Pharmacology and physiology of monoamine oxidase activity in vertebrates--a comparative study

Monoamine oxidase (MAO) activity is high in brain, where it regulates neurotransmitter levels, and in the 'detoxifying' organs. Two MAO isoenzymes (A and B) apparently exist in terrestrial tetrapods, but only one form (type A-like) can be detected in teleosts and in aquatic amphibia. MAO activity is regulated by both endogenous (hormones, substrates) and exogenous (daylength, temperature) factors.