This form of MAO, found in dopamine neurons, acts on substances in the neuron other than dopamine. Inhibiting this form of MAO can increase levels of neurotransmitters such as serotonin, which seems to help people diagnosed with depression. Dopamine binds to its receptors quickly. This neurotransmitter is also quickly removed from its receptors as long as dopamine levels in the synapse are sufficiently high. However, drugs can affect dopamine levels.
Some drugs increase dopamine by preventing dopamine reuptake, leaving more dopamine in the synapse.
An example is the widely abused stimulant drug, cocaine. Another is methylphenidate, used therapeutically to treat childhood hyperkinesis and symptoms of schizophrenia. It's interesting that amphetamine and cocaine produce affect behavior and heart function in similar ways. Furthermore, both drugs increase the amount of dopamine in the synapse. However, cocaine achieves this action by preventing dopamine reuptake, while amphetamine helps to release more dopamine.