Glutathione elevation and its protective role in acrolein-induced protein damage in synaptosomal membranes: relevance to brain lipid peroxidation in neurodegenerative disease

Oxidative stress may be a hallmark of several neurodegenerative disorders, including Alzheimer's disease (AD) Huntington's, and Parkinson's diseases a s well as amyotrophic lateral sclerosis. Acrolein is a highly reactive prod uct of lipid peroxidation that is elevated in the brains of persons with AD . This alkenal potentially can react with proteins by Michael addition to a lter their structure and function. In the present study, we used electron p aramagnetic resonance in conjunction with a protein-specific spin label to monitor synaptosomal membrane protein conformational alterations induced by acrolein. A dose-dependent increased conformational alteration was observe d. Consistent with this finding, protein carbonyl levels from protein-bound acrolein were significantly elevated. However, pretreatment of synaptosome s with glutathione ethyl ester (GEE) significantly ameliorated both the con formational alterations and protein carbonyls induced by acrolein. Based on this success, we tested the hypothesis that elevated levels of endogenous glutathione (GSH) would offer protection against acrolein-induced oxidative stress. In-vivo elevation of GSH (215% over control, P < 0.04) was produce d by i.p. injection of N-acetyleysteine (NAC), a known precursor of GSH. Sy naptosomes were treated with vehicle or 2 nM acrolein, the level of this al kenal found in AD brain. In contrast to synaptosomes from control animals, which had significantly increased protein carbonyl levels following additio n of 2 nM acrolein, synaptosomes that were isolated from NAC-treated rodent s and treated with 2 nM acrolein showed no increased carbonyl levels compar ed to untreated controls. These results demonstrate protection by increased in-vivo GSH levels against acrolein-induced oxidative stress at levels fou nd in AD brain and are consistent with the notion that methods to increase endogenous GSH levels in neurodegenerative diseases associated with oxidati ve stress may be promising. (C) 2001 Elsevier Science Ltd. All rights reser ved.