Taurine may prevent age related changes in the eye

Taurine

Taurine is available in the FitEyes eStore. One recommended product is L-Taurine Powder 300 grams by Life Extension.

Article by Robert Nussenblatt, MD

Taurine (2-aminoethanesulfonic acid) is the decarboxylation product of cysteine, and is mainly obtained from diet. It is a free sulfur ß-amino acid found in animal tissue and is one of the most abundant low molecular weight compounds, present in the micromolar range per gram wet weight. While the body can make taurine from sulfur precursers, it is produced endogenously in the liver from methionine and cysteine. Enzymes that are needed for taurine production include cysteine sulfinic acid decarboxylase, which is the rate limiting step in the cascade leading to taurine.(Militante & Lombardini 2004) However, the amount produced is insufficient and dietary sources are needed. Taurine is found freely in the cytosol and is found particularly in the heart, retina, brain and blood.

Taurine has been associated with many different physiologic activities, including calcium transport, antioxidation, neurotransmission, and regulation of protein phosphorylation.(Huxtable & Sebring 1986) It should be added that the dominant role of taurine still needs to be determined. Significant changes in plasma and tissue levels occur in aging rats.(Wallace & Dawson 1990) These decreases are noted in the eye as well (Eppler & Dawson 2001) and may be due to a decrease in liver biosynthetic enzymes. Of interest is that withdrawing taurine from the diet of animals does not enhance the decrease; yet augmenting the exogenous amount of taurine helps to resolve the deficit. However these observations are in the rat. In the human, the data is less robust. What has been shown is that taurine concentrations increase in the cerebrospinal fluid of aging humans (Tohgi et al. 1993), and by upwards of 30%.

As with other tissues, taurine is found in high concentrations in phagocytic cells. It is believed to provide protection against inflammatory cytotoxicity, anti-oxidant activity, and membrane stabilization. Taurine appears to mediate these effects by eliminating highly toxic HOCL and generating non-toxic TauCl. TauCl appears to suppress the production of many inflammatory mediators, including NO, TNF-alpha, IL-1, Il-2, and IL-6. It appears to suppress production of IL-10 as well, which is a downregulatory cytokine.(Schuller-Levis & Park 2004; Kim & Cha 2009) It would appear that taurine in phagocytes prevents chronic inflammatory processes. The underlying mechanisms in macrophages appears to be the inhibition of NO by the suppression of the activation of several factors, including Ras, ERK1/2, and NF-kB. In neutrophils, taurine appears to exert an inhibitory effect by inhibiting p47phox and the assembly of the NADPH-oxidase complex. (Kim & Cha 2009)

Taurine appears to play an important in ocular development. It appears structurally similar to the neurotransmitters GABA and glycine. Taurine plays a role aslo in the formation and maintenance of neural tissue. Kittens given taurine-deficient diets exhibited retinal degeneration and CNS defects.(Sturman 1986).

Interestingly, taurine increased the numbers of rod photoreceptors in retinal culture.(Altshuler et al. 1993) It appears to act in retinal progenitors via the GlyRa2 subunit containing glycine receptors.(Young & Cepko 2004)

As noted above, levels in animals decrease with aging, and specific ERG changes in rats can be associated with these decreased tissue levels, reflecting the fact that the retina has a decreased ability to deal with oxidative stress.(Militante & Lombardini 2004)

Exogenous taurine administration may be helpful in preventing age related changes in the retina.(Militante & Lombardini 2004)

Taurine concentrations seem to be markedly decreased in injured photoreceptors of dogs with glaucoma.(Madl et al. 2005)

Taurine transformed rat retinal ganglia are protected from hypoxia-induced apoptosis, probably through the prevention of mitochondrial dysfunction.(Chen et al. 2009).

One report in a small number of rabbits suggested that when topically applied 0.5% timolol was mixed with several amino acids, including taurine, the IOP decrease in the rabbit eye was greater than with timolol alone. (Olah & Veselovsky 2007)

References

Altshuler D, JJ Lo Turco, J Rush & C Cepko (1993): Taurine promotes the differentiation of a vertebrate retinal cell type in vitro. Development 119: 1317-28.

Chen K, Q Zhang, J Wang, F Liu, M Mi, H Xu, F Chen & K Zeng (2009): Taurine protects transformed rat retinal ganglion cells from hypoxia-induced apoptosis by preventing mitochondrial dysfunction. Brain Res 1279: 131-8.

Eppler B & R Dawson, Jr. (2001): Dietary taurine manipulations in aged male Fischer 344 rat tissue: taurine concentration, taurine biosynthesis, and oxidative markers. Biochem Pharmacol 62: 29-39.

Huxtable RJ & LA Sebring (1986): Towards a unifying theory for the actions of taurine. TIPS 7: 481-485.

Kim C & YN Cha (2009): Production of reactive oxygen and nitrogen species in phagocytes is regulated by taurine chloramine. Adv Exp Med Biol 643: 463-72.

Madl JE, TR McIlnay, CC Powell & JR Gionfriddo (2005): Depletion of taurine and glutamate from damaged photoreceptors in the retinas of dogs with primary glaucoma. Am J Vet Res 66: 791-9.

Militante J & JB Lombardini (2004): Age-related retinal degeneration in animal models of aging: possible involvement of taurine deficiency and oxidative stress. Neurochem Res 29: 151-60.

Militante J & JB Lombardini (2004): Age-related retinal degeneration in animal models of aging: possible involvement of taurine deficiency and oxidative stress. Neurochem Res 29: 151-60.

Olah Z & J Veselovsky (2007): Rabbit's intraocular pressure after instillation of timolol and aminoacid lysine, arginine, glycine or taurine mixture. Bratisl Lek Listy 108: 283-6.

Schuller-Levis GB & E Park (2004): Taurine and its chloramine: modulators of immunity. Neurochem Res 29: 117-26.

Sturman JA (1986): Nutritional taurine and central nervous system development. Ann N Y Acad Sci 477: 196-213.

Tohgi H, S Takahashi & T Abe (1993): The effect of age on concentrations of monoamines, amino acids, and their related substances in the cerebrospinal fluid. J Neural Transm Park Dis Dement Sect 5: 215-26.

Wallace DR & R Dawson, Jr. (1990): Decreased plasma taurine in aged rats. Gerontology 36: 19-27.

Young TL & CL Cepko (2004): A role for ligand-gated ion channels in rod photoreceptor development. Neuron 41: 867-79.