Abstract
In a previous study, we showed evidence that oxidative stress induced by hydrogen peroxide (H2O2) can inhibit the release of [ 3H]-D-aspartate from the bovine isolated retina, in vitro. The aim of the present study was to investigate the effect of H2O 2 on glutamate and glycine levels in the bovine retina and vitreous humor, ex vivo. Furthermore, we examined whether inhibition of catalase activity with 3-amino-triazole had any effect on the concentrations of these amino acids in the posterior segment of the bovine eye. Whole eye organ cultures were prepared by incubating tissues in oxygenated Krebs solution at 37 °C for 30 min. After incubation, H2O2 (1-100 μM) or sterile distilled water was injected intravitreally into each eye. Thirty minutes after injection, the retina and vitreous humor were removed for analysis of glutamate and glycine by high performance liquid chromatography (HPLC) with fluorescence detection. Exogenously applied H2O 2 (1-100 μM) caused a concentration-related decrease in both glutamate and glycine levels in the bovine retina. Furthermore, while H 2O2 (1-10 μM) caused a concentration-dependent decrease in glycine levels in the vitreous humor, it had no significant effect on glutamate levels. The catalase inhibitor, 3-amino-triazole (10 mM), caused a significant reduction in both glutamate and glycine levels in the bovine retina, ex vivo. Likewise, 3-AT caused an attenuation in both glutamate and glycine concentration in the vitreous humor. We conclude that oxidative stress induced by H2O2 can alter the release and/or availability of amino acids in the posterior segment of bovine eyes.