Final answer:
TCAs, SSRIs, and MAOIs increase neurotransmitter levels in the brain but differ in their action: TCAs inhibit the reuptake of norepinephrine and serotonin; SSRIs selectively block serotonin reuptake, and MAOIs prevent neurotransmitter degradation. SSRIs are better tolerated with less side effects compared to TCAs and MAOIs.
Step-by-step explanation:
The mechanisms of action of tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), and monoamine oxidase inhibitors (MAOIs) all serve to increase the levels of neurotransmitters in the central nervous system, but they do so through different processes. TCAs, such as imipramine and amitriptyline, primarily work by inhibiting the reuptake of norepinephrine and serotonin, which leads to higher concentrations of these neurotransmitters in the synaptic cleft. SSRIs, like Prozac (fluoxetine) and sertraline, selectively inhibit the reuptake of serotonin alone, thus having fewer anticholinergic side effects while also increasing serotonin levels.
On the other hand, MAOIs block the enzyme monoamine oxidase that degrades neurotransmitters such as dopamine, serotonin, and norepinephrine, resulting in their increased availability. However, while TCAs and SSRIs are well-tolerated, MAOIs require strict dietary restrictions to avoid hypertensive crises. Additionally, SSRIs have found use in treating obsessive-compulsive disorders, while TCAs can lead to unpleasant side effects like sleepiness and lightheadedness when administered to non-depressed individuals.