Tricyclic antidepressants primarily function by reducing the reuptake of which two neurotransmitters?

Tricyclic antidepressants (TCAs) are known for their mechanism of action, which primarily involves inhibiting the reuptake of norepinephrine and serotonin. This means that TCAs block the transporters responsible for the reabsorption of these neurotransmitters into the presynaptic neuron, leading to increased concentrations in the synaptic cleft. This elevation in norepinephrine and serotonin levels is believed to enhance mood and alleviate symptoms of depression.

While the other neurotransmitters mentioned in the choices—such as dopamine, acetylcholine, and epinephrine—are involved in various neurotransmission processes, they are not the primary targets of TCAs. Dopamine's role in mood regulation is more prominently the focus of other antidepressant classes, while acetylcholine is mainly associated with different neuronal functions and side effects related to TCAs, such as anticholinergic effects. Therefore, the specificity of TCAs in targeting serotonin and norepinephrine is what makes this choice the correct answer.