A subpopulation of mouse striatal cholinergic neurons show monoamine oxidase activity.

We examined the histochemical localization of monoamine oxidase (MAO) in the mouse striatum. MAO activity was observed in glial cells and vessels in accordance with previous reports in the rat brain. In addition to these previously documented structures, we found MAO-containing neurons in the mouse striatum. Enzyme inhibition experiments showed that MAO in the positive neurons was predominantly of type B. Double-labeling studies showed that in this region these neurons were cholinergic. The functional role of MAO activity in the mouse striatal cholinergic neurons is presently unclear.