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

What neurotransmitter is inhibited by the action of adenosine in the brain?

1. Norepinephrine

2. Dopamine

3. Serotonin

4. Acetylcholine

The correct answer is: Dopamine

Adenosine is a neuromodulator in the brain that typically has an inhibitory effect on various neurotransmitter systems. When adenosine levels rise, especially during times of energy depletion or prolonged activity, it promotes sleepiness and relaxation. It does this by inhibiting the release of excitatory neurotransmitters, which includes dopamine. Dopamine is crucial for regulating mood, motivation, and reward pathways in the brain. The inhibition of dopamine release by adenosine helps to modulate these pathways, contributing to its sedative effects. Furthermore, the interaction between adenosine and dopamine is a critical aspect in the regulation of sleep-wake cycles and can have implications for conditions such as insomnia or attention deficit disorder. The other neurotransmitters listed, while they interact with adenosine in various ways, do not experience the same level of direct inhibitory action. Norepinephrine, serotonin, and acetylcholine may be influenced by the presence of adenosine, but the strongest and most notable inhibitory effect linked to adenosine's function is on dopamine. This makes the choice of dopamine the most accurate response to the question about which neurotransmitter is inhibited by adenosine in the brain.