Electron-microscopic study of MAOB-containing structures in the nucleus accumbens shell: using MAOA-deficient transgenic mice

Abstract MAOB-containing structures in the nucleus accumbens were ultrastructurally studied for the first time, using MAOA-deficient transgenic mice and MAO enzyme histochemistry. Among the striatal structures, the nucleus accumbens, and in particular its dorsal shell, showed the strongest MAOB activity. MAOB-active cell bodies were embedded in a dense MAOB-active fiber plexus. MAOB-positive terminals formed axo-dendritic synapses which were exclusively of the asymmetric type. It is suggested that dopamine in the nucleus accumbens shell is transported into MAOB-positive fibers where it is degraded by MAOB.