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Mitochondria are a major source of paraquat-induced reactive oxygen species production in the brain

Pablo R Castello1, Derek A Drechsel, Manisha Patel

  • 1Department of Pharmaceutical Sciences, University of Colorado at Denver and Health Sciences Center, Denver, CO 80262, USA.

The Journal of Biological Chemistry
|March 29, 2007
PubMed

Insights

Brain mitochondria are a key source of reactive oxygen species (ROS) production induced by the toxin paraquat (PQ(2+)). This process involves the mitochondrial electron transport chain and depends on the inner transmembrane potential.

Area of Science:

  • Neuroscience
  • Toxicology
  • Cell Biology

Background:

  • Paraquat (PQ(2+)) is a known toxin that causes injury via oxidative stress.
  • PQ(2+) shares structural similarities with 1-methyl-4-pheynlpyridinium, a toxicant linked to Parkinson's disease.
  • The specific cellular origins of PQ(2+)-induced reactive oxygen species (ROS) in neuronal tissues are not fully understood.

Purpose of the Study:

  • To investigate the role of brain mitochondria in paraquat-induced ROS production.
  • To identify the cellular mechanisms underlying paraquat's oxidative effects in the brain.

Main Methods:

  • Purification of rat brain mitochondria using Percoll density gradient centrifugation.
  • Measurement of paraquat-induced hydrogen peroxide (H(2)O(2)) production using fluorometric and polarographic techniques.
  • Assessment of H(2)O(2) production in the presence of mitochondrial respiratory chain modulators and substrates.
  • Confirmation of findings in primary midbrain neuronal cells.

Main Results:

  • Mitochondria are identified as a primary site of paraquat-induced H(2)O(2) production in the rat brain.
  • Paraquat-induced H(2)O(2) production is dependent on the availability of respiratory substrates.
  • Complex III of the mitochondrial electron transport chain plays a crucial role in paraquat-induced H(2)O(2) generation.
  • The mechanism of paraquat-induced H(2)O(2) production is linked to the mitochondrial inner transmembrane potential.

Conclusions:

  • Brain mitochondria are a significant source of ROS generated by paraquat.
  • The electron transport chain, particularly complex III, is central to paraquat's oxidative effects in mitochondria.
  • These findings elucidate a mechanism by which mitochondria contribute to ROS production by redox-cycling agents implicated in Parkinson's disease.

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