Mitochondria are the source of hydrogen peroxide for dynamic brain-cell signaling.
Hydrogen peroxide (H(2)O(2)) is emerging as a ubiquitous small-molecule messenger in biology, particularly in the brain, but underlying mechanisms of peroxide signaling remain an open frontier for study. For example, dynamic dopamine transmission in dorsolateral striatum is regulated on a subsecond timescale by glutamate via H(2)O(2) signaling, which activates ATP-sensitive potassium (K(ATP)) channels to inhibit dopamine release. However, the origin of this modulatory H(2)O(2) has been elusive. Here we addressed three possible sources of H(2)O(2) produced for rapid neuronal signaling in striatum: mitochondrial respiration, monoamine oxidase (MAO), and NADPH oxidase (Nox). Evoked dopamine release in guinea-pig striatal slices was monitored with carbon-fiber microelectrodes and fast-scan cyclic voltammetry. Using direct fluorescence imaging of H(2)O(2) and tissue analysis of ATP, we found that coapplication of rotenone (50 nM), a mitochondrial complex I inhibitor, and succinate (5 mM), a complex II substrate, limited H(2)O(2) production, but maintained tissue ATP content. Strikingly, coapplication of rotenone and succinate also prevented glutamate-dependent regulation of dopamine release, implicating mitochondrial H(2)O(2) in release modulation. In contrast, inhibitors of MAO or Nox had no effect on dopamine release, suggesting a limited role for these metabolic enzymes in rapid H(2)O(2) production in the striatum. These data provide the first demonstration that respiring mitochondria are the primary source of H(2)O(2) generation for dynamic neuronal signaling.
Bao
Li
L
Department of Neurosurgery, New York University School of Medicine, New York, New York 10016, USA.
Avshalumov
Marat V
MV
Patel
Jyoti C
JC
Lee
Christian R
CR
Miller
Evan W
EW
Chang
Christopher J
CJ
Rice
Margaret E
ME
D000255:Adenosine Triphosphate / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000166:cytology*; D004298:Dopamine / Q000032:analysis; D004347:Drug Interactions; D004558:Electric Stimulation / Q000379:methods; D004563:Electrochemistry / Q000379:methods; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D006168:Guinea Pigs; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007004:Hypoglycemic Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000648:ultrastructure*; D012402:Rotenone / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D019802:Succinic Acid / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D007004:Hypoglycemic Agents; D009419:Nerve Tissue Proteins; D026941:Sodium Channel Blockers; D012402:Rotenone; D018698:Glutamic Acid; D013779:Tetrodotoxin; D000255:Adenosine Triphosphate; D019802:Succinic Acid; D006861:Hydrogen Peroxide; D005905:Glyburide; D004298:Dopamine