Which neurotransmitter is linked to eating and alertness, with too little linked to depression?

The correct choice is associated with norepinephrine, which plays a significant role in regulating mood, alertness, and appetite. Norepinephrine is involved in the body's stress response and typically helps to enhance alertness and focus. When levels of norepinephrine are low, individuals may experience decreased energy levels, which can contribute to symptoms of depression.

Additionally, norepinephrine helps to modulate hunger signals; insufficient amounts can lead to altered eating behaviors. This relationship emphasizes the balance required for both mental health and physical well-being. Understanding the function of norepinephrine provides insight into its importance in both alertness and mood regulation, linking it to the symptoms described in the question.

In contrast, dopamine primarily influences mood, reward, and pleasure. While its imbalance can also relate to mood disorders, it isn't directly tied to the regulation of appetite. Serotonin is well-known for its role in mood stabilization and is often linked to feelings of well-being, but it does not directly correlate to eating and alertness as closely as norepinephrine. Endorphins are involved more in pain relief and feelings of pleasure rather than directly influencing eating behaviors or alertness in this context.