OXIDATIVE DAMAGE TO PROTEINS AND LIPIDS OF CNS MYELIN PRODUCED BY IN-VITRO GENERATED REACTIVE OXYGEN SPECIES

Purified myelin isolated from 70-day-old rats was submitted to nonenzy matic peroxidative systems containing 100 mu M FeCl3.6H(2)O, 100 mu M ascorbic acid, and 100 mu M CuSO4.6H(2)O 10 mM H2O2 in order to invest igate the extent of damage produced by reactive oxygen species (ROS), Iron and copper catalyzing systems were selected because of the known importance of these metals in producing free radical chain reactions i n biological membranes (Halliwell and Gutteridge: ''Free Radicals in B iology and Medicine,'' Oxford: Clarendon Press, 1989). Our findings sh ow that: (1) although after 1 hour of peroxidation, an important level of thiobarbituric acid-reactive substances (TEARS) was detected, poly unsaturated fatty acids (20:2; 20:4; 22:4 and 22:6) were markedly affe cted only after 14 hours of incubation; (2) protein thiol groups were very sensitive to the attack of ROS generated by copper but resistant to iron-generated ROS; (3) aggregation of myelin proteins produced by peroxidation could be prevented by sulfhydryl (SH)-reducing agents, an d (4) as a consequence of these modifications, compact myelin suffered disruption of its intraperiodic line, In conclusion, our results demo nstrate that this unique membrane of the central nervous system (CNS) is highly vulnerable to oxidative stress and that this susceptibility to oxidative damage could be prevented, at least partially, by the use of SH-protective molecules. (C) 1995 Wiley-Liss, Inc.