L-dopa cytotoxicity to PC12 cells in culture is via its autoxidation

J Neurochem. 1995 Feb;64(2):825-32. doi: 10.1046/j.1471-4159.1995.64020825.x.


The mechanism of cytotoxicity of L-DOPA was studied in the rat pheochromocytoma PC12 cell line. The cytotoxicity of L-DOPA to PC12 cells was time and concentration dependent. Carbidopa, which inhibited the conversion of L-DOPA to dopamine, did not protect against L-DOPA cytotoxicity in PC12 cells. Furthermore, clorgyline, a selective inhibitor of monoamine oxidase type A, and pargyline, an inhibitor of both monoamine oxidase types A and B, both did not have an effect on L-DOPA toxicity. These findings suggest that cytotoxicity was not due to dopamine formed from L-DOPA. Catalase or superoxide dismutase each partially protected against L-DOPA toxicity in PC12 cells. In combination, the effects were synergistic and provided almost total protection against cytotoxicity. 6-Cyano-7-nitroquinoxaline-2,3-dione, an antagonist of non-NMDA receptors, did not protect against L-DOPA toxicity. These data suggest that toxicity of L-DOPA is most likely due to the action of free radicals formed as a result of its autoxidation. Furthermore, these findings suggest that patients on long-term L-DOPA therapy are potentially at risk from the toxic intermediates formed as a result of its autoxidation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Catalase / pharmacology
  • Cell Survival / drug effects
  • Dopamine / metabolism
  • Levodopa / antagonists & inhibitors
  • Levodopa / metabolism*
  • Levodopa / pharmacology*
  • Oxidation-Reduction
  • PC12 Cells
  • Rats
  • Receptors, Amino Acid / physiology
  • Superoxide Dismutase / pharmacology


  • Receptors, Amino Acid
  • Levodopa
  • Catalase
  • Superoxide Dismutase
  • Dopamine