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A.M. Petrosian, J.E. Haroutounian, L.A. Poghosyan, R.V. Stepanyan, H.V. Topchyan; Measurements of Taurine, Tauret, and Neuroactive Amino Acids in the Rat Retina Under Dark and Light Adaptation . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5145.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To measure taurine, glutamate, aspartate, glycine as well as retinyliden taurine–tauret, newly discovered endogenous conjugate (see US Patent No 6,391,924 B1), in wild white rat retina under dark–light adaptation and after mild light induced damage.Methods: Amino acids were measured in 0.1N HClO4 extracts of fresh dark or light and mild damaged retinae by HPLC. Tauret was determined in 100 % methanol extracts of freeze dried dark or light rat retina by TLC in combination with spectral measurements.Results: This series represents measurements of 6 determinations in mM with p < 0.1 Taurine level was 3.41+ –0.47, remarkably high in dark rat retina compared with glutamate 1.6.+ –0.27, aspartate 1.06+ –0.23 and glycine 0.51+ –0.09. Pilot TLC measurements showed the most high level of taurine in rat retina compared with heart, spleen, muscle, liver and brain tissue. Light adaptation (500 lx/3hr) causes noticeable decrease of amino acids level in the retina. Taurine decreased to 2.56+ –0.26, glutamate to 1.43.+ –0.19, aspartate to 0.75+ –0.12. Only glicine increased to 0.53+ –0.09. After mild light induced damage (5000 lx/3hr) taurine level in retina becomes lower – 2.09±074, while glutamate raises to 1.77+ –0.16, aspartate – 0.92+ –0.18 and glycine 0.56+ –0.08. Tauret level was in micro molar range in dark retina and was several times higher compared with retina illuminated by 500 lx/3hr.Conclusions: These results indicate that free amino acids content in retina is very sensitive to light conditions and probably taurine may play two different roles in photoreceptor cells and in inner retina. Particularly via tauret, probably taurine nearby with specific retinoid binding proteins can play an essential role in 11–cis and all–trans retinoid transport and thus can be involved in rhodopsin regeneration and prevention from light induced damage of photoreceptor cells.
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