Taurine and Retinal Ganglion Cell Survival Across the Lifespan

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Excerpt:
IntroductionTaurine is a nutrient-rich amino sulfonic acid found in high concentrations in the retina and other neural tissues. In fact, taurine levels in the retina are higher than in any other body tissue, and its depletion causes retinal cell damage (). Adequate taurine is known to be essential for retinal neurons, especially the photoreceptors and retinal ganglion cells (RGCs). RGC degeneration underlies vision loss in glaucoma and other optic neuropathies. Preclinical research now suggests that taurine can help maintain RGC health. This article reviews how taurine regulates cell volume and calcium to protect RGCs, the evidence from laboratory models that taurine promotes RGC survival, and the limited clinical data hinting at vision benefits. We also discuss how diet and aging affect taurine levels, related health outcomes, and what is known about safe taurine supplementation and priorities for future trials.Taurine in the Retina: Osmoregulation and Calcium HomeostasisTaurine plays key cellular roles beyond being a nutrient. In the retina it acts as an organic osmolyte, helping cells adjust their volume under stress. Retinal cells (including RPE, RGCs, and Müller glia) express the taurine transporter (TauT) to import taurine. Under hyperosmotic stress (such as high salt or sugar conditions), TauT expression and activity increase, causing cells to uptake more taurine and water. This protects retinal cells from shrinkage or swelling () (). In other tissues (like brain astrocytes) taurine effluxes out in hypotonic conditions, allowing cells to maintain osmotic balance. Thus, taurine is fundamental to osmoregulation in the retina, buffering RGCs against fluid stress that can occur in diabetes or infarction () ().Taurine also helps regulate intracellular calcium (Ca2+), a critical factor in neuron survival. Excess cytosolic Ca2+ can trigger mitochondrial damage and cell death. Taurine influences calcium by several mechanisms. In RGCs and other neurons, taurine has been shown to increase the capacity of mitochondria to sequester Ca2+, thereby lowering harmful free cytosolic Ca2+ (). It also modulates calcium influx through voltage-gated Ca2+ and sodium channels, acting somewhat like a natural calcium channel regulator (). By reducing intracellular calcium spikes, taurine prevents the opening of mitochondrial permeability pores and the apoptotic cascades they can trigger (). In short, taurine helps keep RGC calcium homeostasis in check, which in turn protects mitochondria and prevents calcium-driven injury () ().Oxidative Stress and NeuroprotectionBeyond osmoregulation and calcium, taurine is a potent antioxidant and neuroprotectant. It can directly scavenge reactive molecules such as hypochlorous acid, and it helps preserve the activity of key antioxidant enzymes. In retinal models, taurine supplementation boosts glutathione levels and enzymes like superoxide dismutase and catalase () (). By reducing oxidative stress, taurine helps prevent the oxidative damage that is a major cause of retinal degeneration. Taurine has also been linked to anti-apoptotic pathways: it tends to down-regulate pro-death proteins and up-regulate survival proteins in neurons () (). For example, in CNS cells taurine inhibits caspases and calpains (enzymes involved in apoptosis) and maintains a healthy balance of Bcl-2 family proteins ().
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Видео Taurine and Retinal Ganglion Cell Survival Across the Lifespan канала Glaucoma, Vision & Longevity: Supplements Science