6-Hydroxydopamine induces mitochondrial ERK activation

Scott M. Kulich*, Craig Horbinski, Manisha Patel, Charleen T. Chu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Reactive oxygen species (ROS) are implicated in 6-hydroxydopamine (6-OHDA) injury to catecholaminergic neurons; however, the mechanism(s) are unclear. In addition to ROS generated during autoxidation, 6-OHDA may initiate secondary cellular sources of ROS that contribute to toxicity. Using a neuronal cell line, we found that catalytic metalloporphyrin antioxidants conferred protection if added 1 h after exposure to 6-OHDA, whereas the hydrogen peroxide scavenger catalase failed to protect if added more than 15 min after 6-OHDA. There was a temporal correspondence between loss of protection and loss of the ability of the antioxidant to inhibit 6-OHDA-induced ERK phosphorylation. Time course studies of aconitase inactivation, an indicator of intracellular superoxide, and MitoSOX red, a mitochondria targeted ROS indicator, demonstrate early intracellular ROS followed by a delayed phase of mitochondrial ROS production, associated with phosphorylation of a mitochondrial pool of ERK. Furthermore, on initiation of mitochondrial ROS and ERK activation, 6-OHDA-injured cells became refractory to rescue by metalloporphyrin antioxidants. Together with previous studies showing that inhibition of the ERK pathway confers protection from 6-OHDA toxicity, and that phosphorylated ERK accumulates in mitochondria of degenerating human Parkinson's disease neurons, these studies implicate mitochondrial ERK activation in Parkinsonian oxidative neuronal injury.

Original languageEnglish (US)
Pages (from-to)372-383
Number of pages12
JournalFree Radical Biology and Medicine
Issue number3
StatePublished - Aug 1 2007


  • 6-Hydroxydopamine
  • Extracellular signal-regulated MAP kinases
  • Mitochondria
  • Parkinson's disease
  • Reactive oxygen species

ASJC Scopus subject areas

  • Physiology (medical)
  • Biochemistry


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