Localization of monoamine oxidases in human peripheral tissues

Abstract

Localization of monoamine oxidases (MAO) A and B and beta-adrenoceptors, was studied in aged human peripheral tissues (age 68-80 years) by quantitative autoradiography. The tissues analyzed were heart, lung, liver, kidney, spleen and duodenum. [3H]Ro41-1049 and [3H]lazabemide, two recently characterized selective radioligands were used to map MAO-A and MAO-B respectively. The regional pattern of distribution of MAO-A and MAO-B did not differ markedly, except in kidney and especially in duodenum. Highest levels of MAOs were measured in liver, and lowest in spleen. MAO-A was more abundant than MAO-B in lung and duodenal mucosa, and the reverse was true in myocardium. These results show marked differences in the abundance and patterns of distribution of MAOs, particularly MAO-B, in human and rodent peripheral tissues.