ASCORBIC-ACID PROTECTS AGAINST LEVODOPA-INDUCED NEUROTOXICITY ON A CATECHOLAMINE-RICH HUMAN NEUROBLASTOMA CELL-LINE

Levodopa, at concentrations of 0.25 x 10(-4) m or larger, is toxic for the human neuroblastoma cell NB69. Toxicity is associated with high l evels of quinones, increased activity of complex II-III, and lack Of c hanges of complex I of the mitochondrial respiratory chain. Deprenyl, which does not alter the production of quinones, has a partial protect ive effect. TocoPherol, 23 or 115 X 10(-6) M, lacks significant Preven tive effect on levodopa toxicity, but ascorbiC acid, 10(-3) M, prevent s levodopa toxicity and quinone formation. Deprenyl, 10(-4) M, proVide S additional protection in cultures treated with levodoPa and ascorbic acid. Our results indicate that ascorbic acid and deprenyl prevent le vodopa neurotoxicity by unrelated mechanisms. Both comPounds should be considered as complementary drugs to test for slowing the progression of Parkinson's disease.