How do MAOIs affect neurotransmitter levels?

Monoamine oxidase inhibitors (MAOIs) work by inhibiting the activity of the monoamine oxidase enzyme, which is responsible for breaking down neurotransmitters such as serotonin, norepinephrine, and dopamine in the brain. By blocking this enzyme, MAOIs lead to an increase in the levels of these neurotransmitters.

Focusing on serotonin, the inhibition of the monoamine oxidase enzyme prevents the degradation of this neurotransmitter, resulting in higher concentrations in the synaptic cleft. This elevation can improve mood and alleviate symptoms of depression, which is why MAOIs are often prescribed for certain mood disorders.

Other options do not correctly describe the action of MAOIs. For instance, MAOIs do not decrease norepinephrine levels; instead, they can lead to increased norepinephrine due to their inhibition of the breakdown process. Similarly, the stabilization of dopamine levels is not the primary mechanism of action for MAOIs, as the specific increase in dopamine is more prominent with certain types of medications. GABA levels are not directly influenced by MAOIs, as these medications primarily affect the monoamines rather than the inhibitory neurotransmitter systems.