Final answer:
MAOIs, such as selegiline, block the enzyme monoamine oxidase, increasing the levels of neurotransmitters like dopamine, serotonin, and norepinephrine in the brain, which can alleviate symptoms of depression and anxiety. Their usage has declined due to their toxicity and severe interactions with certain foods and drugs.
Step-by-step explanation:
Monoamine Oxidase Inhibitors (MAOIs) like selegiline play a crucial role in treating various mental health conditions, especially when other antidepressants are not effective. The primary mechanism of action (MOA) of MAOIs is to inhibit the function of the enzyme monoamine oxidase. This enzyme is responsible for the breakdown of neurotransmitters such as dopamine, serotonin, and norepinephrine. By inhibiting monoamine oxidase, MAOIs prevent the deamination and subsequent degradation of these crucial neurotransmitters, leading to an increase in their levels in the synapses and improved transmission of neural signals.
The improvement in the availability of these neurotransmitters can potentially alleviate symptoms of depression, anxiety, and other neurological disorders. However, the use of MAOIs like selegiline is limited due to toxicity, potential lethal food & drug interactions, and the availability of other antidepressants with fewer side effects, such as Selective Serotonin Reuptake Inhibitors (SSRIs).