AMINOGUANIDINE INHIBITS REACTIVE OXYGEN SPECIES FORMATION, LIPID-PEROXIDATION, AND OXIDANT-INDUCED APOPTOSIS

Aminoguanidine (AG) treatment, like nerve growth factor (NGF) treatmen t, prevents diabetes-induced apoptosis of retinal Muller cells in the rat eye, but the mechanism involved is unknown. In this study, the eff ects of preincubation with AG on oxidant-induced apoptosis, oxidant-in duced intracellular reactive oxygen species (ROS) production, and lipi d peroxidation were determined in rat retinal Muller cells and compare d with the effects of NGF, a protein that protects neuronal cells from oxidative stress. The effect of AG on rabbit vitreous lipid peroxide levels was also determined. After exposure to increasing concentration s of H2O2, there was a corresponding increase in the percentage of apo ptotic Muller cells. Preincubation with AG for 48 h completely inhibit ed oxidant-induced apoptosis in response to 10 mu mol/l H2O2 (+AG 0 vs . 10 mu mol/l, NS), and reduced the percentage of apoptotic cells in r esponse to 50 mu mol/l H2O2 by 50% (+ AG vs. -AG, P < 0.01). Longer pr eincubation did not increase the anti-apoptotic effect of AG. The effe ct of AG was dose-dependent. Similar results were obtained after prein cubation with NGF. Both AG and NGF preincubation prevented the twofold increase in oxidant-induced lipid peroxides. The fivefold increase in oxidant-induced ROS production was decreased 100% by NGF, but only 61 % by AG preincubation. The twofold increase in vitreous lipid peroxide level in diabetic rabbits was completely prevented by AG treatment. A G reduced H2O2-induced benzoate hydroxylation in a dose-dependent mann er. Intracellular glutathione content was unchanged. These data demons trate that AG can act as an antioxidant in vivo, quenching hydroxyl ra dicals and lipid peroxidation in cells and tissues and preventing oxid ant-induced apoptosis.