Autoxidation of rat brain homogenate: evidence for spontaneous lipid peroxidation. Comparison with the characteristics of Fe2+- and ascorbic acid-stimulated lipid peroxidation.
Aerobically-incubated brain homogenates are known to undergo autoxidation characterized by spontaneous TBARS production, presumably as a result of lipid peroxidation. However, TBARS measurement alone, because of its lack of specificity, is not sufficient to demonstrate the occurrence of lipid peroxidation in complex biological systems. This study, undertaken to determine whether or not spontaneous oxidation of rat brain homogenate is due to lipid peroxidation, measured different specific markers of this process (fatty acids, lipid aldehydes and the formation of fluorescence products) and studied changes in alpha-tocopherol. Incubation of rat brain homogenates at 37 degrees C under air led to spontaneous TBARS formation, which was accompanied by lipid aldehydes and lipid fluorescence products as well as polyunsaturated fatty acid (PUFA) degradation. Alpha-tocopherol was also consumed. On the whole, these results demonstrate that autoxidation of brain homogenate is a spontaneous lipid peroxidation process. When homogenates were exposed to Fe2+ and ascorbic acid-induced oxidative stress, lipid peroxidation was enhanced. However, spontaneous and stimulated peroxidation showed similar patterns not characteristic of classical lipid peroxidation, i.e. without the lag and accelerating phases typical of a propagating chain reaction. PUFA degradation was limited despite stimulation of peroxidation.
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Laboratoire de Biochimie et Toxicologie, Hôpital Jean Bernard, Poitiers, France.
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D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology*; D015415:Biomarkers; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D005227:Fatty Acids / Q000302:isolation & purification / Q000378:metabolism; D005453:Fluorescence; D007501:Iron / Q000494:pharmacology*; D050356:Lipid Metabolism; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014810:Vitamin E / Q000378:metabolism
D015415:Biomarkers; D005227:Fatty Acids; D017392:Thiobarbituric Acid Reactive Substances; D014810:Vitamin E; D007501:Iron; D001205:Ascorbic Acid