Methinks excess dopamine in the brain can get metabolized directly by MAO into DOPAL which, if ALDH2 is busy, can cause superoxide formation and cell death. "B

Methinks excess dopamine in the brain can get metabolized directly by MAO into DOPAL which, if ALDH2 is busy, can cause superoxide formation and cell death. "Both the accumulation of DOPAL and the enhancement of rotenone-induced toxicity were abrogated by inhibiting the formation of DOPAL with the MAO inhibitor, clorgyline. These observations suggest that the MAO-catalyzed formation of DOPAL and its accumulation by various mechanisms may be important processes that aggravate the neurotoxicity associated with mitochondrial dysfunction." http://pharmrev.aspetjournals.org/content/59/2/125.full http://pharmrev.aspetjournals.org/content/59/2/125.full So this is why MAO inhibitors are neuroprotective. They prevent this reaction.