Since the brain contains a large amount of polyunsaturated fatty acids, consumes up to 20% of oxygen used by the whole body and exhibits low antioxidants activity, it seems to be especially vulnerable to oxidative stress.
The most important antioxidant enzymes are superoxide dismutase (SOD), which catalyze the dismutation of superoxide anion to hydrogen peroxide, catalase (CAT), which converts toxic hydrogen peroxide to water and oxygen, and glutathione peroxidase (Se-GSHPx), which reduces hydrogen peroxide and organic peroxides with glutathione as the cofactor. Among other detoxifying enzymes, the most significant is glutathione transferase (GST), which shows detoksyvarious
catalytic activities allowing for removal of xenobiotics, reducing organic peroxides
and oxidized cell components. One of the most important brain nonenzymatic antioxidants
is reduced glutathione (GSH), which (individually or in cooperation with peroxidases) participates
in the reduction of free radicals, repair of oxidative damage and the regeneration of
other antioxidants, such as ascorbate or tocopherol. Glutathione as a cosubstrate of glutathione
transferase scavenges toxic electrophilic compounds.
Although the etiology of the major neurodegenerative diseases are unknown, numerous data
suggest that reactive oxygen species play an important role.
Even a small change in the level of antioxidants can leads to the many disorders in the CNS.
Effect of whole body x-radiation and of intraperitoneal hydrogen peroxide on a nucleoprotein fraction of rat intestine and on whole rat intestine