulation in the cytoplasm in all cells and, and some cells had FG accumulation only in part of the cytoplasm or no FG accumulation at all. Untreated RCS‐p + animals showed an inverted accumulation of FG because it appeared mainly in the membrane of the RPE but not in the cytoplasm. Finally, taurine‐treated RCS‐p + animals showed FG accumulation in the cytoplasm of the RPE cells, although the accumulation of FG was smaller than that found in SD rats.Conclusions: Taurine influences the phagocytic capacity of the RPE cells. Taurine depletion impairs the phagocytic capacity of the RPE cells in healthy retinas, and taurine supplementation improves the phagocytic function of RPE cells in dystrophic RCS‐p + rats.