[Free radicals and degenerative diseases of the nervous system]

Degenerative diseases of the nervous system which are considered to be related to free radicals are Parkinson's disease and Alzheimer-type dementia (ATD). Parkinson's disease is characterized by appearance of Leyw's body and degeneration of nigrostriatal dopaminergic system. But the most fundamental cause of this disease remains still unknown. The fact that H2O2 is formed in the process of oxidative deamination of catecholamines and some substances which can cause Parkinsonism in animal experiments also produce active oxygen in the metabolic processes suggest the important role of free radicals in the pathogenesis of Parkinson's disease. We recently observed that addition of DOPA and Fe3(+)-ADP complex to the microsomal phospholipid system produced lipid peroxides without participation of active oxygen. Neurons cultured in vitro also decreased significantly with addition of DOPA and Fe3(+)-ADP complex and this harmful effect was prevented by desferoxamine (potent Fe chelating agent) or alpha-tocopherol (antioxidant). These results may suggest that lipid peroxidation can occur by interaction of naturally existing substances in the dopaminergic system and induce cell damage. As regards ATD, there is still no definite evidence to support the implication of free radicals in its pathogenesis. However, there are reports that lipid peroxides increase significantly in the brains of patients with ATD. Moreover, recent advances in the study of amyloid in the senile plaque revealed close relationship of ATD to chromosome 21.(ABSTRACT TRUNCATED AT 250 WORDS)