By Joseph Knoll

Type-A monoamine oxidase (MAO-A) is the form of monoamine oxidase (MAO) that is sensitive to clorgyline. Clorgyline, 3-(2, 4-dichlorophenoxy)-N-methyl-N-2-ynylpropan-1-amine, is an irreversible MAO inhibitor substance, structurally related to pargyline. This term was coined and introduced, in 1968, by Johnston, to distinguish between clorgyline-sensitive and insensitive forms of monoamine oxidase (MAO) enzymes that,he referred to as Type-A monoamine oxidase and Type-B monoamine oxidase, respectively. MAO-A was found to be present in the neurons, astroglia, gastrointestinal tract, liver and placenta (Neff and Gorodis 1972). By the early 1970, it was recognized that MAO-A is primarily responsible for the oxidative deamination of the monoamines serotonin, melatonin, noradrenaline (norepinephrine) and adrenaline (epinephrine), and not only of serotonin, as originally preoposed (Costa and Sandler 1972).

Costa E, Sandler M (editors). Monoamine Oxidases – New Vistas. Advances in Biochemical Psychopharmacology. Volume 5. New York:  Raven Press; 1972.

Johnston JP. Some observations upon a new inhibitor of monoamine oxidase in human brain. Biochemicl Pharmacology 1968; 17: 1285-1297.  

Neff NH, Gorodis C. Neuronal monoamine oxidase: specifi types and their rates of formation. Advances Biochemical Psychopharmacology 1972; 5: 2017-23, 

Joseph Knoll

August 14, 2014