Which neurotransmitter is associated most closely with arousal reactions and moods?

Norepinephrine is the neurotransmitter most closely associated with arousal reactions and moods. It plays a crucial role in the body's response to stress or danger, commonly referred to as the fight-or-flight response. When norepinephrine is released, it increases alertness and arousal, heightening attention and focus. This neurotransmitter is also linked to the regulation of mood, and imbalances can lead to mood disorders, such as depression or anxiety.

In contrast, dopamine primarily influences reward and pleasure pathways, impacting motivation and feelings of enjoyment. Serotonin is essential for mood stabilization and emotional regulation, especially regarding feelings of well-being and happiness. GABA serves as the primary inhibitory neurotransmitter in the brain, playing a key role in reducing neuronal excitability, which can influence relaxation and anxiety reduction but is not primarily connected to mood and arousal in the same way norepinephrine is.