Which neurotransmitter is primarily involved in the regulation of mood and has been implicated in the pathophysiology of depression?

GABA is the primary inhibitory neurotransmitter in the brain, primarily responsible for reducing neuronal excitability and promoting relaxation. While it plays a role in anxiety and stress responses, it is not directly implicated in mood regulation or the specific pathophysiology of depression like serotonin.

Glutamate is the main excitatory neurotransmitter and is involved in cognitive functions such as learning and memory. While it has been linked to various neurological conditions and can influence mood indirectly, it does not primarily regulate mood or serve as a direct factor in the pathophysiology of depression.

Dopamine is primarily associated with the brain's reward system, motivation, and pleasure. While it does play a role in mood regulation, its primary functions are more related to reward and motivation rather than the overall regulation of mood, making it less central to the pathophysiology of depression compared to serotonin.