What is the mechanism of action of cocaine?

The chosen answer highlights cocaine's primary pharmacological action, which involves blocking the reuptake of key neurotransmitters in the brain, specifically dopamine, serotonin, and norepinephrine. This inhibition leads to an accumulation of these neurotransmitters in the synaptic cleft, which enhances their signaling effects.

Focusing on dopamine, this blockade is significant because it is closely associated with the brain's reward and pleasure pathways, contributing to the euphoric effects commonly experienced with cocaine use. Similarly, the reuptake inhibition of serotonin and norepinephrine plays a role in its stimulant effects, as well as in various physiological responses such as increased heart rate and elevated mood.

The other options pertain to different mechanisms that are not characteristic of cocaine's action. For example, increasing GABA activity in the brain would suggest a depressant effect, while cocaine is a stimulant. Inhibiting serotonin synthesis or stimulating endorphin release does not accurately describe how cocaine operates within the central nervous system. These functions relate to other substances or mechanisms that do not apply to cocaine. Thus, the correct answer thoroughly captures the pharmacodynamics of cocaine as it relates to neurotransmitter interactions.