What effect does Phenelzine have on neurotransmitter levels?

Phenelzine is a monoamine oxidase inhibitor (MAOI) that primarily functions by inhibiting the activity of the monoamine oxidase enzyme. This enzyme is responsible for the breakdown of neurotransmitters such as norepinephrine, serotonin, and dopamine in the brain. When phenelzine inhibits MAO, it leads to a reduced breakdown of these neurotransmitters, which effectively increases their levels in the synaptic cleft. This increase in norepinephrine is particularly relevant as it is associated with the therapeutic effects of phenelzine in the treatment of depression and anxiety disorders.

The correct answer highlights this important mechanism of action, emphasizing that by inhibiting the breakdown of norepinephrine, phenelzine enhances its availability and activity, contributing to improved mood and emotional regulation. This is a key concept in understanding how MAOIs work and their impact on neurotransmitter dynamics in the central nervous system.