Studies on brain metabolism of biogenic amines.

1. In vitro models (synaptosones, electrically stimulated brain slices and monoamine oxidase (MAO) preparations have been used to identify the sites of action of nomifensine on brain monoamine metabolism. 2. Nomifensine potentiates neurotransmission in noradrenergic and dopaminergic synapses by blocking catecholamine uptake. 3. Nomifensine does not inhibit MAO and does not enhance the release of biogenic amines. 4. Studies on electrically stimulated brain slices suggest that nomifensine does not directly stimulate dopamine (DA) nor noradrenaline (NA) receptor sites. 5. 5-Hydroxytryptamine (5-HT) uptake is not inhibited at "therapeutic" concentrations of nomifensine. 6. Nomifensine differs from the tricyclic antidepressants by virtue of its effect on the dopaminergic system.