“…In addition to enzymatic antioxidant defenses, cells possess low-molecular-weight, free radical scavengers such as vitamin E, reduced glutathione, cysteine, 0-carotene, and ascorbic acid (Fridovich, 1978) to decrease the content of free radical species (Tappel, 1973). Free radicals probably are involved in the inactivation of some enzymes (Lin and Armstrong, 1978;Kono and Fridovich, 1982), in the impairment of synthesis and metabolism of nucleic acids due to single-and double-strand DNA breaks (for review see Giuffrida-Stella and Lajtha, 1987), degradation of hyaluronic acid (McCord, 1984), and increased vascular permeability (Johnson et al,198 1). Cerebral mitochondria, particularly the intrasynaptic ones, represent a potent source of oxygen-free radicals, which are produced at the level of ubiquinonecytochrome b and NADH dehydrogenase complexes (Freeman and Crapo, 1982).…”