What therapeutic effect do MAOIs predominantly aim to enhance?

Monoamine oxidase inhibitors (MAOIs) primarily aim to enhance serotonin levels in the brain. They function by inhibiting the activity of the enzyme monoamine oxidase, which breaks down neurotransmitters such as serotonin, norepinephrine, and dopamine. By limiting this breakdown, MAOIs increase the availability and levels of these neurotransmitters in the synaptic cleft, particularly serotonin, which can help alleviate symptoms of depression and anxiety.

While chronically elevated levels of norepinephrine can also result from this treatment, the primary therapeutic effect attributed to MAOIs is their enhancement of serotonin. The other options focus on neurotransmitter activities that are not the primary targets of MAOIs, which is why they are not considered correct in this context.