Which neurotransmitter is known to be the most abundant inhibitory neurotransmitter?

GABA, or gamma-aminobutyric acid, is recognized as the most abundant inhibitory neurotransmitter in the central nervous system. It plays a crucial role in reducing neuronal excitability throughout the nervous system, which is essential for maintaining the balance between excitation and inhibition in brain activity. By binding to GABA receptors, it leads to the opening of ion channels that allow negatively charged ions to enter the neuron, making it less likely to fire an action potential. This inhibitory function is vital for various processes, including regulating mood, promoting relaxation, and preventing overactivity in neural circuits, which can lead to conditions like anxiety and seizures.

The other neurotransmitters listed serve different functions. Dopamine is primarily involved in reward, motivation, and motor control; serotonin contributes to mood regulation and is often associated with feelings of well-being; norepinephrine affects alertness and arousal. However, none of them primarily serve the role of the main inhibitory neurotransmitter as GABA does.