National Certified Addiction Counselor, Level I (NCAC I) Practice Exam

How does PCP's mechanism of action function?

1. Inhibits serotonin production

2. Activates glutamate, an excitatory neurotransmitter

3. Blocks dopamine receptors

4. Increases GABA levels

The correct answer is: Activates glutamate, an excitatory neurotransmitter

PCP, or phencyclidine, operates primarily by interacting with the glutamatergic system. Specifically, it acts as an antagonist at the NMDA (N-methyl-D-aspartate) receptor, which is a subtype of glutamate receptor. This means that PCP inhibits the action of glutamate, an excitatory neurotransmitter, leading to various effects on the brain and behavior. By blocking these receptors, PCP disrupts normal neuronal communication associated with cognition, perception, and mood, resulting in symptoms such as dissociation, hallucinations, and altered states of consciousness. Understanding the role of glutamate in the central nervous system is crucial, as it is the main excitatory neurotransmitter and plays a significant part in learning and memory functions. Therefore, PCP's action not only affects sensory perception but also has implications for learning and memory processes. The other choices do not accurately reflect PCP's pharmacological profile, as the drug does not primarily inhibit serotonin production, block dopamine receptors in the conventional sense associated with antipsychotics, or increase GABA levels, which relate to inhibitory neurotransmission rather than the excitatory mechanisms that PCP affects.