Immunocytochemical localization of monoamine oxidases A and B in human peripheral tissues and brain.
Monoamine oxidases (MAO; EC 1.4.3.4.) A and B occur in the outer mitochondrial membrane and oxidize a number of important biogenic and xenobiotic amines. Monoclonal antibodies specific for human MAO A or B and immunocytochemical techniques were used to visualize the respective enzymes in human placenta, platelets, lymphocytes, liver, brain, and a human hepatoma cell line. MAO A was observed in the syncytiotrophoblast layer of term placenta, liver, and a subset of neurons in brain, but was not observed in platelets or lymphocytes, which are known to lack type A enzyme. MAO B was observed in platelets, lymphocytes, and liver, but not in placenta, which contains little or no MAO B. MAO B was also observed in a subset of neurons in the brain that was distinct from that which contained MAO A. MAO A and MAO B were also observed in some glia. Unlike most tissues examined, liver cells appeared to contain both forms of the enzyme. These studies show that MAO A and MAO B can be specifically visualized by immunocytochemical means in a variety of human cells and tissues and can provide a graphic demonstration of the high degree of cell specificity of expression of the two forms of the enzyme.
D000911:Antibodies, Monoclonal; D001792:Blood Platelets / Q000201:enzymology; D001921:Brain / Q000201:enzymology*; D006528:Carcinoma, Hepatocellular / Q000201:enzymology; D002460:Cell Line; D005260:Female; D006651:Histocytochemistry; D006801:Humans; D007120:Immunochemistry; D008099:Liver / Q000201:enzymology; D008113:Liver Neoplasms; D008214:Lymphocytes / Q000201:enzymology; D008995:Monoamine Oxidase / Q000032:analysis* / Q000276:immunology; D010920:Placenta / Q000201:enzymology
D000911:Antibodies, Monoclonal; D008995:Monoamine Oxidase