Protection Against Peroxidation by Radicals in Cerebral Capillaries and Microvessels During Aging
Nerve tissue (like cerebral capillaries and microvessels) has a high concentration of polyunsaturated fatty acids of the linoleic and alpha-linolenic series. It also consumes large amounts of oxygen. Peroxidation of these fatty acids due to free radicals is a substantial risk for the biochemistry and physiology of these membranes and can result in cellular death.
Systemic injection in the rat of substances that generate free radicals seriously alters various tissues (as shown by the production of conjugated dienes and malondialdehyde) but has only a slight effect on the brain. This shows that the blood-brain barrier confers considerable protection. In fact cerebral capillaries and microvessels show superoxide dismutase, glutathione peroxidase, and catalase activities that are higher than those in the rest of cerebral tissues during aging.These activities vary little, except for catalase, which decreases. Curiously, the concentrations of Mn, Cu, and Zn are not related to the enzyme activities, whereas these trace elements are necessary for the activities of superoxide dismutase. On the other hand, during aging the cerebral capillaries and microvessels undergo pronounced changes at the level of the polyunsaturated fatty acids: for example, the concentration of arachidonic acid (expressed as a percentage) decreases by half.
KeywordsArachidonic Acid Superoxide Dismutase Polyunsaturated Fatty Acid Glutathione Peroxidase Glutathione Reductase
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