Monoamine oxidase (MAO) is an enzyme that utilizes oxidative deamination to catalyze the breakdown, or metabolism, reactions of various monoamine neurotransmitters such as the catecholamines (norepinephrine, epinephrine, and dopamine) and the indoleamines (serotonin and melatonin) to inactive products. Monoamine oxidase is the target for a class of antidepressants known as the monoamine oxidase inhibitors (MAOIs), which include phenelzine, tranylcypromine, and selegiline as the more popular agents of the class. The MAOIs were the first clinically effective antidepressants. There are two subtypes of MAO, type A (MAO-A) and type B (MAO-B). Whereas MAO-A is responsible for metabolizing norepinephrine, dopamine, and serotonin, MAO-B is more selective for dopamine. Therefore, the inhibition of MAO-A is necessary for antidepressant effects.
However, tyramine, a naturally occurring compound found in aged meats, cheeses, and some other foods, is a potent releaser of norepinephrine,...
References and Readings
- Brunton, L. L., Chabner, B. A., & Knollman, B. C. (Eds.). (2011). Goodman & Gilman’s the pharmacological basis of therapeutics (12th ed.). New York: McGraw-Hill.Google Scholar
- Cooper, J. R., Bloom, F. E., & Roth, R. H. (Eds.). (2003). The biochemical basis of neuropharmacology (8th ed.). New York: Oxford University Press.Google Scholar
- Davis, K. L., Charney, D., Coyle, J. T., & Nermeroff, C. (Eds.). (2002). Neuropsychopharmacology: The fifth generation of progress. Philadelphia: Lippincott Williams & Wilkins.Google Scholar
- Stahl, S. M. (2013). Stahl’s essential psychopharmacology: Neuroscientific basis and practical applications (4th ed.). New York: Cambridge University Press.Google Scholar
- Voet, D., Voet, J. G., & Pratt, C. W. (Eds.). (2016). Fundamentals of biochemistry: Life at the molecular level (5th ed.). New Jersey: Wiley.Google Scholar