Hyperprolinemia induces DNA, protein and lipid damage in blood of rats: antioxidant protection.

The present study investigated the effects of hyperprolinemia on oxidative damage to biomolecules (protein, lipids and DNA) and the antioxidant status in blood of rats. The influence of the antioxidants on the effects elicited by proline was also examined. Wistar rats received two daily injections of proline and/or vitamin E plus C (6th-28th day of life) and were killed 12h after the last injection. Results showed that hyperprolinemia induced a significant oxidative damage to proteins, lipids and DNA demonstrated by increased carbonyl content, malondialdehyde levels and a greater damage index in comet assay, respectively. The concomitant antioxidants administration to proline treatment completely prevented oxidative damage to proteins, but partially prevented lipids and DNA damage. We also observed that the non-enzymatic antioxidant potential was decreased by proline treatment and partially prevented by antioxidant supplementation. The plasma levels of vitamins E and C significantly increased in rats treated exogenously with these vitamins but, interestingly, when proline was administered concomitantly with vitamin E plus C, the levels of these vitamins were similar to those found in plasma of control and proline rats. Our findings suggest that hyperprolinemia promotes oxidative damage to the three major classes of macromolecules in blood of rats. These effects were accomplished by decrease in non-enzymatic antioxidant potential and decrease in vitamins administered exogenously, which significantly decreased oxidative damage to biomolecules studied. These data suggest that antioxidants may be an effective adjuvant therapeutic to limit oxidative damage caused by proline.

Homocysteine alters glutamate uptake and Na+,K+-ATPase activity and oxidative status in rats hippocampus: protection by vitamin C.

In the present study we investigate the effect of homocysteine on glutamate uptake, Na+,K+-ATPase, enzymatic antioxidant defenses, as well as reactive species levels in hippocampus of rats. The influence of vitamin C, a classic antioxidant, on the effects elicited by homocysteine was also tested. Results showed that chronic hyperhomocysteinemia decreased glutamate uptake and the activities of Na+,K+-ATPase, catalase and superoxide dismutase in hippocampus of rats. Reactive species levels were increased by chronic homocysteine administration. Concomitant administration of vitamin C significantly prevented these alterations caused by homocysteine. According to our results, it seems possible to suggest that the reduction in glutamate uptake and Na+,K+-ATPase activity may be mediated by oxidative stress, since vitamin C prevented these effects. We suggest that the administration of antioxidants should be considered as an adjuvant therapy to specific diet in homocystinuria.