Final answer:
MAOIs work by inhibiting the monoamine oxidase enzyme, leading to increased levels of serotonin, norepinephrine, and dopamine in the synaptic cleft, which helps alleviate symptoms of depression.
Step-by-step explanation:
The mechanism of action of monoamine oxidase inhibitors (MAOIs) involves the inhibition of the monoamine oxidase enzyme, which is responsible for the breakdown of monoamines such as serotonin, norepinephrine, and dopamine. By inhibiting this enzyme, MAOIs increase the concentrations of these neurotransmitters in the synaptic cleft, which can improve mood and alleviate depression. This effect contrasts with other classes of antidepressants like selective serotonin reuptake inhibitors (SSRIs) which block the reuptake of serotonin into the presynaptic neuron, and drugs that influence the dopamine and norepinephrine systems, such as norepinephrine-dopamine reuptake inhibitors (NDRIs) and norepinephrine-serotonin reuptake inhibitors (NSRIs).