Neurotransmitter definition and mood regulation pair:

• A. A chemical messenger in the brain; examples: gamma-aminobutyric acid and glutamate.
• B. A chemical messenger in the brain; examples: serotonin and norepinephrine.
• C. A chemical messenger in the brain; examples: serotonin and dopamine.
• D. A chemical messenger in the brain; examples: acetylcholine and melatonin.

Answer: (C)

Mood regulation hinges on brain chemicals that act as messengers, with serotonin and dopamine standing out as a classic duo. Serotonin helps stabilize mood and modulate anxiety and social behavior, contributing to a sense of well-being. Dopamine, meanwhile, shapes motivation, reward, and pleasure, and also influences mood states through its role in how we experience motivation and reward. When you pair these two, you capture two key pathways that commonly shape how we feel day to day: a serotonin-driven mood baseline and a dopamine-driven drive and affect.

Other pairs mix neurotransmitters that don’t align as directly with mood regulation. GABA and glutamate govern the balance of brain activity—inhibition and excitation—more about overall neural tone than mood itself. Acetylcholine and melatonin relate to attention/arousal and sleep-wake cycles, not mood per se. Serotonin with norepinephrine is also relevant to mood, but the combination with dopamine continues to illustrate the mood-related influence of both a mood-stabilizing transmitter and a reward/motivation signal.